Milan Zamazal's blog

I've been a satisfied eMusic customer for several years. Their interesting catalog providing unrestricted mp3 (even in the era of DRM madness) for reasonable subscription prices allowed me to find a lot of good music which I would have missed otherwise. About a month ago they notified me without further details that they no longer provide services in my area and that my subscription was cancelled. It was somewhat strange, but they were fair and refunded my whole year subscription.

Although I liked eMusic I don't regret it much. Nowadays there are other alternatives available, offering good music for reasonable prices and with standard selling model instead of the subscription service. So it's time to start spending money on music elsewhere. I'll start with picking my favorites from Indies Records and I'm also going to look at Magnatune. Any other tips for nice music mp3 shops?

I looked at a price list of PC CPUs after some time and wondered what AMD Phenom is. So I looked at the AMD website. To keep the story short I'll limit my experience to a single FAQ entry labeled "What is the AMD Phenom(TM) processor?", well representing overall information provided there.

The first part of the answer says: "AMD Phenom(TM) processors represent the next generation of AMD's award winning multi-core Direct Connect Architecture with AMD64 technology enabling greater memory throughput, lower latency and ultra-fast connections to system resources including graphics processors and accelerators." Well, so they say the new family of processors provides better performance than its predecessors. I wouldn't expect the opposite, so nothing new to me.

The next paragraph: "Featuring true quad-core technology, AMD Phenom(TM) processors are designed to deliver unprecedented megatasking performance and highly tuneable performance platforms to meet the demanding needs of technologically savvy enthusiasts." This paragraph is interesting because it contains the only single bit of information of the whole FAQ entry answer, i.e. that these processor are quad-core processors. But I could read this already in the price list. As for "unprecedented megatasking performance" and "highly tuneable performance platforms" I couldn't find anything indicating that it describes any real features so I suspect they are just marketing idle talks.

And finally: "AMD Phenom(TM) processors are designed for phenomenal performance and optimum energy efficiency for a growing list of demanding applications, including digital content creation, high-definition video editing, multi-threaded gaming and creative design. AMD Phenom(TM) processors are targeted toward mainstream users who crave more performance and productivity." I see, these processors are designed so that one can work with a computer. What a surprise!

So I still don't know what the Phenom thing is about. But I know now that either AMD are idiots or they have nothing great to say about this family of processors and they try to hide this fact in meaningless blurbs. In both cases I'd hesitate to buy AMD processors.

I decided to buy some chess books for the first time after many years. I'm going to start playing chess again, after several years long break. I think it might be a good step towards my mental recovery. I've been being busy with many dull activities last years and I haven't got much opportunity to employ analytical and logical thinking. Chess is great as it requires (except for its entertainment forms such as blitz) deep and careful thinking. Only then one can be rewarded with pleasant results while superficial approach may get punished very quickly, especially when playing against a computer. This is in big contrast to our common social environment that directs us to operate quickly, unreliably, in stupid ways and without understanding anything.

It's much easier to buy chess books now than it used to be the last time I was deeply interested in chess. Thanks to Internet shopping the choice of both new and used books is great and many interesting books became easily accessible. I bought the books from chessbookshop.com operated by a retired GM Karel Mokrý. I must say I was very satisfied with it and I can recommended that shop to chess lovers.

I've been using two monitors with two graphics cards on my computer for long time. I've got another spare old CRT monitor so why not to utilize it? I connected it to a free VGA port on one of the cards and started experiments.

Compared to the two independent graphics cards setup, using two monitors connected to a single card handling a single desktop was relatively easy. By default the monitors show the same screen. I tried to setup Xinerama but these attempts have always finished with X server segmentation faults. After some more searching I've found that the proper tool to use, other than Xinerama, is XRandR. I just had to upgrade the xrandr utility to a newer version. Then it was easy, using xrandr one can play with dual monitor setups on the fly, without needing to restart the X server (which is equal to reboot on my dual card machine). And StumpWM works great with XRandR, I had just to figure out that the second monitor screen is nothing else than another frame.

The only problem is that the whole XRandR setup is limited to the total possible graphics card resolution, 1920x1200 in my case. So the second monitor is limited to 640x480 resolution in my setup. But it's still well usable for tasks like watching TV while doing something else.

I've been a user of Microsoft products for some time now. No, I didn't install their operating system on my workstation of course. But I started to use their Natural Ergonomic Desktop 7000 wireless keyboard + mouse set.

When looking for an ergonomic wireless keyboard several months ago I've found that the Natural 7000 set is the only choice. Except for Microsoft, only Logitech offered split wireless keyboards, but they didn't manage to understand where the backslash key belongs to so it was no option for me.

Surprisingly this new Microsoft keyboard is based on the standard keyboard layout, with addition of some more or less useful keys. It fits into my hands very well and typing on it is more comfortable than on my old Chicony ergonomic keyboard. Its adjustable tilt looks like a good idea to me, I like it. It was just necessary to get use to the keyboard as it's somewhat different to my previous keyboard in its shape. I also had to get rid of my bad typing habits to use the keyboard well. I can't judge on real usefulness of the extra keys because they don't work with the latest Linux VServer kernel and I have to wait until VServer gets updated for the last Linux changes. My only complaint about the keys so far is that the multimedia keys look very cheaply built and feel like they could fall apart any time. But Microsoft offers three year warranty for the set so we'll see.

The mouse feels very well too. I think the side holding approach is a very good idea, it became relief for my hand after some time of its use. The mouse is nice to handle, it's just too sensitive for my taste (any way to get it change in X?). Some people complain the mouse is too heavy but for me it's completely fine. The side buttons are easy to reach for me (unlike for most people who reviewed the mouse on internet). There is one problem with the mouse: The left and right scroll wheel movement and especially clicking the scroll wheel (the middle button) are very though. I often have to press the middle button more than once before it actually clicks. I don't know whether this is a feature or a problem of my particular mouse.

It's necessary to note that my hands and fingers are longer than average and that people with smaller hands may feel both the keyboard and mouse uncomfortable.

I can't say much about the operating range of the keyboard and mouse as I use them very near to the receiver. I tried to type something and handle the mouse at several places about 5 meters away from the receiver including one thick wall in between and it seemed to work well as long as there was no special obstacles in the way, as a computer case or my body.

As for the power source I put some old NiMH accumulators to both the keyboard and mouse. They last for about 1-2 months in the keyboard and for about twice as long in the mouse (note I use a keyboard much more than a mouse). Although both the devices are equipped with low battery warning lights, they appeared to be useless. For the first time when the accumulaters got exhausted the keyboard suddenly stopped work in the middle of typing, the same happened later to the mouse. The next time the keyboard light just blinked shortly three times and the keyboard stopped work immediately after that. Perhaps it would work better with alkaline batteries, I don't know.

Overall I'm pretty satisfied with the set despite its minor annoyances. It's really ergonomic and well usable and this is what matters for me.

Sometimes the possible consequences of connecting old flashes to modern electronic cameras (both digital and film) through hot shoe are discussed. The problem is high voltage (up to at least 300 V) of those flash units on their contacts, exceeding the standard limit of 12 V. I've never heard about a destroyed camera from direct user experience, but people are warned not to try such things.

What's my own experience? An old simple hot shoe flash with voltage about 90 V on its contacts usually worked with my Pentax MZ-M camera, but I sometimes experienced delayed mirror return (for about half a second) after taking a snapshot. I was more cautious with my other body, Pentax Z-1, reported to be sensitive to high voltages. I once attached another flash unit, 40 V, to it. Two snapshots went fine, but on the third one it actually happened what the rumors had warned about: the camera got completely frozen and I had to remove the battery from it to get it alive again. However no other damage has happened.

I no longer risk damaging my cameras by using old flash units. I bought a used Pentax flash unit for €15, with safe voltage. It is only a bit stronger than common built-in flashes, it doesn't have any TTL etc., but it works, it's safe, cheap, small, light, inconspicuous and communicates with the Pentax cameras. It's enough for my occasional flash use.

This is my warning to other photo amateurs: Although no permanent damage has happened to my cameras, I can confirm that using old flashes with voltage higher than 12 V on their contacts may cause at least temporary malfunctions. And it's not true that Pentax cameras are safe up to 600 V.

Some time ago I've finally managed to get my Epson R220 printer somewhat calibrated. Standard Gutenprint drivers suffer from strong green cast on this printer and I wasn't successful to get it corrected directly in Gutenprint. Trying to play with the driver color settings has led me only to other problems, replacing one kind of color cast with a different one. Much better than standard settings but still not always usable. So the only way to print photos on my printer was performing printer color calibration. How did I do it?

First I installed Argyll color management system. It's not included in Debian (I guess not many people perform color calibration regularly and they are scared of irregularly maintained software with lots of possible problems) but it can be compiled and run easily. It's just not easy to use it. But it contains complete documentation, so with enough time, patience, ink, and paper it's possible to get the desired results. I didn't have enough time during last year so it took me more than one year, but it seems to work now.

The first step was to calibrate my desktop scanner. This was necessary to scan the printed samples for calibration processing. I ordered a scanner color calibration target from Wolf Faust and followed instructions from Argyll documentation. This step was relatively easy and I got my scanner calibrated soon.

The next step was significantly harder. When I tried to generate color patches for my 6-color ink printer Argyll created just greyscale patches. I didn't understand it, although the Gutenprint driver apparently uses inks other than black even on greyscale images (as long as color printing is enabled), I decided not to go this way. So I generated and used patches for an RGB printer. Yes, it's probably completely wrong from the point of serious calibration, but it basically works. First I tried to generate the patches for the target 10x15 media but the number of the patches on this area was too small and the calibration results were bad. I didn't have a larger piece of paper of this kind so I used a different kind of paper in A4 size. Professionals would probably fall faint reading this but I wasn't willing to spend another €15 for paper in order to print our family photos perfectly. Then I had to scan the printed results and to process them with Argyll. The process was smooth once I had managed to use proper commands with proper arguments and proper use of the srgb.icm file (taken from digiKam).

The final step was setting the color profile in PhotoPrint. This was easy and worked very well.

Of course my calibration process had several serious flaws: I used a desktop scanner instead of a proper measurement tool, I generated color patches for another kind of printer and I used different kinds of paper for calibration and printing. But the results are still better than any of my previous attempts of manual adjustments. They are not perfect, but my old digital camera is not either, not mentioning my uncalibrated monitor. And I'm glad that faces on the printed photos are no longer green nor violet. This makes my family satisfied enough :-), so this poor man color calibration fulfilled its purpose.

I've recently read an article from The Economist newspaper (reprinted in a Czech newspaper) about global positive changes of the world. Let's look at some arguments presented in the beginning of the article.

They say that number of people with income of one dollar per day or less has strongly decreased in China during the last 25 years. No mention whether the "one dollar per day" is just a term for a standard comparable unit of what you can buy for your basic living or whether it should be taken as actual monetary income and thus it doesn't say anything because what you could buy for one dollar in (different areas of) China 25 years ago and what you can buy for it now is likely to be very different.

Another argument was that the number of children dying before the age of 5 has decreased by one quarter worldwide since 1990. As I don't have any idea how many small children survived, I don't know whether the decrease was achieved by improvement of health care, living conditions, etc. or perhaps just by reduced birth rate. Neither I understand why global changes are once demonstrated by data from China and next time by worldwide data.

I didn't bother to read the rest of the article. Improper use of relative and absolute numbers and careless mixing of different sources is either ignorance or manipulation. The article was an excellent demonstration of the saying that with enough statistical data you can prove anything. This doesn't necessarily mean the conclusions are wrong, they are just based on void inputs; whatever they would say and conclude could be "proven" using such methods.

The shame is such a stupid article could be printed in a media which are probably willing to be taken seriously. It reminds us that we should be careful about all inputs and conclusions presented in newspapers.

About once a year I manage to attend a live music show. This year I've chosen Autopilote (Fajt, Smeykal, Yumiko, Holý, Václavek). I watched them in Noc s Andělem on TV a few weeks ago and I liked the music, thinking it might be nice to listen to it live. This opportunity came yesterday and the concert was great, incomparable to what I could previously hear on TV. For me the music is catching and original, I've never heard something like this, it just evokes (not surprisingly) some Brno roots. Recommended.

We have moved from qmail to Exim recently on our company mail server. It is a big relief. The mail server can handle the high amount of incoming junk mail now, it is reasonably manageable and provides readable logs.

It was late transfer. It is not easy to move a mail server to a completely different software and it happened only after more significant qmail problems than just a weird licensing conditions arose. But the important question is: What are the lessons?

Many years ago I was enthusiastic about qmail myself. In comparison to its common alternatives of the time, Sendmail and Smail, qmail was innovative and elegant. I only became a bit reserved about it when Debian Free Software Guidelines explicitly excluded qmail from Debian (there is a special item in the document inspired directly by qmail licensing problems) and djb (the qmail author) became well known for his poor communication style. The time has proved these issues were important and I stopped using qmail on my machines. Now, many years later when qmail is semi-dead and we can look backwards, I can identify three major lessons from the qmail rise and fall.

The first lesson: Beware of non-free software of any kind. Although qmail original license didn't prevent modifications and their distribution, it was restrictive enough to prevent unlimited spread of the software and it put obstacles to contributors and users. In the final result qmail was unable to adapt to new conditions appropriately, namely it is incapable to handle junk mail. Although djb put qmail to public domain recently, it was too late, as with many other pieces of dying non-free software (but it may be still better than to let the software die completely).

The second lesson: Software can't be completely separated from its author. If he is blinded by his pride, numerous problems can appear. For instance the semi-restrictive qmail licensing conditions served no good, they were designed just to satisfy author's ego. Completely ignoring compatibility with other similar software makes adoption of new ideas more difficult. Telling other people they are idiots (either explicitly or implicitly) discourages contributors, doesn't educate the users and builds a wall around the author preventing him from considering other opinions and correcting his wrong decisions. In the final result the software can't utilize its full possibilities and it degrades.

The third lesson: Security is a more complex concept than just avoiding privilege escalation and buffer overflows. Empty security advisory track may look nice but what is it good for when the mail server gets permanently irresponsive under junk mail floods, distributes junk mail itself through bounces and one has to apply third party patches not covered by the security warranty? In such a case the security statement is mostly just a blurb without connection to reality.

Why did I select Exim as the new MTA on our company server? Two mainstream good MTAs today are Exim and Postfix, they are mostly comparable and both the Exim and Postfix communities talk with respect about each other. So as a matter of personal preference I selected Exim which was already known to me.

Amazon is going to sell their new e-book reader. Sure, I wouldn't buy a proprietary device that serves as a purchase tool for a particular seller. But a more interesting thing is that they advertise access to Wikipedia several times in their blurbs.

I'm curious whether Amazon is going to support Wikipedia, e.g. by donating some reasonable amount of money for each e-book reader they sell, or whether they are just parasites who misuse a free project financed by someone else. I already boycott Amazon because of their dirty business practices (using software and business method patents to beat their competitors). But if they use Wikipedia to market their products without supporting the project (and I guess they would proudly tell us if they supported it) then it's another reason to avoid buying anything from them. So does anybody know something about any Amazon and Wikipedia relationship?

BTW, one positive result of this issue is that it reminded me I should donate to Wikimedia Foundation during its current fundraising campaign.

Film scanners are often claimed to be superior to flatbed scanners when scanning 35 mm films. The harder thing is to find actual facts supporting such claims. Actually it's possible to find samples suggesting there is no significant difference between the scanners. And even Minolta was able to find the only relevant argument for film scanner superiority on their site: better optics.

The fact is that I was sometimes dissatisfied with a cheap flatbed Epson Perfection 2480 Photo scanner. I can compare its outputs with a dedicated film scanner (Nikon LS-40 / Coolscan IV) now. Indeed, there are significant differences in the results.

As for image quality I could observe the following:

• Every film defect (scratches, dust, garbage) is clearly visible in Nikon scans. Without digital ICE the Nikon scanner would be almost unusable. Epson is much better in this area and thus it's the only option for scanning my old b&w negatives.
• The true resolution of the Nikon scanner is clearly superior to the Epson, despite their nominal resolutions are almost the same (2900 versus 2400 ppi).
• Nikon is much less prone to grain aliasing.
• Nikon output can be used without further processing, sometimes small level of USM improves the image. Epson output is very soft and typically requires strong USM followed by noise reduction and additional USM to get well looking results (but still somewhat inferior to unprocessed Nikon output).
• Epson suffers from irregular annoying stripes in monotone image areas, in the direction of scanning. This is one of the worst and completely unavoidable problems of the scanner.
• Nikon has shallow depth of field and the scan is often sharp in the center (the default focus point) and unsharp near the film field borders. Special care is needed to reduce the effect. Epson is much better in this area.
• Epson poor film holders make the scans prone to terrible reddish artifacts near the both ends of film stripes.
• There seems to be no relevant difference in the dynamic range capabilities of the scanners when scanning negatives.

To summarize: While one can often receive similar results from the scanners, there are situations where only the film scanner is able to produce good results. IMHO it's really worth to consider investment into a dedicated film scanner instead of a cheap flatbed. On the other hand the flatbed scanner may be superior when scanning imperfect films when digital ICE can't be used.

Besides the image quality convenience may also matter:

• Epson is much faster, I'd say I can scan a roll of film with it twice as faster than with Nikon.
• Nikon can load film stripes itself (some flatbeds can do that too). On the other hand it's sometimes difficult to force it to move the film field to the desirable position so that it could be scanned whole, without cutting out any part of the film field area. I don't know whether this is a problem of the scanner or of something else (driver? user?), but it's annoying.

And finally, which low-end film scanner to buy? The cheap film scanners such as Plustek or Reflecta don't seem to provide quality comparable to standard middle-range film scanners. A used Nikon LS-40 / Coolscan IV seems to offer very nice quality/price ratio for an advanced amateur. Older Nikons are SCSI devices, i.e. quite inconvenient to use with contemporary personal computers. Nikon LS-50 / Coolscan V is one of the rare middle-range film scanner models still in production. Minolta Dual scanners are cheap, but they don't have Digital ICE (which makes their use very inconvenient), they seem to be more prone to grain aliasing and they are infamous for banding problems. If I understand the technology right, Nikon scanners are superior in their LED light source: It's very reliable and there is no color interpolation (each pixel is scanned in all the color channels separately). Minolta Elite 5400 scanners look very nice but they are more expensive and the II model is known to be prone to defects. I don't care about Canon scanners as they are completely unsupported in SANE. As for SANE support, AFAIK only Nikon LS-30 and LS-40 and Minolta Dual II and III are reported to be fully supported.

HTH, although it's all mostly a personal opinion of course.

Mike Oldfield's Incantations is a nice piece of music to listen to during hot summer days. Like many Oldfield works, it may not sound that great on the first (maybe also second or third) listening ("huh, who would like to listen to all the long repetitions?") but then, as aptly expressed by someone on the net, it falls on you. I've listened to this last of the initial great Oldfield's works many times through the last years and it has never bored me. So if you can find opportunity to spend an hour and a quarter at a calm place without being disrupted, you can try to enjoy the repetitive patterns of Incantations.

Well, I switch the revision control system I use for the third time during last years.

When I decided to try something else than CVS, I started with GNU arch. This was a good choice as GNU arch made a good basis of modern free software revision control systems. Unfortunately problems in GNU arch development and its split into unconvincing forks and replacements forced me to look elsewhere.

There were several reasonable choices among distributed revision control systems: darcs, Mercurial and git. I switched to darcs as it looked simple, user friendly and was popular among Lisp programmers. Indeed, as long as darcs is used for a single line development (as is typical with Lisp projects because they usually don't require much development power) it works very well. I was very satisfied with it until I have been hit by the infamous darcs performance problem. This is a fatal drawback preventing use of the revision control system at all in certain situations. So I had to switch to another system once again.

The remaining choices were Mercurial and git. I decided to go git as it looked more reliable to me (something used for Linux kernel development is unlikely to be seriously buggy or suffering from performance problems, isn't it) and provided "native" tools for cooperation with CVS (this is important to me as I usually work on projects with upstream CVS repositories).

I've been using git for several months now and I'm satisfied with it. From the user's point of view it's somewhat ugly and unfriendly, but one can live with it using a few external tools such as Emacs and qgit. More important is that the underlying concepts look right. Also the git CVS cooperation tools work better than tailor that the other systems use. I think git future is promising, git seems to be well founded, with stable development and growing user base (I know I'm not the only one migrating through the systems as described above and being now a git user). Perhaps git is the future leading free revision control system and I won't have to migrate again in the next years.

Sharp Zaurus SL-C1000 is shipped with its own Linux operating system based on Qtopia. The system is not bad, it is stable and although it requires some updates to become really usable, it provides nice PDA environment covering many areas of use. But it suffers of some problems: it's incompatible (as it uses Qtopia instead of X), contains a lot of proprietary applications and the available development environment is obsolete. Simply said it's difficult and annoying to port applications to the system.

So I decided to replace the Sharp operating system with pdaXrom, which is a free X-based operating system for (Sharp) PDAs. They say the operating system replacement should be safe as the Zaurus low-level system service menu is placed in ROM and can't be erased. First I tried to install the latest pdaXrom release, i.e. 1.1.0r121. This was a mistake as the device ended up seemingly completely dead after reboot. It took me a lot of googling and experiments to get it recovered and to install pdaXrom 1.1.0beta3 which seems to work fine so far.

The first advice: Don't install the latest 1.1.0r121 release, install 1.1.0beta3 instead (until some new stable version is released) which has reputation of being relatively stable.

The second advice: If you end up with a "dead" C1000, you can recover it as described on the TRIsoft site. But there is an important missing detail there: You need to press Fn+D+M to start the service menu, not only D+M.

One of the main advantages of digital photography over film is that all the process is in your hands. With film at least its development is usually left to a laboratory. And this is a problem, I've experienced a lot of troubles with it: scratches, sticked garbage, fingerprints, even exchanging my roll of film with one of another customer. In the better case I can partially repair some of the damages spending a lot of time on retouching, in the worse case the shot is lost. I'm not a photographer who takes a lot of pictures and then chooses a few pictures from a roll of film, I usually spend significant amount of time on taking each shot and don't shoot the same picture twice. So if they damage my shot, it's completely lost.

I don't want to risk those problems anymore. As I don't know how to find a good laboratory in Brno, I have two alternatives. Either sending my films for development to PHOTO life's CREATIVE LAB (they claim they handle everything in the process very carefully) or developing the films myself. With my low-volume production I'll probably try the first choice. It means about 3 € extra cost for postage, but it still looks like the cheapest way to get the thing done right.

BTW the laboratories in Brno that show complete incompetence are Fosh foto and Fotex (at Kobližná).

My first X Window workstation ran pretty will with just 8 MB RAM. Nowadays even 2 GB RAM (i.e. 256 times as much) is not enough for personal use. My workstation runs 24/7, so I sometimes check what consumes all the memory capacity. I can usually identify the following processes being the cause:

• Firefox 2. When I upgraded to it from 1.5 I was happy my web browser didn't crash anymore. But there's another problem with it: it can easily consume up to several hundreds MB of RAM, so it has to be restarted from time to time. This is the most embarrassing case, the flagship free web browser is a memory hog even after so long time of its development .
• Vlc serving my DVB-T card. The vlc server gets sometimes completely crazy and starts consuming a lot of CPU time and memory. This is the most dangerous case because it can put the computer out of normal operation if the vlc process is not restricted.
• Some Xfce applets. There are clearly memory leaks in them. Well, unlike GNOME panel and applets, Xfce applets work as expected otherwise.
• Amarok audio player. I really don't understand why an audio player needs more than 100 MB of memory.

I've recently listened to (), the untitled album, by Sigur Rós. It's an interesting piece of music. I can't say much about it, try listening to it yourself.

I've recently looked for free software related to civil engineering. To my surprise there is probably not any. There are several projects that could potentially be used in civil engineering but none of them is directly usable for that purpose. For example 2D drawing tools may be good enough for electrical or mechanical engineering but do not provide means required for drawing construction plans.

Perhaps most people working in the area of civil engineering have some access to professional tools and that is all they need. If your needs are different and you miss civil engineering free software, let me know.

I don't understand why webshops put so much effort into making buying goods in them more difficult. My favorite hardware shop used to be ALFA COMPUTER, one of the reasons I liked them being their simple and well arranged web pages. That's gone now. They've recently introduced new web pages. The worst thing in them is heavy use of tables and pixel based dimensions. This results in a garbled screen unless a user uses particular screen resolution or is willing to destroy his eyes by reading 7-10 pixel characters on a 1280x1024 monitor.

I complained to the webmaster and he kindly explained me that using pixel based sizes is necessary to get the look "right" and that I can use a magnifier web browser function if I can't read the small font. As most users like the new pages, I gave up. Although I usually buy hardware in real shops, I actually choose it in the corresponding webshops first. As this is no longer easily possible for me with ALFA COMPUTER, they've lost a customer.

Looking over other hardware web shops here I can see such a stupid approach to making web pages is no way unique. And this is not the first time I switched to another hardware seller because of broken web pages. It must be some crowd effect that motivates webshops to make slow, unreadable and confused web pages that take customers away. BTW, any good hardware seller recommended?

Scanning software should deliver maximum information in the best possible form. It's not necessary to avoid further processing, but it's important to keep it possible and to perform processing steps that can be made automatically without losing important information. Choosing right scanning tools is important as mistakes in this process may result in the necessity of repeated scanning and processing. How is it with scanning negative films on Epson Perfection 2480 Photo?

The original Epson scanning software on Windows usually produces good results, but one must be careful to actually receive them. Obvious selections are setting colors to 48-bit (or 16-bit in case of bw negatives) and resolution to 2400. "Improvement" options should be all disabled, especially dust removal that in my experience actually doesn't remove any dust but removes many details instead (this is a pure software algorithm, the hardware doesn't support any dust removal features). Note that unsharp masking has to be disabled for each scanned film field individually. When you forget it, you receive bad results when you try to apply unsharp masking later yourself. Usually the software produces good colors (better than I'm able to get from the negative by other means now) although manual corrections are often necessary during post-processing, as is common with color negatives. It happened to me once with a few strongly overexposed film fields that the software has chosen very aggressive color clipping and I had to adjust histogram settings and rescan the given fields again. The Epson software requires a lot of mouse clicks (on average more than 2 for each scanned field) and suffers from memory leaks, requiring occasional restarts.

On Linux the scanning process is more challenging. The SANE driver supports all the crucial hardware features and scanning half a film strip requires just a single scanner button press (when you use scanbuttond) and no mouse clicks. But here is a small 1:1 sample of what you receive (contrast is much increased in all the examples to demonstrate the problems more clearly):

Note two things:

1. The very ugly stripe about one quarter from the left in the image. This is not a scratch on the film, this is a systematic defect.
2. The regular pattern of vertical one pixel wide darker and brighter stripes around edges of dark areas.

As for the special ugly stripe, it helps turning quality settings off (i.e. removing the '--high-quality=yes --quality-cal=yes' scanimage command line options). I guess their meaning is reversed in the driver by mistake. So here is new result:

The extra stripe is gone, but the regular stripe pattern is still there. I've no idea why it's there but I've seen something similar in the samples from other scanners on the net so it's likely to be some common hardware feature. FWIW, scanning direction is vertical here. No such apparent stripes are present when the same image is scanned with the Epson software on Windows:

So I tried to get rid of the stripes by averaging each two neighboring stripes into a new "neutral" stripe. This operation shouldn't lower resolution of the image, it may just soften it (and the actual scanner resolution doesn't correspond to the scanned image size anyway). So it should be safe. Here is what I received after applying the following imagemagick commands:

convert -crop 199x158+0+0 image.png crop1.png
convert -crop 199x158+1+0 image.png crop2.png
composite -blend 50% crop1.png crop2.png result.png

I think the result is pretty close (except for contrast adjustments) to what Epson software produces, so it's probably the way to go.

All the things presented here may look clear and simple. But it took me long time coming from the first naive scanning attempts to discovering why the scanned images don't look well and finally finding out all what's described above. Now I know supporting a piece of hardware doesn't mean just providing raw low-level drivers to the hardware. The hardware specific post-processing part is also very important and the user may receive poor results if this part is missing.

I've recently installed Debian etch distribution on an external USB hard drive. I was positively surprised how smooth the installation process was and how well the resulting system worked. Especially Czech environment was complete and well set up for the Czech speaking user without any need of further adjustments. The release managers and the debian-installer team do clearly good work and Debian 4.0 freeze may be short.

The only problem was how to boot from the USB drive. Initially it appeared to be easy as the computer offered USB booting in BIOS. But that didn't work, perhaps the BIOS was buggy. So I decided to make a bootable CD for the system.

For the record, here is the process of making a bootable CD for an etch system on an external USB drive. Some steps may be redundant, I don't know, but the final CD worked and this is what matters.

• Connect the USB drive to a similar computer, mount it and chroot into it.
• Install the 'initramfs-tools' package.
• Add the following module names to '/etc/initramfs-tools/modules': 'usb-ehci', 'usb-ohci', 'usb-uhci', 'scsi-mod', 'sd-mod', 'usb-storage'.
• Run 'update-initramfs'.
• You can leave the chrooted environment now.
• Install 'syslinux' and read its documentation.
• Create a syslinux working directory as described in the syslinux documentation. Name the kernel image file 'linux' unless you want to change the defaults. Don't forget to put the following option (the only one required) into 'isolinux.cfg': 'APPEND initrd=initrd.img root=/dev/sda1' (change the names of the initrd file and root partition accordingly).
• Make the ISO image, burn it onto CD and boot it.

I've switched almost completely from using a compact digital camera to using a film camera this year. I scan my 35 mm negatives with a low-end flatbed scanner, namely Epson Perfection 2480 Photo. It is possible to obtain reasonable results using that cheap device, but it's not easy. I've been learning a lot during the process and I'd like to share my experience in the posts here, perhaps it helps someone.

First, what can one expect?

As for the scanner dynamic range, I think it's sufficient for scanning amateur print films, I haven't observed any problems in this area.

As for the scanner resolution, Epson claims something about 2400 dpi regarding that scanner. I'd say such numbers are pure marketing crap nowadays for two reasons: 1. it's not defined what the number means; 2. whatever it's supposed to mean it has probably little to do with reality, i.e. the real scanner resolution. According to internet rumours and my own observations, such as down and upsampling scanned pictures and comparing scans with prints, I estimate the actual scanner resolution performance is very roughly around 1000 ppi. That means the spatial information the scanner is able to capture from a standard 35 mm film field is present in a picture of a minimum size of about 1500x1000 pixels.

So in theory the scanner should be sufficient for both my primary target medium, a 1280x1024 computer screen, and my secondary media, occasional prints not larger than A4. In practice it's not that easy but more on this next time.

Wouldn't it be worth to buy a better scanner? I don't have any experience with current more expensive scanners, but from what I've read and seen on the net, I think they provide somewhat better results with significantly higher comfort for much more money. Higher Epson flatbed scanners such as 4x90 or V7x0 produce better results and offer hardware features for dust removal, but increase in the device cost is significantly higher than increase in the resulting scan quality. Low-end "4000 dpi" dedicated film scanners give even better results for even more money. Drum scanners produce much better scans than Epson 2480 for 100 times more money. Basically it's your choice whether you invest much more money into better scanning hardware producing good results or much more time into scanning process using a cheap scanner producing acceptable results. Or whether you buy a good digital camera equipment and get rid of scanning entirely.

About a week ago, I've upgraded CUPS from 1.1 to 1.2 on my print server. I know one should never touch a working CUPS installation, but as Debian 4.0 is based on CUPS 1.2 I'd have to make the upgrade sooner or later anyway.

Of course, after the upgrade my printing stopped working as usually. As this was my second CUPS 1.1 to 1.2 upgrade attempt I already knew about some problems of the upgrade process and could get run at least the CUPS HTTP and IPP interfaces. But the printers worked in weird ways such as printing a single page in several pieces put on separate sheets or stopping to work after finishing a printing job.

To keep the story short, after a week of various efforts I ended up with complete removal of printing software on the server and its reinstallation. Then the CUPS HTTP configuration interfaces started to offer right configuration items and after a few attempts I could get my printing run properly.

I can only hope that after the upcoming Debian 4.0 release Debian slows down its release cycle again, so that I won't have to suffer all the software upgrade headaches each one or two years... In the meantime, let we software developers think more about impact of the changes we make to our great software.

Some Czech spammers are completely impudent and ignoring Czech law forbidding spamming activities. Europe should be civilized enough to be able to prevent such behavior here.

I've received another piece of spam from Hotel u Lípy today. Enough is enough, so I started looking for possibilities to retaliate, resulting in posting a grievance against them to Úřad pro ochranu osobních údajů (The Office for Personal Data Protection) that is responsible for dealing with such cases. They have an electronic form allowing Czech citizens to report abuse of the anti-spam law. Similar means should be available in other civilized countries as well.

I don't think it's much useful to report random spammers who may not be well aware about what they are doing. Just complaining to them and their ISPs may be a better way to deal with it. But we shouldn't hesitate to officially fight regular spammers ignoring private complaints. Although the office apparently lacks man power to deal with the reports quickly, they should be able to intervene some way against the spammers in the final result.

With the increasing complexity of modern user interfaces the number of annoying bugs grows. What is worse, number of long standing unfixed annoying bugs grows. The overall number of bugs grows and I'm able to do something only with a small part of them. Complex user interfaces have been being released without coming through a serious testing process (a typical example is GNOME).

One way how to handle this situation is to move from the complex user interfaces that don't work to simpler ones that do. I've recently switched from Sawfish and GNOME panel to Ratpoison and XFCE panel and I've been happy with the change so far. Ratpoison is, together with Stumpwm and Ion, a very simple window manager -- no window buttons, no borders, no workspaces, no systray, no customization dialogs, no mouse support. Instead you receive a window manager that works, can be easily and completely operated from a keyboard, utilizes maximum of your screen space and is well customizable. I was surprised how little of the complex functionality of other window managers I actually need. Ratpoison seems to offer all I need and to be more comfortable for me than classic window managers.

At the same time I switched from Firefox to Conkeror. The primary reason was that I got annoyed by being unable to reasonably operate Firefox from keyboard. Conkeror is similar to the window managers mentioned above (no wonder -- Ratpoison, Stumpwm and Conkeror were written by the same author). There are no toolbars, menus and other decorations, it can be operated from keyboard and it uses Emacs concepts (interactive commands invoked by M-x, buffers, mode line, minibuffer, echo area). Unlike Ratpoison, Conkeror has not been feature complete yet but it's possible to invoke the standard Firefox interface from it in case you need it. Additionally Conkeror is just another user interface to the web browser and as such it can't fix Firefox fatal bugs (such as crashes or freezes on certain pages). Anyway, I like it and I don't miss the standard Firefox interface often.

Well, here is a screenshot of my current desktop, do you like it? :-)

I've successfully finished my first year of distant study of civil engineering. Some fun, some hard work, as the distant study is mostly based on working out a lot of exercises. You can either actually make the exercises or you can copy them (which is formally disallowed of course). IMO the first way, although sometimes very time consuming, is better than learning the subjects by repeating exams and it is definitely much more effective measured by the actually gathered knowledge.

It proved to be manageable, but I can't recommend combining a regular job, building your new house by your own hands, extending your family, studying a school, etc. It's somewhat demanding :-). I hope I'll be able to manage things better in the next years.

When I scanned photos from the Fuji Superia 400 film I was very unhappy with grainy shadows. The grain seems to be really worse there than in brighter areas even when considering the effect of higher noise visibility in dark areas. I couldn't get rid of it even when I tried to significantly overexpose. By chance I found explanation of the problem in an old issue of the Czech PHOTO life magazine.

Actual sensitivity of negative amateur Fuji films (and this is likely to apply to other vendors' films as well) is very different from what one could assume looking at the declared ISO number. First, it is actually significantly higher than declared, protecting you from underexposition. Second, maximum sensitivity (i.e. the ability to capture minimum light without underexposition) is about the same regardless of the declared sensitivity, the difference between Fuji Superia 100 and 400 is reported to be only about 0,5 EV. When you expose Fuji Superia 100 at ISO 50, you can go up to 4 EV from the middle towards darkness before the material gets underexposed, while when you expose Fuji Superia 400 as ISO 200, you've got only about 2,5 EV.

This explains what I observe -- even when overexposing the ISO 400 film twice, there is a big risk of underexposed shadows, resulting in overgrown grain (note that according to Fujifilm specifications standard grain size should be about the same in properly exposed Superia 100 and 400). Indeed, scanning my latest Fuji Superia 100 film seems to confirm the facts. When I compare results from an ISO 400 film exposed as ISO 200 and from an ISO 100 film exposed as ISO 70, there is not much difference in the look of the grain in the highlights. But the grain is much worse in shadows of the ISO 400 film, while in the ISO 100 film the grain is about the same as in highlights there. So there is no point for me to use an ISO 400 film which is more expensive and provides lower dynamic range, while it offers only slight advantage in maximum sensitivity.

Sensitivity is one of the areas where digital easily beats film. Where I'm limited to ISO 50-100 with film, good digital cameras can go safely up to ISO 400-800. Additionally, the higher depth of field allows to use one step wider aperture. And finally, image stabilizers become common, which adds further 2-3 steps. Summed up, DSLRs can provide at least 6 EV advantage over film in nature photography.

I've finally managed to process my photos from the last winter. You can look at samples of my photos taken under moon light. They are not good photos but they show how moonlight photography can look like. Note the photos are somewhat shaky because I forgot the remote control at home and had to hold the shutter button by hand for the whole time of exposure.

After using my Olympus C-2100 UZ digital camera for several years exclusively I slowly revive my old film equipment. Despite the great practical advantages of digital cameras such as immediate feedback, in-camera processing, no dust (with a proper camera), no scratches, data safety, low snapshot costs, low weight, etc., there are still some problems. I was very happy with the Olympus camera initially and I learned a lot using it. But with the learning process the camera's drawbacks became apparent: grain replaced by noise and aggressive image processing, too low depth of field replaced by too high depth of field, too low contrast replaced by too high contrast, high sensitivity replaced by inability to take long exposures. I consider the 10x zoom C-2100 lens being quite good, but it has its limits too: it doesn't provide wide angle focal range and it suffers from occasional chromatic aberration.

Ironically, the camera buries itself by teaching me. The clever guys at Olympus have probably even implemented it as a feature -- while the camera costed more than all my previous photographic equipment together, it lasted less than any of the other components. It took only a bit more than 3 years before it started to suffer from serious mechanical problems. So I started to look for a replacement not only because of my new requirements, but also because of possible future complete failure of the made-in-Japan camera.

Compact digital cameras haven't made much progress since Olympus C-2100. The number of pixels increased significantly, but without big impact on the resulting picture quality. The processing algorithms were improved, but that's basically all. It makes no point for me to buy another camera with a small sensor. And good digital cameras are still too expensive (Sony DSC R1 being the cheapest one, but still exceeding what I could reasonably pay).

In this situation I've started to make experiments with my old Praktica-based equipment about a year ago. I hope it can complement the Olympus camera or even to replace it completely for some time in case of its complete failure. One can't resist nostalgia when holding the old equipment in his hands: Solid construction, no batteries needed, the feel of complete control over the camera, listening to the shutter and mirror noise again after the years of silence... But the primary result of this change (not counting changes to one's physical condition caused by carrying the heavy equipment) is that I have to be very careful with taking pictures again. It starts by changing lenses, mounting the camera to a tripod, manual focusing, guessing proper depth of field, considering metering corrections, etc. It takes a lot of time to take a picture, but it's the more amusing part. The tedious part is processing the developed film. I'm not going to make prints at minilab, I want to process the images myself electronically and store them in my computer. And this is no easy thing with film. I'll write more about my experience with this later.

When I upgraded my computer, I wanted to make it available to my family even when I'm sitting in front of it (this happens most of the time). Natural way to allow this is to connect additional terminals to the computer. The simplest, cheapest and power saving kind of terminal consists just of a set of I/O devices, such as a monitor, a keyboard and a mouse or a TV with a remote control.

So I equipped the new computer with two graphics cards, assuming that connecting multiple input and output devices to the computer should be just a matter of having corresponding number of graphics cards and free USB ports available. Big mistake! Never, never underestimate software problems. It took me several months to make the multiseat setup actually working and still not without problems.

The very first problem was that X.Org 7.0 refused to run on the second graphics card at all. This is some mismatch between X.Org 7.0/6.9 and recent Linux kernels. After a lot of experiments and googling I finally found a patch that works for me.

Now I was able to run two different X servers, but only on different Linux consoles, i.e. not accessible in parallel. I followed the very nice Multiseat HOWTO, but it still didn't work -- my X session has always frozen when I started the second instance of the X server sharing the console. After additional experiments and googling I've found it might be worth to try running different video drivers on each of the graphics cards. The two graphics cards I've got in my computer are the same, so I tried to run one of them with the X.Org ATI driver and the other with the ATI proprietary driver. Indeed, I can run two X servers in parallel now. Not without limitiatons: While the free X.Org driver runs fine, the ATI proprietary driver runs only on the first graphics card (it refuses to start on the second card), without 3D acceleration (compilation of the fglrx kernel module failed) and it freezes the computer when one logs out (this is a real problem that I don't understand since the X server is not restarted on logout). Another problem is that X.Org doesn't allow switching to a Linux text console when running multiseat.

An additional interesting observation is that one can't rely even on such basic things like that a keyboard works. My USB keyboard stops working very soon after boot and needs to be unplugged and plugged in again. Then it works fine, but if I do it when X has already been started, the mouse connected to the USB hub built in the keyboard stops working completely. AFAIK there is a lot of problems with USB keyboards on Linux, often without solution. Well, this is so called computer age...

Well, not only proprietary drivers are crappy, they are just more crappy than anything else. Free software sometimes suffers from serious problems too.

I use a dedicated virtual machine to manage my printing services. One of the reasons I've put it on a separate machine is stability: While software on my other machines is updated, the printing server can remain untouched.

Now I know I can't expect that kind of stability from CUPS. I often upgrade my workstation. Suddenly printing from GIMP and PhotoPrint stopped working with the error message saying something like "Bad IPP request". After some attempts to find out what's wrong I've found that my CUPS client is of newer version than the CUPS server. Great -- unless you use the same client and server software version on your network, CUPS may not work. So I had to upgrade the CUPS server, just because a workstation happened to use newer client version.

The CUPS server upgrade wasn't without trouble. Together with the 1.1 -> 1.2 transition the main configuration file was changed. Well, that's OK (only if I wasn't forced to fiddle with new configuration right now because of the client software update!). But I couldn't access the printing server because of some permission problem. After significant amount of time spent on discovering what's wrong I've finally got it: The 'Allow' directive doesn't work with host name, it requires an IP address. Sigh.

So CUPS started to work with my parallel port printer. Not so with the printer connected through USB. It reported to be unable to open the corresponding USB device. Even setting the device permissions to 666 didn't help. I ended up with downgrading CUPS to 1.1 on both the server and client machines.

I've never liked CUPS. CUPS is not a bad idea and it's fine when it happens to work well, but it has been making troubles all the time I use it. From what I've seen for several years of CUPS usage I have to say that Linux printer management is apparently in incompetent hands (not sure whether upstream or in Debian).

My long term observation about GNOME and KDE is that GNOME is stronger in desktop, while KDE is stronger in applications. One of the excellent KDE applications is digiKam.

The most popular free image processing tool, GIMP, hasn't succeeded to become a tool for serious work. Its lack of important features (such as 16-bit color support) and poor user interface make it suitable just for occasional use and perhaps for web designers. Lack of free usable photo processing and management tools has motivated me to develop my own photo processing program as a part of my Springtail Lisp tools. But due to lack of time and zero support from McCLIM developers Springtail didn't provide completely satisfying results.

About a year ago I discovered digiKam. After trying it I've abandoned the Springtail photo application development immediately. Not that digiKam offered all the features present in Springtail and everything I needed, but it provided interesting features, good user interface and was well maintained. It was clear to me that this may be the right tool and it made no sense to invest my effort into development of my own tool instead of helping a promising project.

I can say that digiKam fulfills my expectations and I recommend it to photo enthusiasts who look for a good photo editing and management tool. It can't do everything and there are many features that could be improved, but this is up to us -- we can file bug reports, vote for bugs and make patches. I believe this project is well maintained and it's worth to help it.

ATI graphics cards suck and I can't recommend buying them. I've spent significant amount of time trying to get run their proprietary drivers on Linux and the conclusion is that the X.Org free drivers are dozen times better than those from ATI, despite 3D acceleration and TV-out don't work with my ATI card. Effectively, my new ATI card is a 3D incapable device without TV output.

I don't believe NVidia is much better -- I've once had particularly bad experience with an NVidia graphics card. Intel cards are well supported, but does Intel make anything else than onboard cards? We clearly miss real competition on the hardware market.

I really can't understand the ignorance of hardware vendors. They are incapable to produce stable and well working drivers for Linux. Well, why don't they provide specifications to their devices then and let people make good drivers for free? What's so secret on accessing 3D graphics acceleration or making a printer to print a borderless photo?!

Will Linux and other non-proprietary operating systems still be usable without essential modern hardware features? I doubt. But what's the solution? Current market turns into unbreakable oligopoly in many areas, so the natural market mechanism doesn't work. Open hardware would be the best solution, but it seems this is not something that could become widely accessible in the foreseeable future. Apparently there is not much else to do now than continuing the reverse engineering battle. :-(

KMa s.r.o. -- Levné knihy is a Czech publishing company specialized on publishing and selling cheap books, especially classic literature with expired copyrights. Now they publish cheap movies on DVDs as well, for a price of 3-4 €, that is about 1% of common salary here and easily affordable.

They publish various kinds of movies, including large selection of excellent movies by Ingmar Bergman and Akira Kurosawa. Thanks to them I can watch movies on DVDs for the first time now.

OSA (The Performing and Mechanical Rights Society of Composers, Authors and Publishers) was successful again with their lobbying. The upgrade of Czech copyright law brings great news for them: While it's now illegal to make any copies of a protected work (so you can't make backup copies of your CDs anymore!), we not only still pay fees for each empty CD or DVD but the range of the taxed devices and media was extended. So the law either introduces pure taxes paid to an organization you have nothing to do with or it defines a priori compensation for criminal activities, paid by all the citizens. Both looks pretty absurd to me.

The problem is how to boycott this. Even if you ignore the bastards completely, i.e. don't listen to their music, don't watch their movies, etc., you still have to pay them in case you use photocopy services, buy DVD media, memory cards, music players, printers, recorders and other devices, regardless of the purpose you use them for (such as storing your own data or works).

Perhaps the first non-commercial TV broadcasting has started in Czech Republic about a month ago. It's called TV Noe (Noah TV) and it's a Christian broadcasting focusing on positive values and supposed to be financed mostly by voluntary contributions from its viewers and by broadcasting short messages from sponsors. Unlike other TV broadcasters in Czech Republic (including Czech public TV), TV Noe doesn't broadcast advertisements. This model has already been successfully applied here for more 10 years by Radio Proglas, a Czech Christian radio sponsored almost completely by contributions from its listeners.

TV Noe currently broadcasts only through satellite and in proprietary video formats on Internet, so I can't watch it. But I wish it success as it's a unique and promising project here.

Our second son was born. Photos at http://marek.zamazal.org.

Linux has always been a nice free and stable operating system. But from the user's point of view it was somewhat primitive and lacking some basic features. Perhaps that was one of the primary reasons why GNU continued to develop another operating system, the Hurd.

But things have recently improved a lot. By integrating FUSE into the official Linux distribution and Linux-VServer into Debian Linux kernels, two important Linux limitations are mostly gone.

FUSE allows users to create their own virtual user-space file systems. That means the elegant facility provided by Hurd translators is available in Linux now too. It's finally possible to mount remote directories transparently, to create usable automounters, to implement new file system features in high-level programming languages, etc. and that all without root privileges.

There is still a missing feature though. FUSE currently provides only active translators that require explicit startup and do not survive the next reboot. Passive translators, i.e. permanent translators started automatically when their mount point is accessed are still not available. Hopefully they will be added to Linux too.

Linux-VServer allows you to use several virtual machines on a single hardware. It's something like running new Hurd instance inside another already running Hurd instance. Linux-VServer, unlike hardware emulators, allows separating independent tasks without any significant burden on the hardware -- the CPU, RAM and disk usage overhead is negligible. With your processes running on different virtual machines, you are more protected against both accidental and intentional failures. For instance your web server can always run on a dedicated computer (as it should) without the need to dedicate it actual separate hardware. Then you can safely upgrade each service separately without the danger to damage other services and with the possibility to roll back to the original version immediately.

With Linux-VServer (or similar projects) hardware can be used more efficiently. Instead of having a lot of physical computers being most of the time idle you can build a few bigger physical machines running a lot of virtual computers for many users and uses. I didn't like the single big machine approach before because it required interaction with sysadmins. User: "Would you upgrade Emacs installation there, please?", Sysadmin: "What is it Emacs?", U: "It's a text editor.", S: "I don't use it.", U: "Would you still upgrade its five years old installation, I need new Emacs features.", S: "No, it could break.", U: "Hm, hopefully I won't reach my $HOME quota this time...". With Linux-VServer, the user can safely receive his own virtual computer and run his own operating system of his choice on it without messing with other users (and sysadmins, most of the time).

Linux-VServer is still immature, especially it lacks proper documentation, but nevertheless it's already very useful. Both FUSE and Linux-VServer are promising and give us a hope that a free and usable modern operating system will be available sometimes.

One of the interesting features of the AMD64 X2 architecture is that its declared power consumption is not higher than of single core AMD64 processors running on similar frequencies. So if you perform significant amount of tasks that can be parallelized (e.g. running a build daemon), you can choose between two different advantages of the dual core system: higher performance or reduced power consumption.

The latter should be achievable by running the CPU on half of its standard frequency (using the Cool`n'Quiet technology). This way you may get a high performance system that can be easily dynamically turned into a system with about half the CPU power consumption and performance of a single core system running on the full CPU frequency. Cool. It seems it makes perfect sense to run 'nice make -j3' on a dual core system.