On Saturday 04 March 2006 06:48 am, Cory Papenfuss wrote: > I got off on the monitor profiling tangent a bit this morning, and > as far as I can tell, nobody gives a crap about linux-land monitor > colorimetry. Argyll allegedly supports two devices, but they're both old > and expensive. Ran across this idea: > > http://wiki.scribus.net/index.php/Proposal_for_Monitor_Profiling > > Basically, it assumes that one can generate an accurate color > profile for a digital camera, and then turn around and use it as a > colorimeter to profile your monitor. > > Does this seem like a reasonable thing to do? I'm sure it's not > as accurate as a puck-like object stuck directly on the screen, but with > minimal ambient light it may be reasonable. The gamut of DSLRs in > particular is comparable to CRT's, no? > > Intriguing... > > -Cory
Cory, This is a very interesting article and in the discussion section for the article I have already made extensive comments. But you raise some interesting points. There is one vendor that is at least a little interested in this market segment but they appear to have concerns that need to be resolved before any progress will be made. The major issue is that the less expensive devices that we are talking about are at least in part implemented in software. This is significantly differnet from devices like the Spectrolino where everything is implemented in the hardware. As a result the vendor(s) need to figure out how to make that software (the drivers or interface library) available to Linux/Unix/BSD users without exposing implementation details. This is not a simple or inexpensive task and there are a lot of issues that they need to deal with to make this possible. In the end I think this can be resolved but the vendors are used to how things work for the Windows market place and are having a very hard time understanding how to deal with the OSS world. You are correct about the devices supported by Argyll but I would have phrased it is as "the devices are either old and difficult to obtain or relatively expensive" since the Spectrolino is still in production but too expensive for many users (over. $3000 list). The ability of current versions of LPROF to generate quality camera profiles is the best it has ever been. But determining the accuracy of the camera profiles generated by it or any other software is at best problematic. This web page http://www.tkupfer.de/imaging/Scan_Profiling.html evaluates a number of profilers including an older version of LPROF and packages from most of the major vendors at the time of the evaluation. The reviewer profiled scanners for the evaluation which is a simpler task than profiling a camera as there are fewer variables. LPROF had by far the lowest delta E numbers of any of the packages evaluated and current version of LPROF is better than the version tested both with respect to delta E numbers and particularly the smoothness of the CLUT curves. I think the question of how much impact ambient light has on the technique is an open question. The author does not state what the ambient light conditions were when capturing the IT8.7 image from the monitor. I believe that this is a critical question and a huge variable that needs to be controlled. There are also a number of other variables that are not discussed in the article that need to be explored and controlled. Most DSLR cameras have way more gamut than a typical CRT and likely more than most if not all currently available display devices. So I don't think that this is an issue with the technique. I also expect that as digital camera technology advances that we will see improved gamut and dynamic range. I don't think it is possible that this technique, or a variation of it, would result in profiles that are as good as those generated using a high quality measuring device. But I think that if everything were done in just the right way it might be possible to get profiles that are significantly better than those generated using LPROF "Rough Monitor profiler". In other words it has the potential to be a good "poor mans" technique and it may be the only option available until/unless one of the hardware vendors starts to provide measurement hardware interface software that works on Linux/Unix/BSD machines. Hal ------------------------------------------------------- This SF.Net email is sponsored by xPML, a groundbreaking scripting language that extends applications into web and mobile media. Attend the live webcast and join the prime developer group breaking into this new coding territory! http://sel.as-us.falkag.net/sel?cmd=lnk&kid=110944&bid=241720&dat=121642 _______________________________________________ Lcms-user mailing list Lcms-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lcms-user
