Hello, I ran a calibration/profiling on my notebook's LCD using argyll 1.0.4 and Florian Höch's dispcalGUI, making a LUT profile (matrix profiles were not good on the neutral grayscale quality measure) and using the 512 patch target provided with dispcalGUI. Yhe options were dispcal -v -d1 -c1 -yl -qh -m -t6500 -gs -f0 -a200 -k0 and colprof -v -qh -al The LCD's LUT accuracy is measured to be 8 bit, and the 100-patch profile test gave something like a maximum deviation of 2.8 deltaE and an average of 0.8dE. I can't complain: the Monaco Optix LUT profile was something like 2 or 3 times greater on those measures. The visual improvement in the display is considerable, although these displays are not, obviously, capable of super accurate performance. And the gamut volume is barely more than 55% of sRGB, if I'm to believe the information given by the gamut comparison utility at iccview.de But the remaining problem is this: shadow detail was removed from images when viewed in a color managed application with the video LUT loaded, while it was present when viewed in a non-managed viewer with the video LUT loaded. Initially I hadn't used the ambient light option on dispcal and the difference between RGB(0,0,0) and RGB(5,5,5) patches seemed to be barely perceptible in a color managed program (although a non-managed program displayed them clearly with the monitor calibration curve loaded), even with very dim surroundings. So I tried dispcal -a200 and that seems to improve matters, the difference is perceptible, and RGB(2,2,2) is just barely visible in dim ambient light surrounding the screen. Here's what it does with icclu (I hope I have the options right!): icclu -s 256 -fb -ir "DISPLAY3 2009-11-14 max D6500 min native sRGB 200lx HQ LUT.icm" < 0-9-91-100-Lab-triplets.txt 0.000000 0.000000 0.000000 [Lab] -> Lut -> 1.152313 0.000003 0.000004 [RGB] 1.000000 0.000000 0.000000 [Lab] -> Lut -> 2.514642 1.512020 0.391941 [RGB] 2.000000 0.000000 0.000000 [Lab] -> Lut -> 3.862856 2.998367 0.783878 [RGB] 3.000000 0.000000 0.000000 [Lab] -> Lut -> 5.198951 4.456532 1.171908 [RGB] 4.000000 0.000000 0.000000 [Lab] -> Lut -> 7.631482 6.906010 3.541074 [RGB] 5.000000 0.000000 0.000000 [Lab] -> Lut -> 10.198043 9.635550 6.214755 [RGB] 6.000000 0.000000 0.000000 [Lab] -> Lut -> 12.893085 12.361375 9.058784 [RGB] 7.000000 0.000000 0.000000 [Lab] -> Lut -> 15.286773 14.854340 11.452832 [RGB] 8.000000 0.000000 0.000000 [Lab] -> Lut -> 17.498889 17.065008 13.848722 [RGB] 9.000000 0.000000 0.000000 [Lab] -> Lut -> 19.906143 19.290144 16.274801 [RGB] 10.000000 0.000000 0.000000 [Lab] -> Lut -> 22.101790 21.502601 18.475830 [RGB] Then I read the mailing list exchange between Gustavsen and Gill //www.freelists.org/post/argyllcms/In-the-shadowlands : <START QUOTE> Lars Tore Gustavsen wrote: [...] In practical viewing it means the test image posted in another e-mail http://www.fc-prints.de/fileadmin/daten/fcPrints_Testbild_100ppi.jpg, none of the numbers below 5 or so at top right are visible in firefox with a lut based profile. I can see all the black numbers in a not color aware viewer, but with my calibration loaded. If I view the same image with a perceptual rendering intent and a lut based profile it looks almost fine. A matrix profile also handles this well but the overall accuracy elsewhere are much poorer. [...] Thanks When I look at the above mentioned image without my calibration loaded in a not color aware browser I can see the numbers down to 5-4. When I load the calibration curve, still viewing in the same viewer, I get all numbers down to 1. When I enable relative colormetric in a color aware viewer and with my calibration loaded I'm back to five. Perceptual give me 2-1 on the above image. It was wrong what I wrote about the matrix profile in my last e-mail. The matrix profile gives me 5. I created a collections with screenshoots, but I don't think they can view the real truth on any other monitors than mine. http://mulebakken.net/div/monitor-f.png Gill replied: Right, so it sounds like the calibration is working OK, and that the native behaviour of the display is to have a "dead" region just above zero (not unusual). Gill cited Gustavsen "When I enable relative colormetric in a color aware viewer and with my calibration loaded I'm back to five." and replied: Presumably this is with the profile created with the calibration in place. This is also not unexpected when the source colorspace is idealised (such as sRGB, AdobeRGB etc., having a zero XYZ/L* for RGB = 0), and no proper luminance range mapping is being performed in the profiling linking (typical of relative colorimetric or dumb perceptual). This is what black point compensation or true perceptual gamut mapping addresses. <END QUOTE> So, was the dispcal ambient light -a option the right correction to use to solve the problem of disappearing color-managed shadow detail? How is it possible to get those other intents into the generated profile so I can try out the gamut mapping method? At the moment, the LUT profile just has the "relative colorimetric" tables in it. I use a photo editor that uses the LittleCMS color mangement module and that gives a choice of the perceptual, absolute or relative colorimetric, relative colorimetric w/BPC, or saturation intents. "Perceptual" is the recommended setting, and I'm assuming LittleCMS just uses the relative colorimetric tables verbatim, since nothing changes visually in the test fc-prints.de digital file mentioned in Gustavsen's email when I switch intents. What options do I give colprof to generate the other tables? I'm uncertain: what to specify as a reasonable "source color space" -S option that would enclose most of the usual colors in digital photography images? I.e. something a little larger than sRGB, but not too large? Or use the LCD manufacturer's supplied icc profile (without calibration curve) for the LCD panel, that the iccview.de comparision measures as 80% of the sRGB volume--should I use that? Or should I use some reasonable profile for reflective media (e.g. a typical inkjet printer)--but as I'm not looking at reflective media while editing pictures, how can that be a correct choice? Any enlightenment much appreciated! Sorry for the length of this email, try not to quote it wholesale in any replies.