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author | Jörg Frings-Fürst <debian@jff-webhosting.net> | 2014-09-01 13:56:46 +0200 |
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committer | Jörg Frings-Fürst <debian@jff-webhosting.net> | 2014-09-01 13:56:46 +0200 |
commit | 22f703cab05b7cd368f4de9e03991b7664dc5022 (patch) | |
tree | 6f4d50beaa42328e24b1c6b56b6ec059e4ef21a5 /doc/evalInputTargets.html |
Initial import of argyll version 1.5.1-8debian/1.5.1-8
Diffstat (limited to 'doc/evalInputTargets.html')
-rw-r--r-- | doc/evalInputTargets.html | 61 |
1 files changed, 61 insertions, 0 deletions
diff --git a/doc/evalInputTargets.html b/doc/evalInputTargets.html new file mode 100644 index 0000000..91a38f1 --- /dev/null +++ b/doc/evalInputTargets.html @@ -0,0 +1,61 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> +<html> +<head> + <title>Evauating Input Targets</title> + <meta http-equiv="content-type" + content="text/html; charset=ISO-8859-1"> + <meta content="Graeme Gill" name="author"> +</head> +<body> +<h2 style="text-decoration: underline; font-weight: bold;">Evaluating +input targets<br> +</h2> +There are a variety of color profiling targets available for +characterizing input targets, and it is sometimes hard to decide which +one will be best for your particular purpose. Listed here are some +criteria to evaluate:<br> +<h4>Color gamut</h4> +The resulting profile will only be accurate between or near the color +values contained on the chart. This means that if the colors you are +actually processing with your device go outside the gamut of your test +chart, the color values will have been extrapolated by the profile, and +are therefore likely to be not very accurate. <br> +<h4>Color Resolution</h4> +The profile will be most accurate for colors that are near those +contained on the chart. This means that the more closely and evenly +spaced within the color gamut the value of<br> +the test chart are, the more accurate overall the chart will be. So +typically the greater the number of test values, the better.<br> +<h4>Dynamic range and White point</h4> +Similar to color gamut, the profile will only be accurate over the +range of lightness levels exercised by the chart. At the dark end the +ideal black test value will be a light trap. At the white end the ideal +white test value would be the perfect 100% reflective diffuser. In +practice there is another consideration, which is that by default the +white point of the profile is set by the white value of the test chart, +and any values over this may be clipped by the profile. So ideally the +white patches should represent the white value of the work you will be +using the input device for.<br> +<h4>Spectral similarity</h4> +One of the fundamental problems with colorimetrically characterizing +input devices, is that typically input devices don't have the same +spectral sensitivity as a human observer. This means that it "sees" +color differently, and that there is no way to perfectly compensate for +this in a device profile. [There will be some spectral values that look +the same to the device but appear different to us, and visa-versa.] A +colorimetric profile will best compensate for such differences when the +target test colors have the same spectral reflectance characteristics +as the the intended work. What this translates to is that you will get +best results when the test chart uses a similar printing process to +whatever work you will be using the input device for. So if you are +intending to scan photographic prints, you should use a photographic +based test chart. If you were scanning artworks, then you should use a +test chart that has pigments that are similar to paint used on such +artworks, etc. When characterizing camera's, an additional source of +spectral differences is the illuminating light source used. Once again, +it will be best to choose a light source to characterize the camera +that is going to be most similar to the light source you will typically +shoot photographs under. <br> +<br> +</body> +</html> |