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diff --git a/doc/calvschar.html b/doc/calvschar.html new file mode 100644 index 0000000..f194d79 --- /dev/null +++ b/doc/calvschar.html @@ -0,0 +1,62 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> +<html> + <head> + <title>Calibration vs. Characterization</title> + <meta http-equiv="content-type" content="text/html; + charset=ISO-8859-1"> + </head> + <body> + <h2 style="text-decoration: underline; font-weight: bold;">Calibration +vs. + + Characterization<br> + </h2> + Some of the terminology can be confusing. Many people are initially + confused about the difference between <span style="font-weight: + bold;">Calibration</span> and <span style="font-weight: bold;">Characterization</span>.<br> + <h3>What is Calibration ?</h3> + "Calibration" is a short hand Graphic Arts term for adjusting a + devices behavior to meet calibration targets.<br> + Calibration is the process of modifying the color behavior of a + device. This is typically done using two mechanisms:<br> + 1) Changing controls or internal settings that it + has.<br> + 2) Applying curves to its color channels.<br> + <br> + The idea of calibration is to put a device is a defined state with + regard to its color response. Often this is used as a day to day + means of maintaining reproducible behavior. Calibration is often the + most practical way of setting parameters such as white point and + brightness of displays. Typically calibration will be stored in + device or systems specific file formats that record the device + settings and/or per channel calibration curves.<br> + <h3>What is Characterization ?</h3> + Characterization (or <span style="font-weight: bold;">profiling</span>) + is <span style="text-decoration: underline;">recording</span> the + way a device reproduces or responds to color. Typically the result + is stored in a device <span style="font-weight: bold;">ICC</span> + profile. Such a profile does not in itself modify color in any way. + What it does is allow a system such as a CMM (Color Management + Module) or color aware application to modify color when combined + with another device profile. Only by knowing the characteristics of + two devices or colorspaces, can a way of transferring color from one + device representation to another be achieved.<br> + <br> + Note that a characterization (profile) will only be valid for a + device if it is in the same state of calibration as it was when it + was characterized.<br> + <h3>What about display calibration and profiles ?</h3> + In the case of display profiles there is some additional confusion + because often the <span style="font-weight: bold;">calibration</span> + information is stored in the <span style="font-weight: bold;">profile</span> + for convenience. By convention it is stored in a tag called the + 'vcgt' tag. Although it is stored in the profile, none of the normal + <span style="font-weight: bold;">ICC</span> based tools or + applications are aware of it, or do anything with it, it is just + "along for the ride". Similarly, typical display calibration tools + and applications will not be aware of, or do anything with the ICC + characterization (profile) information.<br> + <br> + <br> + </body> +</html> |