In order to understand Calman's software properly, one has to understand the complexities of calibrating a display. Calman uses a well-known colorimetric method from the 1950s called CIE XYZ, but instead of measuring the sRGB, it measures the display's aging. The XYZ control, digitized since the early 90s, will produce the closest result but now the calibration software has to compensate for the human eye's perception of color. The aging eye has a smaller Blue-Yellow response and a larger Magenta-Cyan response, so a test is done to see where is the point on the display where the eye sees a maximum of Cyan. (If it's actually a maximum of Magenta and Cyan it means the test is way off.) This point specific spot on the display is called the key. Then, a series of factor dials are adjusted until the results shown by the software look identical (back to baseline) to the standard old-fashioned colorimetric reference CIE XYZ. The term for the result is \"nominal.\"
The method of estimating the display's color performance comes from a book from 1977 called \"Educating the Eye\" by Paul Shewman. It came out in the 1970s and was the last major book on the topic before the rise of color-gamut displays, which did not exist back then. Shewman's methods are very labor-intensive, and the software is attempting to incorporate his methods into the CalMan software.
The Calman software uses the same process, but instead of a reference, it uses the nominal point instead. The other computation that has to happen for a truly accurate colorimetric result comes from the density of the phosphors on the screen, which also has to take into account our individual difference. This is the process that happens for the ColorChecker for SDR, Grayscale, CMS, and HDR measurements. The rest is simply figuring out what color mixing the display is too, how color-efficient the display is, and if the display is capable of the HDR technology. Since the professional user should already be working with CMS and SDR devices, the software tries to automatically correct for as much of the problem as possible. Still, no calibration will ever be as accurate as working with a strict reference like the ColorChecker. 7211a4ac4a