Summary: Data from the red-, green-, and blue-sensitive receptors of a camera sensor must be converted to a standard color space in order for images to be displayed properly. The CIE 1931 XYZ space, which encompasses the entire gamut of human color vision, serves as an intermediate between camera raw RGB and practical color spaces such as sRGB and AdobeRGB. The process of converting camera raw data to XYZ coordinates is explained. Empirically, the conversion seems never to be perfect. Color difference metrics (ΔΕ) are reviewed, and several color pairs designed to be near the threshold of just noticeable difference are illustrated. Reproduction of a 24-patch Color Checker Classic by a Sony A6300 camera is evaluated. Even with the best transformation investigated, the colors reproduced by the A6300 are generally distinguishable from their Color Checker standards. Camera profiling is the process of finding a set of linear equations that transform camera raw data to XYZ coordinates. The data necessary for constructing a profile are extracted from an A6300 raw image, and the transformation equations are estimated by multiple linear regression.
Key words: Sony A6300, Canon 60D, sensor spectral sensitivity, camera calibration, camera profile, multiple regression, Luther condition, CIE 1931 color matching functions, CIE XYZ color model, Color Checker Classic, RawDigger, Delta E, CIEDE2000, CIE94, CIE76, CMC, CMC(l:c), just noticeable difference, JND, BabelColor, Bruce Lindbloom
