The ColorChecker Classic chart is a rectangular card measuring about , or in its original incarnation about , an aspect ratio approximately the same as that of
35 mm film. It includes 24 patches in a 4 × 6 grid, each slightly under square, made of
matte paint applied to smooth paper, and surrounded by a black border. Six of the patches form a uniform gray
lightness scale, and another six are
primary colors typical of chemical photographic processes –
red,
green,
blue,
cyan,
magenta, and
yellow. The remaining colors include approximations of medium light and medium dark
human skin, blue
sky, the front of a typical
leaf, and a blue
chicory flower. The rest were chosen arbitrarily to represent a gamut "of general interest and utility for test purposes", though the
orange and yellow patches are similarly colored to typical
oranges and
lemons. There is also a ColorCheckerPassport, a smaller version of the ColorChecker Classic with the same 24 chips but in a tri-fold version with some additional patches on two of the pages. Its dimensions are 125mm (H) × 90mm (W) × 9mm (T). The pigments for ColorCheckerPassport were modified in November 2014, so the current available cards do not have exactly the same carnation, and hence RGB numbers, as before, and particularly are not the ones provided on next section. == Colors ==