What is the gamma of a Macintosh?
Apple offers no definition of the nonlinearity – or loosely speaking, gamma – that is intrinsic in QuickDraw. But the combination of a default QuickDraw lookup table and a standard monitor causes luminance to represent the 1.8-power of the R, G, and B values presented to QuickDraw. It is wrongly believed that Macintosh computers use monitors whose transfer function is different from the rest of the industry. The unconventional QuickDraw handling of nonlinearity is the root of this misconception. Macintosh coding is shown in the bottom row of the diagram. More detail is available in Poynton’s article Gamma on the Apple Macintosh available on the Internet (Acrobat PDF format, nnn bytes). The transfer of image data in computing involves various transfer functions: at coding, in the framebuffer, at the lookup table, and at the monitor. Strictly speaking the term gamma applies to the exponent of the power function at the monitor. If you use the term loosely, in the case of a Mac you could c
Apple offers no definition of the nonlinearity – or loosely speaking, gamma – that is intrinsic in QuickDraw. But the combination of a default QuickDraw lookup table and a standard monitor causes intensity to represent the 1.8-power of the R, G and B values presented to QuickDraw. It is wrongly believed that Macintosh computers use monitors whose transfer function is different from the rest of the industry. The unconventional QuickDraw handling of nonlinearity is the root of this misconception. Macintosh coding is shown in the bottom row of the diagram. More detail is available [4]. The transfer of image data in computing involves various transfer functions: at coding, in the framebuffer, at the lookup table, and at the monitor. Strictly speaking the term gamma applies to the exponent of the power function at the monitor. If you use the term loosely, in the case of a Mac you could call the gamma 1.4, 1.8 or 2.5 depending which part of the system you were discussing. I recommend using t
