Gamma values in different color spaces

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The actual process of gamma correction goes largely unnoticed by the user. If you save directly in the camera as .jpeg, the manufacturer has set all parameters for you. Although convenient, this removes your influence on the process. If you are using the .raw workflow, you can either directly or indirectly influence the gamma value, depending on the .raw converter. Directly via a separate adjustment option. Indirectly via the choice of the working color space to be used. Typically, the .raw converter’s preview window displays a gamma-corrected image, and the various menu settings apply to the uncorrected linear data. This eliminates rounding errors, a rare occurrence when calculating corrected data.

In working color spaces today, we almost always find gamma values of 1.8 or 2.2. Color spaces with a gamma of 1.8 are mainly used in prepress since they simulate the dot gain quite well. – The monitors connected to an older Macintosh computer maintained a gamma value of only 1.8 because the QuickDraw graphics system specified this unusual transfer function. This simulated the dot gain of offset printing so well that no color management was necessary. That’s why MACs became the quasi-standard in the early days of computer-based publishing! Users prefer a gamma of 2.2 when working on a monitor. At present, the trend is to replace gamma with the brightness distribution of the Lab color space (L*), which corresponds to the perception of the human eye.

AdobeRGB has a fixed gamma value of 2.2, which, however, leads to information losses for colors with low brightness. Therefore, the brightness range L*=0 to L*=3 occupies approximately 10% of the AdobeRGB color space, primarily containing noise rather than information.

sRGB is designated with a gamma value of 2.2, but in the shadows this color space has an almost linear gamma.

eciRGB_v1 and ColorMatchRGB have a gamma of 1.8, but near the black point they are almost linear. This avoids the loss of information mentioned above.

eciRGB_v2 and L*-RGB have no gamma value but a visually linear gradation. This implies that the gray axis has visually equal distances, which in turn leads to visually equal distances on the color axes.

Next Subject contrast and exposure range

Main Contrast

Previous Gamma correction the third – distribution of brightness values on 8 bits

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