For more information and a full description of these keys, see Image adjustment keys.
Use the following keys to increase and decrease the luminance:
Adjusting saturation
Saturation is the amount of color vibrance in the image. The range of saturation settings in FCheck is between -100 and +100.
Adjusting gamma
Gamma is the overall brightness of an image. Changes to gamma not only adjusts the brightness, but also adjusts ratios of colors in the image. The range of gamma settings in FCheck is between -100 and +100. Use the following keys to increase and decrease gamma.
Decreasing gamma darkens the color tones in an image. Overall brightness is also decreased.
(Mac OS X) You can also use the Info window to adjust the values.
A specific gamma value can also be entered by typing fcheck -G <gamma> into the command prompt and opening an image/sequence. <gamma> represents the gamma value wanted.
By supplying the correct gamma value using the -G option on the command line, you can display the image as intended. This is one of the most useful command line options in FCheck acting as a gamma repair tool.