The gamma option specifies the gamma setting for the image. Gamma settings are used to emphasize the distinction between shades of color so the human eye can discern them properly. If an image is too bright or too dark, you can use this option to adjust the lighting appropriately. To lighten an image, assign a lower value to the gamma option. To darken an image, assign a higher value. The default value is 2.2.
Gamma correction does not occur during the encoding process; instead, this value is stored in the output DjVu® file and is used by the DjVu Browser Plug-in at the time of rendering.
Supporting commands:
documenttodjvu, phototodjvu