Adjust the RGB channels of the current image or the selected region.
R, G and B are the channel offsets, from -255 to +255.
Negative values darken all the pixels in the image. Positive values lighten all pixels in the image. To darken colors use IntensityRGBAll (-10, -10, -10). To lighten colors use IntensityRGBAll (10, 10, 10).
Also see AdjustBrightnessContrastSaturation which uses a non-linear LUT to adjust the pixel colors. IntensityRGBAll adjusts the pixel colors by adding or subtracting the R, G, B values of each pixel in the image.