User Guide

GNU Image Manipulation Program
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Figure 15.28: Grey Mode
The small circle is on yellow and mode is "Change to this". Blue has changed to yellow. Note that Grey and White did so too.
Gray Threshold
Figure 15.29: Gray Threshold
Grey-threshold is 0.25: the blue sector (sat 0.25) has turned to Grey (Note that Grey and White, that are 0% Sat., are not
concerned).
You specify there how much saturation will be considered grey. By increasing progressively saturation, you will see an
enlarging circle in color circle and enlarging selected areas in Preview if "Continuous update" is checked. In a black to
white gradient,you can see enlarging color replacement as you increase threshold very slowly.