User Guide

GNU Image Manipulation Program
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From The Color Circle: Two axis to define "From" range. The curved arrow in angle lets to recognise "From" axis and "To"
axis of range. Click-drag these axis to change range.
Switch to Clockwise/Counterclockwise: Sets the direction the range is going.
Change Order of Arrows: Inverts From and To axis. This results in an important color change as colors in selection angle
are different.
Select All selects the whole color circle.
From and To boxes display start axis and end axis positions (in rad/PI) which are limiting the selected color range. You
can enter these positions manually or with help of arrow-heads.
To This section options are the same as "From" section ones.
15.3.5.3 Grey Options
Figure 15.27: Base image for Grey Options
Three sectors are defined for Red, Green and Blue with different saturations. Grey and White colors are represented (0% Sat).
In this tab, you can specify how to treat gray. By default, grey is not considered as a color and is not taken in account by the
rotation. Here, you can convert slightly saturated colors into grey and you can also convert grey into color.
Grey Color Circle At center of this color circle is a small "define circle". At center, it represents grey. If you increase grey
threshold progressively, colors with saturation less than this threshold turn to grey.
Then, if you pan the define circle in the color circle, or if you use input boxes, you define Hue and Saturation. This color
will replace all colors you have defined as grey. But result depends on Grey Mode too.
Grey Mode The radio buttons Treat As This and Change As This determine how your previous choices will be treated:
• With Change to this, grey will take the color defined by the define circle directly, without any rotation, whatever its
position in the color circle.
• With Treat as this, grey will take the color defined by the define circle after rotation, according to "From" and "To"
choices you made in the Main tab. With this option, you can select color only in the "From" sector, even if it is not
visible in Grey tab.