Colors Manipulation performs exchange of red, green and blue channels of particular image. There are also functions to perform thresholding, color casting and color reduction. Color reduction uses neural network color quantizer, for fast and accurate color reduction.

Red-Green action simply swaps values of Red and Green channel

Green-Blue action swaps values of Green and Blue channels.

Blue-Red
action swaps values of Blue and Red channels.

Max RG action replaces both Red and Green channel values with maximum value of those two channels.
For example: R=20 G=100 B=23; Resulting pixel: R=100 G=100 B=23, because G=MAX(R,G);

Max GB is the same as above, except that now Green and Blue channel values are replaced by maximum value of those two channels.

Max BR is the same as above, except that now Blue and Red channel values are replaced by maximum value of those two channels.

Max RGB action actually converts color image to grayscale image by replacing all channel values with value that is maximum of those three channels.
For example: R=20 G=240 B=100; Resulting pixel: R=240 G=240 B=240, because G=MAX(R,G,B);

Min RG is similar to Max RG, except that Red and Green channel values are replaced this time by minimum value of those two channels.

Min GB action replaces Green and Blue channel values by minimum value of those two channels.

Min BR action replaces Blue and Red channel values by minimum value of those two channels.

Min RGB action actually converts color image to grayscale image by replacing all channel values with value that is minimum of those three channels.
When applying Max RGB the resultant grayscale image is bright, while applying Min RGB, the resultant image is darker.

MinMax action swaps channel values between MinVal channel and MaxVal channel.
For example: R=20 G= 30 B=140; Resultant pixel: R=140 G=30 B=20; As you can see the Green channel was unaffected because it is MidVal channel.

Circular action circularly exchanges channel values on pixel. That is : R->B, B->G, G->R; Applying this action three times you will again return to original image.

Foreground action replaces all pixels with foreground color. Without color restriction, this action is actually simple drawing. Using color restriction where RGB = BACKGROUND color (+/- Epsilon) replaces background color with foreground.

Background action replaces all pixels with background color. Without color restriction, this action is actually simple drawing. Using color restriction where RGB = FOREGROUND color (+/- Epsilon) replaces foreground color with background.

Cast colors replaces all colors in the range (background color, foreground color) with cast color, chosen from color selection dialog.

Thresholds replaces all colors lower or equal to background color with this color. All colors higher then foreground color are replaced with this color.

Reduction action reduces colors number to number specified in edit field on the bottom of this panel. This action plays very important role in web graphics, to ensure fast image loading. This action can be applied only to whole image.

Applying Colors Manipulation

If you want to apply Colors Manipulation on whole image, after choosing the method, simply press Image button and action will be applied to whole image.

You can apply Colors Manipulation through brush movement, contour and mask as well. For shape selection and brush movement refer to Shapes and Brushes section.

NOTE:
Color reduction can not be performed through brush movement, only to whole image.
Resultant image is affected by all previously set
Global parameters.

Example of using color exchange in conjunction with color restriction. On the left side is original picture, on the right side is processed picture. Click on picture to enlarge.