GIMP Plugin Registry

Easily map colours from a source colour to a target colour. Very effective for matching skin tones across images or between people.

Relatively quick (but not earth shattering). It doesn't work with grayscale or indexed images. Has preview, works with selections and layers, etc. Very, easy to use, and quite useful for portraits or recolouring graphics.

A demonstration: Lenna's face is mapped to the colour of the feather on her hat. This was done by selecting a colour from her face, then selecting a colour from the feather.  read more »

RSS Lightsaber (or LSE) is a simple script for creating lightsaber effect in picture. The script base on my own algorithm.
Features:

• Fast script's execution.
• Independent setting for blur size of the lightsaber's core and glow around saber.
• Some features to provide correct effects on extra large photos (above 20 Mp).

The basic documentation is inside archive.  read more »

Creates a picture which is a duplication of the current picture blured as background,
and the current picture itself reduce with a border and shadow around it as foreground

Example:
Original picture :
Result picture :

This script generates two adjustment layers from the two layers on the top, A is the original image layer, B the modified (e.g. sharpened) one on top:
A - B = C
B - A = D
A - C + D = B  read more »

This script inverse the visibility of the active layer. It is very useful because you can give it a short cut and use the mouse only on your image!

This script set all layers visible or invisible. Don't download it if you have downloaded Script-fu-yin-yang.zip.

This script create a yin-yang figure inside an image. In the package there are : script-fu-yin-yang.scm and all-visible-or-all-invisible.scm (because the first script depends of the second script).

Takes an image, makes four 1/4 scale copies, and reflects them about vertical and horizontal axes to achieve a four-fold symmetry.

Note: As well as being atrociously inefficient (eg, by scaling the same image four times, instead of making copies after the first scaling), this code does substantially less than the "Small Tiles" dialog (which comes standard in Gimp in /Filters/Map)

Provides a kind of poor-man's HDR (high dynamic range). It doesn't actually increase the dynamic range; in fact, it decreases it, overall, but in a way that maintains local contrast. But this gives you some headroom to increase the contrast of the image overall, thus enhancing the local contrast.