Yet another high pass. I use it to normalize brightness of textures. This script provides two different approaches: grain extract mode (mainly used to remove the effect of vignettes) and soft light mode (for images with sharp lightness transitions, but this mode is not so powerful as grain extract).
After installing, you'll find it in:
Filters/Enhance/High Pass Filter
I created a simple program in WINAPI to generate gradients of the downloaded jpg image files. The principle is simple, if an image is loaded, you can press the left mouse button in a fixed area image window, drag and release in the second section and the program automatically creates a preview of a gradient consisting of a number of segments displayed in the control at the top of the window. By pressing the button with the hand goes to manual mode, where you can add or subtract points on the path drawn by double clicking the left mouse button near a path.
This simple program pulls definitions gradients created in a file. Svg Inkscape and converts them into files gimp gradients GGR. You can just drag the icon svg file an application, which will export the gradients to the files in the program folder, or run the application by clicking on it twice, and acting in accordance with the instructions.
Simple console program made by me to automatic generate random gradient in ggr format. Someday I wonted to do this tutorial here: http://www.eyesontutorials.com/articles/5276/1/Photorealistic-Vinyl-Desi... and I could not do it because GIMP does not have a generator of random gradients. Because I know how to programing I decided to write a console program that generates a random gradient for me.