Images manipulated with GIMP

Try to change the background color by clicking on one of the color squares! This selection of 16 colors out of 16777216 possible ones is, of course, arbitrary. The current color is #222222 in triple hexadecimal representation, Value = 34.
Value = √(.241 R² + .691 G² + .068 B²) where R, G and B are the decimal values of the three componets of the page’s background color. It is 0 for black and 256 for white. The Value determines the text color of the page. For Value > 128 the text color is set to black, otherweise to white.

Four Trees

This image was generated by a recursive PostScript. The root of each tree bifurcates while changing scale and color. GIMP was only used to convert the vector graphic to a pixel graphic, to make the background transparent and to convert the image to PNG. Try to change the background color!

Randolph in his lab

On the original photograph, my friend Randolph seemed to be somewhat lost in his electronics lab. To emphasize my friend, the lens tool was applied. To de-emphasize his surroundings, the background was de-saturated, slightly blurred and its contrast reduced.

Gebhard playing guitar

The black and white photograph of my friend Gebhard playing his Les Paul guitar was posterized, i.e. the gray scale is reduced to 4 levels.

In the morning In the afternoon

The two pictures of the Black Canyon of the Gunnison National Park (Pulpit Rock Overlook) in Colorado were taken on subsequent days, the left one on an afternoon, the right one the following morning. Neither one is fully satisfying. The image below is a blending of the two. Using Gimp’s layer technique, the bottom layer is the left picture, and the top layer the right picture. Since the two pictures were taken from points a few meters apart, the foregrounds are different. In order to keep the foreground of the left picture, the foreground was cut away on the top layer. After carefully aligning the two layers, the opacity of the top layer was set to 12%, and the two layers were merged. This resulted in enhancing the fabric of the blue-gray north rim side of the gorge while preserving the back light effect of the left picture. In a similar manner, the sky was taken from the right picture. For photographic details, see comments at the bottom of page More pictures of National Parks.

Black Canyon
A country Alley

A photograph of a country alley on a late autumn afternoon is partially solarized. Read the documentation of how this is done and view a sequence of images that show the progress of the transformation step by step.

This is a background pattern (two tiles placed side by side on this page). The raw material is an image of the sun in extreme ultraviolet light (to be found in the NSSDC Photo Gallery). The most interesting features of the sun are in the upper left corner. This part of the sun was duplicated and rotated 180 degrees, making the image point symmetric with respect to the center of the sun. Applying the seamless tool makes the image suitable as a tiled background. Finally, the image was scaled down to 505 x 505 pixels, sharpened and converted to PNG.

Additive Color System - Subtractive Color System

Left: The Additive Color System. Red, green and blue blend to yellow, cyan, magenta and white. Right: The Subtractive Color System. Cyan, magenta and yellow blend to blue, red, green and black. Gimp’s additive and subtractive blending modes make it easy to create images like these. Actually, only the left image was created using additive blending, the right image was made by inverting the left one.

The right and left moving rainbows were created with a PHP script and converted to animated GIFs with Gimp.

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The blinking Linux Penguin and the blinking Gimp Wilber on top of this page are also animated GIFs created with Gimp.

Credit for the Linux Penguin goes to Neal Tucker. Copyright 2017 by G.W.Schnell. All rights reserved.
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