GIMP Plug-ins: blur and randomize

(for GIMP version 0.99.28 or later)

randomize version 1.7

blur version 2.0

gpc version 1.4

These plug-in perform various operations on an image, allowing the user to select a percentage of pixels to operate one, and a repeat count. When the percentage is less than 100, the pixels to transform are chosen at random. Variations include: The gpc is a set of GTK+ GUI convenience routines for plug-in writers.

The blur code was that of the original, GUIless blur plug-in. It has been separated back out of the randomize plug-in, with two separate PDB entries so that it may be used in scripts in the old, non-random fashion.

The new plug-ins have a GUI similar to the one shown here, except that the radio buttons for operation are missing, and the title shows the function (blur, random hurl, random pick or random slur).

In any case, for each pixel in the selection or image, whether to change the pixel is decided by picking a random number, weighted by the user's "randomization" percentage. If the random number is in range, the pixel is modified. For blurring, an average is determined from the current and adjacent pixels. (Except for the random factor, the blur code came straight from the original S&P blur plug-in.) Picking one selects the new pixel value at random from the current and adjacent pixels. Hurling assigns a random value to the pixel. Slurring sort of melts downwards; if a pixel is to be slurred, there is an 80% chance the pixel above be used; otherwise, one of the pixels adjacent to the one above is used (even odds as to which it will be).

The random number generator's seed can be explicitly initialized from the current time or by a user value (usually for duplicating a previous effect) by selecting the appropriate radio button.

Picking, hurling and slurring work with any image type. Blurring works only with RGB and grayscale images.

This plug-in's effectiveness varies a lot with the type and clarity of the image being "randomized". To show the differences, I've included examples based on a photo taken with a typical computer-based camera, and an image made by applying the plasma and mosaic plug-ins (in that order) with their default settings.

Hurling more than 75% or so onto an existing image will make the image nearly unrecognizable. By 90% hurl, most images are indistinguishable from random noise.

The repeat count is especially useful with slurring.



Randomizing a Photo
Original [Image?] The photo's a bit blurry to begin with; I'll get a better one scanned in soon, and redo the examples with that.
50% blur [Image?] 100% blur [Image?]
50% pick [Image?] 100% pick [Image?]
Hurled [Image?] Hurling by itself just adds random spots. Here I selected the faceshield area of the helmet, hurled 15%, blurred 100%, picked 100% and blurred 100% to disguise the facial features without destroying the effect of the photo.
Picked 25 times [Image?] This was 100% picked 25 times.
Randomizing a Mosaic
Original image [Image?] This is your basic plasma turned into a mosaic. Both these operations were performed with the plug-ins' defaults. Note that blur 100% is the same as just running the standard blur plug-in.
50% blur [Image?] 100% blur [Image?]
50% pick [Image?] 100% pick [Image?]
Slurred 50 times [Image?] A 50% blur was applied first, then 50 repeats of 75% slur.

Last updated: 03 May 1998

Copyright 1997 Miles O'Neal, Austin, TX. All rights reserved.

Miles O'Neal <> [remove the "XYZZY." to make things work!] c/o RNN / 1705 Oak Forest Dr / Round Rock, TX / 78681-1514