UPDATE: Now available on gimpscripts.com


I thought this would be good to have sometime i want many random colors before i call the Auto Hatch Layers script
this is version 1(simple colorize)

version 2 is below, scroll down.
It'll be available under Script-Fu-> Auto Colorize




a test


then called the hatch script

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The script above just does colorization it doesn't consider perceived lightness.
This version calculates perceived lightness and picks a random color with the same perceived lightness.
So if you were to gray scale mode it it looks like gray scale mode of the original image.
I am still experimenting around but this one looks much i better i think than the version above.
this is version 2(colorized based on perceived brightness)

It'll be available under Script-Fu -> Auto colorize


here's a sample of 15 colors, then hatched.

here's another sample...
source image:
after auto-colorize of 12 colors


Because it is random, each time you run this script, you'll get a different result.

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this is version 3 of the script(primary color variations)

available under Script-Fu -> Auto colorize
It was aimed toward producing a generally variations of primary colors (aimed toward the RAP[random art prompt of Primary colors])


What the script does is it tries from highest value of when luminance is less than 1/3 of the maximum it tries to use maximum blue values and then random values of red and green until it finds variation of blue that has the same luminance as original.
When luminance is the middle 3rd chunk it tries maximum red values and other random values of blue and green.
When luminance is the top 3rd chunk it tries maximum green values and other random values of red and green.
Because it has to seek for colors of same luminance based on random values, this script might take a while on darker colors, at times it seems like it's stalling, it's not let it do its work.
Here's an example, it's generally blue red and green but there are slight variations of each of these colors.

limey Audrey Hepburn


and limey John Lennon...
I lucked out and got the blues (cold colors) to go generally in the dark and warmer colors in the bright..so I really like how this one turned out.

I couldn't add more than 3 attachments.

this is version 4 (true to how gimp converts to grayscale mode, aim toward generally primary colors)

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this is version 5(true to how gimp converts to grayscale mode, random colors)

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this is version 6(based on wikipedia's coefficients of how to convert to gray scale)

so for those that have tried all 5 versions
which one do you like best?
from the preview of my examples i think i like version 5 best.

Hello Trandoductin - thanks for the scripts, they keep coming at a hell of a rate

I do though have a question/observation for you - I ran my first AutoColourise with five colours ...



... terrific outcome; so I repasted the owl into the same canvas and proceeded to run AutoColourise this time with ten colours ...



... not such a good outcome; there are three layers ( ID by red dots) where the colour fills the canvas.

This type of outcome is repeatable so should I not rerun the script within the same canvas or is there perhaps a problem when I do?

awesome glad you're trying it out.
I wouldn't recommend you trying to run the script again with different number of colors.
It apply changes to your original layer because it changes the color mode to indexed colors and back to RGB reducing the number of colors...it's best to control-Z the whole effect and try another number of colors (that's what i was doing when i was testing it).

just playing with my script, i thought what if i use make visible layer from the colorization and use that as a layer of to play around with.
1. Original

2. Result from running script

3. Result when i use 2. as a layer on top (set to mode:Color) and opacity at 50%

4. Result when I use 2. as a layer on top (set to mode:Soft Light) opacity 100%


Here's another play.
1. Original

2. Result from running script

3. Result when use #2 as layer on top (set to mode: Soft Light)

true to wikipedia calculations of gray scale but made a change so that it wouldn't take a long time on dark and bright colors (previous scripts did random colorization that took a long time on dark and bright colors because the chance of randomly hitting a really dark color is rare same as really bright ones).
version 6 (with fixed long delay bug on very dark/bright colors)

I like most of your renditions but particularly the first one of John Lennon. These look like interesting scripts but alas as I’m running gimp 2.6 on a 9 year old computer I can’t try them out, I really must get around to upgrading

You should upgrade today. it takes like 5 minutes.

I find it fun to apply this to existing paintings.
source image: https://www.facebook.com/AcrylicPaintingClub/photos/a.123636317799702.26645.118809331615734/458315690998428/?type=1&theater


applied random colorization and used that as softlight layer


another try at the black and white image of john lennon



another painting source: https://www.facebook.com/AcrylicPaintingClub/photos/a.123636317799702.26645.118809331615734/458315674331763/

applied colorization and softlit

auto-random colorize v.6



original photo by eveliddell

only 5 colors...so modest.

Your scripts and their potential are intriguing me .. I got five separate images of our Circular Quay in Sydney starting from European settlement through to today, ran them all against V6 of your script using 10 colours, then assembled them as a collage.



Then ran it through lighting effects with a bump ...



Then ran it again with both bump and an e-map



... so thank you again for these scripts and I have not yet had a real chance to play with the hatching versions.

Very creative, nice result oldmangrumpy.

nice to see you're using it as part of your creative work.... collages are always cool.

I'm not an expert with scheme but shouldn’t the script be set to not alter all layers? If you duplicate a layer, select the new layer and run the script the original layer seems to get affected as well or am I daft (and I don't mean normally, although there is a good chance of that)?

I think when I reduce down to like say 5 colors it does it to the whole image so i wouldn't know how to keep the active layer unchanged.

a bypass of the problem could be USING A NEW IMAGE to perform the whole process

okay so I made to create a new image instead of working on existing one. and added flatten new image option.

this is version 8
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It's moved to Script-Fu/Create New/Auto Colorize


here's a sample run
1. original

2. script created this (setting of 255 colors)

3. used #2 as a soft-light layer on #1 (original)

4. blurred soft-light layer