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+--- Thread: Gimp Color Pixel Degrayscaler Tool (/Thread-Gimp-Color-Pixel-Degrayscaler-Tool)
Gimp Color Pixel Degrayscaler Tool - mathewbailey08 - 04-09-2025
[attachment=13366]
I made a color pixel degrayscaler tool for Gimp in 3.0.2/. It finds basic colors (R,G,B,C,M,Y) in hue,saturation & value of pixels prior to grayscale conversion
by looking at value of grayscale pixels & matching them to non-grayscaled pixels in above mentioned colors so they can checked for RGB & LCH channel values.
Gimp Color Pixel Degrayscaler Tool
What It Does
Finds basic colors (R,G,B,C,M,Y) in hue,saturation & value of pixels prior to grayscale conversion/full
color desaturation by looking at value of grayscale pixels & matching them to non-grayscaled/non-desaturated
pixels in above mentioned colorsfor checking the RGB & LCH channel values,plus how to colorize grayscale images using this tool.
File Format
Image is in XCF format.
How To Use
Download or save file,then open in Gimp as XCF under the ghsv1.xcf file name (grayscale,hue,saturation,value for short)
After opening in Gimp,make two duplicate images & close original. Select second duplicate
image,click Image & convert to grayscale,copy grayscale duplicate & paste it
as layer in place to first duplicate image. Zoom to 1600%,scroll fully up
then fully left with eye on background copy layer off. Use horizontal
& vertical position scales in image window (top & left edges) & in bottom left of image window,
pixel position numbers with px selected. Image should appear as shown as follows:
Beginning at 0 vertical position,grayscale value stripe,(gray value of 0 to 255)followed by two hue stripes,
RGBCMY stripes for saturation,RGBCMY stripes for value. Color picker tool should be set
to example,foreground color with use info window checked. Use select by color &
click on position (horizontal image scale) of grayscale stripe value pixel matching
the position to locate value of pixel in your grayscale image as shown after
selecting background copy as highlighted. Make certain that select by color tool
is set to composite & threshold set to 0.0 with other options such as antialiasing
for example unchecked before doing above. Scroll right until highlighted selection areas
in stripes are seen.(ex.91,3 referring to horizontal & vertical positions
of selected areas) & select background layer if you're colorizing your grayscale image
after converting it to RGB,then use color picker in the mentioned highlighted selection areas.
Colorizing with Gimp Color Pixel Degrayscaler Tool
I devised a way to colorize grayscale images after duplicating & converting them to RGB.
It uses a checkerboard pattern in a 3 by 3 pixel image. Use File,New & set the vertical
& horizontal number of pixels to 3. Zoom to 1600% & scroll to upper left corner.
The three rows in the checkerboard pattern is follows: top row: RGB,
middle row:GBR,bottom row:BRG. Don't forget to set pencil/brush tool to pencil & pixel size to 1 for each of the nine pixels in the pattern.
You can copy the pixel colors from the top row with the color picker,then pencil, & use it with the pencil
for the middle & bottom rows of pixels. Next,set the ellipse/rectangle tool to rectangle & draw a 3 by 3 pixel
square around the pattern. Copy it then use the pattern image in edit to transfer it to the highlighted selection
areas in the RGB converted duplicate of the grayscale image you're coloring. To begin coloring the mentioned grayscale image,
zoom to 1600% as before & again scroll to the upper left corner & select the first pixel with select by color
& use the pattern image in edit as above. This is for Gimp 3 but can be used in the 2.10 versions.
To separately change the red,green & blue pixels in the pattern,for example, click with color select on the red
pixels in the mentioned checkerboard using "Use select by color & click on position(horizontal image scale)..."
as above in the tool image & repeat the procedure for the green & blue pixels in the checkerboard. (forgot to mention
you need to use bucket fill set on fill whole image/selection when separately changing the red,green & blue pixel colors
in the checkerboard.
I hope someone can speed up this coloring procedure by automating what parts of it can be automated & doing things manually
for the rest of it. This is not an AI tool. For example I uploaded a solid red image converted to grayscale & some AI's,even online don't properly convert the image
to the correct color for R255,G0,B0 values.
RE: Gimp Color Pixel Degrayscaler Tool - Ofnuts - 04-10-2025
I don't think anyone if going to follow such a wall of text without some illustrations.
Also, when you go from 16 million colors to 256, you lose some information, and several color combos with very different hues result is the same grayscale value, so how do you go back to the right tint? For instance, if you do `Color > Desaturate > Desaturate (Luminance) on this image, you get a very narrow range of gray (24 values):
[attachment=13371]
What kind of image do you get back?
RE: Gimp Color Pixel Degrayscaler Tool - denzjos - 04-11-2025
Without a photo before / after, I don't know if I understand it, but you want to do something like 'graphic color reverse engineering'. I don't know if you used graphic tools in Gimp or a well-known plugin G'Mic-Qt to experiment with black and white/color images? In G'Mic-Qt it is also easy to use CLUTs to manipulate colors in an image/photo.
https://www.gimp-forum.net/Thread-LUT-s-lookup-tables-load-or-make-and-use?highlight=lut%27s
https://www.gimp-forum.net/Thread-Difficulty-Matching-Colours?highlight=denzjos
https://graphicdesign.stackexchange.com/questions/162951/how-can-i-fix-colors-in-an-image-using-target-colors-gimp