GIMP Version: 2.8.14
Operating System: Windows
GIMP Experience: Intermediate Level

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Hi, Is there a way, using GIMP or any other program, to change all shades of blue to their green equivalents? I guess technically it would be setting the G in the RGB to the value of the B. In case you're wondering, I'm trying to turn the planet Neptune green for a book illustration.

Thanks

Try Hue Saturation, selecting the primary color you want to change.

Try color-pick a blue, then swap the blue and green values over, to give a shade of green

Then maybe a new layer on top. fill with green, set the layer mode to color.

Much depends on your image.

all in one screenshot.

Three ways:

Add a layer, set it to "Hue" mode, and paint in green (you can also use any paint tool in "Hue" mode). But be careful or make selections to protect the non blue.

Colors>Map>Rotate colors. In the first wheel, set the range of blue hues to be changed, and in the second wheel, set the range of equivalent green hues.

Add layer mask, Color>Color to alpha and erase the source blue. Then add a layer under and fill with the required green.

More options:

"HSV Equalizer" in Rawtherapee maybe? There is no equivalent tool like this in GIMP or G'MIC unfortunately. The "Hue_Saturation" from GIMP rapidly causes color artifacts/errors.

In G'MIC you can use: "Customize CLUT" filter

G'MIC>Colors>Customize CLUT

Information about this "Customize CLUT" filter:
https://discuss.pixls.us/t/article-idea ... -clut/1681

Very helpful, thanks everyone.

from...



to...



(select planet, new transparent layer, fill area selected with yellow, multiply)