paint mode - color erase mode - Printable Version

paint mode - color erase mode - Printable Version

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paint mode - color erase mode - gimp-artist - 05-19-2018

[attachment=1735]
I'm testing "color erase" mode for paint tool. Background color is cyan. I painted blue color on it in the "color erase" mode. Then the green color came out. It is fine.

Now background color is yellow. I painted red color on it in the "color erase" mode. I'm expecting green color for the result, but nothing happens. What's wrong with this approach?

RE: paint mode - color erase mode - rich2005 - 05-19-2018

Quote:...What's wrong with this approach?

Just about everything, but we make allowances for overzealous beginners here Wink

First is your colour chart (plucked from the internet ?). That shows a 'picture' of RGB additive interaction between the primary colours. Use Gimp. Make your own.

[Image: oDegUCC.jpg]

Note it has a black background, white has a value (rgb 255,255,255) so use black (0,0,0). The red and green (blue as well if you want) layers are in additive mode. That gives the correct addition of the primary colours.

Paint brush in colour erase mode.
This does what it says, it erases a colour providing you have an alpha channel. It does not do anything else. Useful if you have a solid colour background, you can paint it out and retain the same colour in other parts of the image. (which is not possible with say, color-to-alpha)

[Image: zip0s66.jpg]

Quote:Now background color is yellow. I painted red color on it in the "color erase" mode. I'm expecting green color for the result, but nothing happens.

Wrong mode. Remember the bit about RGB being an additive process. It is now the reverse, paint in Subtract mode. red over yellow to give green.

[Image: we7KJyb.jpg]

You really do need to start experimenting with Gimp. You will learn much along the way and no matter how long you use Gimp there is always something new to learn.

RE: paint mode - color erase mode - gimp-artist - 05-19-2018

Thanks for the detailed reply.

This gimp-forum.net is helping me a lot. I appreciate it. Someday I hope I might reply for the newbies.