Converting a color to alpha
I just figured this out and want to write it down while it is still fresh.
In GIMP you can convert a color to an alpha channel, making everything in the image transparent by the amount of that color that it contains. However, by simply making everything semi-transparent you loose some of the brightness of the original image.
To get around that, create a new layer mask for the layer with the new transparency. In the settings select "Layer's Alpha Channel". Then select the new mask, ctrl-a to select all, then copy. Create a new layer and paste the mask data into it. Make sure you click the anchor button in the layers windows.
Invert the new layer and set it's mode to "Dodge". This will cause it to lighten layers below it but only where it is white, or the areas that became transparent.
I am using this technique to add transparency to the rings of Saturn. It seems to be working pretty good so far.
Then again, I haven't even saved the file in GIMP. We shall see.
UPDATE:
This has worked VERY well!! I used this technique to create a texture map for the rings of Saturn. When I would add transparency the texture became transparent AND dark where it needed only transparency. It has worked so well that I forgot I had done this. Huge success.
Here is the texture in action. This is a computer generated image of Saturn created using Blender.
In GIMP you can convert a color to an alpha channel, making everything in the image transparent by the amount of that color that it contains. However, by simply making everything semi-transparent you loose some of the brightness of the original image.
To get around that, create a new layer mask for the layer with the new transparency. In the settings select "Layer's Alpha Channel". Then select the new mask, ctrl-a to select all, then copy. Create a new layer and paste the mask data into it. Make sure you click the anchor button in the layers windows.
Invert the new layer and set it's mode to "Dodge". This will cause it to lighten layers below it but only where it is white, or the areas that became transparent.
I am using this technique to add transparency to the rings of Saturn. It seems to be working pretty good so far.
Then again, I haven't even saved the file in GIMP. We shall see.
UPDATE:
This has worked VERY well!! I used this technique to create a texture map for the rings of Saturn. When I would add transparency the texture became transparent AND dark where it needed only transparency. It has worked so well that I forgot I had done this. Huge success.
Here is the texture in action. This is a computer generated image of Saturn created using Blender.
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