- Make a selection on the character (or anything you want to protect)
- Select>Save to channel: this saves the selection mask as a channel (see channel list)
- When you make a color selection, go to the Channels list, right click on the saved selection, and Subtract from selection: now you selection is whatever you selected minus anything in the character.
Note that the selection can be restricted to the sensitive parts: eyes and dress.
If you use ofn-tiles to work on a tiled image, you can
- Select>Save to channel: this saves the selection mask as a channel (see channel list)
- When you make a color selection, go to the Channels list, right click on the saved selection, and Subtract from selection: now you selection is whatever you selected minus anything in the character.
Note that the selection can be restricted to the sensitive parts: eyes and dress.
If you use ofn-tiles to work on a tiled image, you can
- create the selection on a single frame in a distinct image (that image should be the size of a tile in the tiled image, and framed the same way).
- Select>Save to channel
- Make the channel the active "drawable" (click on it in the channels list)
- Select>All, Edit>Copy
- Open the "tiled" image
- In the Toolbox or the Patterns list, select the "Clipboard" pattern
- Layer>New layer, and select the Pattern fill (you can also create a blank layer, and then use the bucket-fill in "Pattern" mode). In both cases you should end with the mask created in the frame image replicated over each tile.
- Open the Channels list
- Drag any of the R,G,B channels (they are all identical anyway) to the list below to make a copy, and optionally rename the copy.
- You can now use that channel as a subtraction mask as above