[Gimp-user] Fixing Deleted Left Behind Lines

[Drew Laborde <dlaborde gillis com>]

Dear Gimp,

I absolutely love the program I am just trying to figure something out. When I start a new project and I 
start editing the photo (i.e. drawing on it with the paintbrush) I encounter a problem when I try to select 
certain colors and delete. So lets say I have three colors in my image. I do a little drawing and editing on 
my image and then I want each separate color to be a separate layer. So I select two of the colors and delete 
them. Any things that isn't that third color or where the two colors I deleted used to be now has these 
"editing lines" is what I want to call them. You can see faint lines where I had made slight changes to the 
image with lets say the paintbrush. HOW DO I GET RID OF THOSE LINES? Some help would be much appreciated. 
Thanks.

Thomas