Recolor pixels between two colors/patterns

Question

I have a project where I have a design on a checkered background. To create this, I have a layer for the design and a layer for the checker. However, when I remove part of the design to show the background behind it, I get some light-colored pixels along the border that I do not want.

I would like to make these light-colored pixels black. I have achieved this before, somehow, with answers to this question, but I do not remember the steps I took and don't have my old project file.

The is an example of what I'm working with:

And how I would like it to look (except not hand-drawn and ugly, heh):

Any ideas?

Answer 1

Looks like you must have used the fuzzy select tool to make selections of white areas, then deleted them, leaving white pixels.

One possible fix:

1. Right click the design layer in the layers panel, and choose Alpha to selection

2. Make a new transparent layer above your design layer

3. Choose black as your foreground colour

4. Do Edit > Stroke selection, and use 2 or 3 pixels as the width

Answer 2

The real answer is to avoid this situation.

The proper way to remove the design is not to do a plain fuzzy-select + delete (or color-select + delete), When you do so, the pixels on your design that are on the white-to-black transition (and are various levels of gray) are either cut out or left in (and those left in make that white halo). And no, there is no proper threshold setting, if it is too high you get a pixellated/jagged edge, and if too low you get the white halo, and in the middle you get both.

The proper way is to do a color erasure:

• fuzzy select the part of the design you want to remove (white, I would guess)
• Select > Grow by a couple of pixels
• Set the bucket-fill to Color Erase mode

• Bucket fill the selection with the color you want to remove (white, I would guess)

When you do this, the pixels that are completely white are made totally transparent, and those on the white-to-black transition are replaced by black with various levels of opacity, that are composited cleanly with the pixels of the background layer and make a nice smooth edge.

See here for some more details.

PS: Come to think of it, you shouldn't even have to do this. The design should have been made on a transparent background (and possibly as several layers)...