Use GIMP to replace very faded colors in scan with bolder colors

Question

I'm definitely not an advanced user! On our wall is a beloved old crayon Valentines poster. After years, the red and orange colors have really faded so half the image is unreadable.

So, I made a color, high resolution scan of the poster's parts and reconstructed them in a quite large GIMP document.

You can see in my screenshot, the red and orange parts of the drawing are very, very faded and not readable.

Can you give me just basic guidance on which GIMP features would allow me to "sniff out" those very light crayon marks, and have the app replace those pixels with bolder color?

• Perhaps it is some "color replacement" feature, but then I wonder... If I grabbed one of the faded colors, how would I do that, and how could I get it to recognize the adjacent colors, since those faded color bits naturally have a slight shading of closely related colors in them...

• OR perhaps it's some kind of magic wand method that sniffs that there is some marked zone there and it captures all of the marked areas, and then I would change all the captured pixels to be a bright red. (sure would be nice if the colors I replaced with could have some variation though instead of one uniform color.

If you could point me on my way, I would be truly grateful! Thanks... here is the screenshot:

Answer 1

If you don't mind a bit of manual work, then this is feasible

1. Select a soft edged brush, about the size of the small circles inside the flowers. Set the Paintbrush blend mode to "Overlay"

2. Choose a pinkish-red colour, paint over the red crayon

3. Choose a yellow colour, paint over the yellow crayon

4. Choose white, paint over the shadows of the paper to remove them.

Before and after

5. Do a Levels adjustment, and drag the middle pointer (shown highlighted in red) to the right a little. This will strengthen the contrast, and make the colours pop a little more.