vary gray fill in a series

[rnmerchant]

I'm trying to produce a series of a simple image with a series of grey "intensities". I'm using the flood fill tool to change an area of grey to a different grey. This really means choosing from a spectrum - from white to black.

Often one sees this range reported in percents: eg 10%gray, etc. I don't see this option in color selection - on the properties/color/mono option the gray scale is measured from 0 to 255 (black to white).

Can anyone fix my terminology for me? Is this particular tool the best way to adjust this, or is there a better way?

The project is a for a laser engraver and I'd like to produce a series of images to compare how the laser manages it and which produces the best engraving. I could imagine the better way would be to use a vector image but that is beyond my skills and a simple PNG seemed like a good option.

Image attached. The staff/snake will be black, the maple leaf uncut completely, but the surround I would like to try at various intensities....

Appreciate the advice.

Richard

[Jean-Luc]

Try the Color Replacer Tool.
Select the grey of your image as the Background color.
Select the target grey as the Foreground color.
Paint with the Color Replacer Tool on your image.
It will replace the Background color with the Foreground color.