Example of Levels High Input setting


The same effect being mimicked using Gimp layers


This thread is a short guide on how to mimic Levels settings and invert using Gimp blend modes. Please remember that all of these are shown on very high values and that lowering a layers opacity or making a grayscale color fill can make the effect much less intense, and to optionally put the color fills inside a pass through layer group. You can also set a keyboard shortcut to auto fill the canvas with the primary color like I do. The instructions are below.

1. A Grain Merge black fill on Blend Space RGB Linear is similar to Low Input or gegl:levels in-low

2. A double stacked Overlay on a white fill is similar to High Input or gegl:levels in-high

3. Normal on a white fill is similar to Low Output or gegl:levels out-low

4.Normal on a black fill is similar to High Output or gegl:levels out-high

I cannot recreate the invert effect that out-low and out-high do together or the partial invert effect that in-low and in-high do together. But a white color fill on the difference blend mode can invert and making it a grayscale color fill can partially invert an image. In my Gimp I have a custom keyboard shortcut that 'auto fills' a layer with the primary color to make this workflow easier. I hope this helps Gimp's community edit more professionally.