Start with your base, sharpen or whatever you want to do for your base.
Duplicate the base and set to 100% overlay.
Make a new fill layer of a dark blue, I used #00144D. Set it to exclusion 70%.
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Using #C20000, click on the fill/adjustment layer icon at the bottom of the layers window, the one that looks like a circle that's half white, half black. Then click on "gradient" in the list that comes up.
^That's what I set mine to, but you can play around to whatever suits your icon.
Duplicate the layer once, and set both layers to lighten. And you get something like this:
Using this by
ianthinae set to soft light at 30%.
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Use this and set to screen 100%, move around until you have it somewhere that looks good.
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Use this by
ianthinae and set to soft light 100%. I erased some parts that were covering her face.
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The icon looks pretty good now, but I wanted it a little less yellow so I did one last step.
Duplicate your base, bring to the top, desaturate and set it to soft light 100%.
And that is that. Any questions, please ask :]