This is mostly a note to self. You know how you often have photographs of notes or forms that you need to print out, and there's a shadow or uneven lighting across the image which makes the print look bad?

These are the steps I take to make something like this friendlier for a black-and-white printer. I am using the amazing online editor Photopea, but most image editors can handle this.

Initial image adjustments

First, desaturate the image. Since we're going to print it out in b&w anyway, it doesn't matter. Bump up the contrast and brightness a bit too.

If the editor has a way to warp transformation or something similar, you can use it to straighten out the image a little bit.

Duplicating the layer

Now, duplicate the image layer. Invert the colours and apply a Gaussian blur (I used about 7 pixels as the blur value)

We can then change the layer mode from "normal" to "colour dodge"

Final adjustments

Then with some level adjustment, we can get the final output to look evenly lit and appropriate for printing.

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This is simply what worked for me, but there must be tons of other, better ways of doing this. Play around with the level adjustment, drop the bumping of brightness and contrast at the start, and you might get something that works best for the photographs of notes that you have.