Poor man's document camera for videoconference
In these situations where you're taking a photograph of writing or a diagram on a piece of paper, it can be surprisingly tricky to get rid of the shading from the lighting conditions and be left with just the content on the page in high contrast.This explanation nails how to do it though: http://www.imagemagick.org/Usage/compose/#divideDivide a blurred copy by the original and you end up with effectively an adaptive-normalize filter where the result is nice and clear with the shadows and uneven lighting left behind.Also though, there are tools like https://miro.com and https://beta.plectica.com which kinda make this obsolete for many common use cases.