The invert function is commonly used to convert a scanned film negative into a positive but clever and artistic people can use it in many other ways too. Photoshop is a very powerful program. Compared with the features in the software, I barely know how to use even the most basic functions.
It is the most commonly used program used with scientific imaging, mainly because it is easy to layer different images and some of the basic math functions. It is commonly used in microscopy to overlay images containing different information. For example, a bright-field image (the kind we are most familiar with) shows the shape of a cell, a researcher can overlay the fluorescent image of the same cell showing where a dye has bound to actin to explain why the cell has that shape. I've used it myself for a recent paper to enhance a spot on a thin layer chromatography plate, and included the unretouched images with the supplementary results. Photoshop is also used to find possible data manipulation and poorly represented data: https://pubs.acs.org …0.1021/acscentsci.0c01049
Back when I was doing my Electronics Engineering degree back in the mid 90's we had a Biologist teaching the C Programming for Engineers courses. Most of the practical assignments involved writing various image processing filters, various interpolation methods, edge finders that sort of thing. His research field was machine vision, for spotting the division of the nucleus in plant cells. This was in like 93/94. That's where I also got to "meet" Lena Sjööblom for the first time. Thanks to the top half of her November 72 Playboy centerfold becoming a "standard test image". Actually as long as you know the mathematical algorithm for a filter the implementation is not too hard. At least if you are working in monochrome. Colour you have to do three times, and look out if you have to cross the colour channels.
Alan
