I'm trying to come up with a method to match a given mathematical plot against a database of other plots. To make it more specific: plots are generated in R as PNG and might have different dimensions. The latter means that simple pixel-by-pixel matching won't work, even when resized, because text, plotting symbol, margins etc. between two versions of the same old are non-linear transformations of each other.
There's a number of good image matching algorithms available online but those assume any area in the picture is relevant, whereas with mathematical plots it's predominantly about the artifacts representing data that's being plotted.
I'm looking for pointers: is there an algorithm, paper etc. related to this task? Or maybe someone heard of a specialized DNN (which could help in identifying those most important artifacts)?
Appreciate any suggestions.