I'm looking to log some information on a piece of equipment I have running at home. It displays the information I want - operating rpm and some other settings - on seven-segment displays. In an ideal world, I'd like to log the value of this setting continuously, or at intervals.

The obvious thing to do would be to open it up and interface with the onboard electronics somehow, but I don't have much experience with this and am worried about breaking something.

A non-invasive solution a friend suggested was to use a camera to read the value off the screen. They figured if a camera were to be placed adjacent to the display and either recorded video or took pictures of the display periodically, these video/images could be automatically analysed for the values of the seven-segment displays and the results logged.

I have some experience with image analysis and reckon analysing brightness of certain pixels corresponding to active sections of the display relative to its background could be used to find the value from the display, as long as the camera/display were in a fixed position.

This idea sounds pretty good to me but based on some google research I can't find much information on similar schemes. Has anyone tried something similar, and have any pointers? Would something like this be possible? Is there a better way of implementing it?


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