You should go with some node library for images, like >
js-imagediff
pixelmatch
node-opencv
Good starting point to explore more deeply about it >
https://stackoverflow.com/questions/4196453/simple-and-fast-method-to-compare-images-for-similarity
I tried to get base64data from image file but it didn't worked http://prntscr.com/s6966f most probably because it needs image id, how to get this image id ?