techniques available for image recognition in screenshots

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I need to analyze screenshots for patterns, like searching for a known image, or text, so far template matching seems to be the most straight forward and applicable, would like to know what other options exist, and if possible a block diagram/sequence of steps, e.g. segmentation, dilation, erosion, blob detection.

I've been reading through scattered references and am at a lost on what key techniques are relevant to achieve my purpose, so any pointers in applicable bibliography also welcome. Thank you.