1 | initial version |
cv::Matchtemplate could be a start. It slides a reference image over a image and compares them at each position.
2 | No.2 Revision |
cv::Matchtemplate could be a start. It slides a reference image over a image and compares them at each position. But it could be hard to get that in realtime (maybe after downscaling your desktop image or moving it to a GPU).
Next option would be feature based (Sift, Surf, ORB,...).
Do you have a perfect match? (e.g. are you looking for a specific icon?)