So far I've found topics which describe how to compare to images by its preferences (saturation, blur,...) to see if they are identical.
However, what algorithm can help me to detect is an image (taken by a photo camera, mobile camera, etc.) contains a circle for example or a square?
In the database, I will have a list of objects (circle, square, polygons,...) and the algorithm should compare if any of these objects is present on a photo.