Prediction with non-scalar output (label)
Neural Networks can have a vector or matrix as output layer, image segmentation is a well researched topic and deep learning (as most things concerning images) are the state-of-the-art. You will need (a lot of) training examples where the pattern is found, and where. This could be a bounding box, or per pixel if it is part of the pattern or not (this will generate a matrix equally sized to your input). To see if the pattern is found you could construct a second network that is just a binary classifier, or you could try to see if your pixel-based network will output almost only zeros in case of no pattern. In this case you will need negative examples as well.