An approach is provided in which a knowledge manager processes an image using a convolutional neural network. The knowledge manager generates a pixel-level heat map of the image that includes multiple decision points corresponding to multiple pixels of the image. The knowledge manager analyzes the pixel-level heat map and detects sets of decision points that correspond to target objects. In turn, the knowledge manager marks regions of the heat map corresponding to the detected sets of per-pixel decision points, each of the regions indicating a location of the target objects.