If you could translate the JPEG images to something that is more X,Y,Value based (where the Value is some numerical number, grayscale values are ideal for this), it should be possible to identify "edges" which correspond to step-changes between adjacent "pixels". This is analaguous to "digital differentiation" - large deltas between 2 pixels, in the X or Y direction correspond to edges.

Without more info on the nature of the actual images, this might be a way of identifying images with a larger than normal edge count, without becoming embroiled in the neural network approach, and all that involves - training the network etc.

Pretty sure there must be some modules out there to convert from JPEG to "XYZ" formats, hopefully more knowledgeable monks out there could provide some direction there?