Neat! But if we're sticking to the source code analogy, the matrix multiplier probably maps closer to a CPU or an interpreter - I wouldn't say every Java program is open source because you have an open-source JVM.
In all seriousness, compilation and model training are lossy processes and erase a lot of the context needed to understand the output (and with model training we don't fully understand it even with access to the training data). Images aren't necessarily derivative of anything, so the analogy breaks down here.
I would say that every image using a proprietary file format is proprietary. If the creator of such an image intends for the image to be otherwise free as in speech (any receiver can inspect, modify, redistribute with and without modification for any purpose), then the image can be made free if the image creator converts the image to a free format.