smu226:

bottleneck, made of these 2 nodes which I want as the output and force the NN to reconstruct the original image using these 2 numbers


Nowadays bottleneck is very abused term, what do you mean by bottleneck. For instance, inside some Resnet models there is a bottleneck part.

You should keep trying if you are using convolution networks, because convolution is a pattern matching.
Do you have the image you are actually searching inside the bigger image?