Based on my understanding, the patent still needs to represent an "inventive step" from the prior art. Let's say you can show that
A. Classifying images based on a (pre-existing?) identification;
B. Filtering images based on classification;
C. Wirelessly transmitting images
were all known at the time. Then you could argue that a "person having ordinary skill in the art" would have known to combine A+B+C to solve the problem. Thus the prior art teaches the invention and the patent should be declared invalid.
This isn't wrong. But it's oversimplified and in practice in the US obviousness arguments have a low likelihood of success, lower if it gets too a jury trial.
You are much better off defending again infringement suits with novelty arguments.
A. Classifying images based on a (pre-existing?) identification; B. Filtering images based on classification; C. Wirelessly transmitting images
were all known at the time. Then you could argue that a "person having ordinary skill in the art" would have known to combine A+B+C to solve the problem. Thus the prior art teaches the invention and the patent should be declared invalid.