caffe extract features - tool batch size and model batch size

https://github.com/BVLC/caffe/issues/585#issuecomment-51856173
Caffe operates on batches of data in GPU mode to reduce the overhead of communicating between the host and device. The feature extraction example batch_size is set to 50, and when the tool is called it is given 10 iterations as its argument, so it is actually processing 500 inputs. Set the batch_size and iteration arg to both be 1 to process a single image, although that's less efficient in throughput.

batch_size is set to 50
the tool batch size is set to 10 then it will extract 500 image features
the tool batch size is set to 20 then it will extract 1000 image features