I need to grab selective parts of screenshots (24-bit RGB) and convert them on the fly to either 15-bit RGB (5-5-5) or 16-bit (5-6-5). I need to favor the least CPU intensive way to perform the conversion in order to introduce as little latency as possible. Context: screenshot will be taken at irregular intervals but often in rapid succession. I want to store them in an SQLite DB and keep the storage as small as possible. Some degradation in color accuracy is no problem. If needed I could