OpenCV is compiled with libjpeg-turbo and all possible HW-flags for accelerated computing. At about 5 or 6 FPS the Raspberry Pi 4 uses about 100% of all 4 cores. The same goes for a non-threaded configuration. We manually set the framerate on the camera and monitor the number of threads spawned (which is about 3-4 concurrent threads at 5-6 FPS). We choose JPEG (even though its lossy) since PNG or TIFF compression takes longer to compute.