Just like to share this. You may probably know this…The theory behind why you should go with PhotoJPEG.
H.264 means Interframe compression. - Interframe means that the compression is dependent on other frames, so this mechanism uses keyframes which are saved as complete frames and then successive frames contain only the pixels that are different from the keyframe. This compression requires more processing power because the computer must process several frames at the same time in order to have a “complete picture” at any point in time. Examples include h.264, MPEG-4, DivX.
PhotoJPEG means Intraframe compression - Intraframe means that the compression is compressed individually and independently from the other frames. Basically each frame is “key”. As you guessed this is the less lossy compression. While it’s not as efficient in space saving, it more than makes up for in quality. Each frame is kept as an independent photo and this means very low detail loss, especially in clips with random motion (which are something that interframe codecs struggle with). Also this compression has much lower computing requirements. Examples include PhotoJPEG, MJPEG.
and I think, 4K meant to be large files. Otherwise How it can retain quality for such big resolution.
May be you can change PhotoJPEG quality upto 70-90%