So, we looked at JPEG image encoding, which is a very popular image codec. Especially since our image is going to be blurred heavily on the client, and thus band-limiting our image data, JPEG should compress this image quite efficiently for our purposes. Unfortunately, the standard JPEG header is hundreds of bytes in size. In fact, the JPEG header alone is several times bigger than our entire 200-byte budget. However, excluding the JPEG header, the encoded data payload itself was approaching our 200 bytes. We just needed to figure out what to do about that pesky header!
The technology behind preview photos