Comment abandon standard format numbers (Score 1) 135
Much of their compression comes from they dont use full 32 bit floats or integers to store the discrete cosine transform coefficients, but variable bit length numbers which can be squished more tightly. I didnt read the paper deep enough to study how efficient this bit hacking is machine operations. There might be few clever tricks there.
Bit hacking was more common in the early days of computers when core memory was very expensive. I recall Woz had some clever way of compressing color and shape graphics in the Apple II.