Part of the point of this compression algorithm is for the designer to alter the image so that it can be better compressed. So the amount of compression really

Part of the point of this compression algorithm is for the designer to alter the image so that it can be better compressed. So the amount of compression really depends on how much the designer is willing to compromise their vision. I would guess that the average amount of compression might be better than 4:1. (That is less than a quarter of the uncompressed size)