On 06/06/2012 21:36, Henri Sivonen wrote: > More to the point, the important characteristic is being able to stop > downloading *quarter* way through the file and get results that are as > good as if the full-size file had been down sampled with both > dimensions halved and that size had been sent as the full file. (I am > not aware of a bitmap format suitable for photographs that has this > characteristic. I am aware that JPEG 2000 does not have this > characteristic. I believe interlaced PNGs have that characteristic, > but they aren't suitable for photographs, due to the lossless > compression.) IIRC Kodak's PhotoCD image format had this characteristic. The first part is a low res. image, the second is the differences between the low res. image zoomed to the high res. size and the actual high res. image.
Regards -Mark