On Mon, Oct 08, 2007 at 08:52:19AM +0200, Tom St wrote: > What i would like to get, is the average color of each JPG-block (should > be in there) and if to many blocks change from frame to frame, i would > assume it is a motion. Do you have any hints for that?
Wikipedia has a good introduction on JPEG: http://en.wikipedia.org/wiki/Jpeg The average brightness of each 8x8 block is the DC coefficient of that block. If possible, you should try to work only with the brightness - in that case, you do not need to decode the colour information at all. The colour information is stored with a lower resolution - usually, the blocks are 16x16 pixels, but with my Logitech 9000 Pro, I suspect the resolution is even lower than that. > Currently i would assume i have to implement JPG decoding myself in order > to understand the algorithm and stop at the right decoding level. That's right! Cheers, Richard -- __ _ |_) /| Richard Atterer | GnuPG key: 888354F7 | \/¯| http://atterer.net | 08A9 7B7D 3D13 3EF2 3D25 D157 79E6 F6DC 8883 54F7 ¯ '` ¯ _______________________________________________ Linux-uvc-devel mailing list [email protected] https://lists.berlios.de/mailman/listinfo/linux-uvc-devel
