dan@sics.se (Dan Sahlin) (07/15/90)
bruce@archive.rtp.dg.com (Bruce Kahn) writes: > You can FTP the specs from apple.com [130.43.2.2] from the /pub/dts/mac >directory (or wherever it is under /pub). I looked at the files, and there are just some test PICS which you can try your software on and no documentation. In Inside Macintosh, there are descriptions of the formats, but I have yet failed to find any description on how the 32-bit and 16-bit color pictures are compressed. All I know that some kind of run-length code is used. As the software for compressing and decompressing the pictures are included in the 32-bit Mac software, this is not a problem on a Mac. But keeping the compression algorithms secret makes it impossible to unpack the on anything but a Mac. I wonder if it is intentional from Apple to keep the compression as a trade secret, or that they simply cannot imagine anyone trying to create and read PICS on anything but a Mac? /Dan Sahlin email: dan@sics.se PS. Does anyone have any ideas how the dithering is performed in 32-bit Color Quickdraw? It seems to work very well, and I can display a dithered version of color pictures even on a black and white Mac SE/30. Unfortunately this feature is for some reason disabled on a Mac Plus.
jackiw@cs.swarthmore.edu (Nick Jackiw) (07/17/90)
dan@sics.se (Dan Sahlin) writes: > In Inside Macintosh, there are descriptions of the formats, but I have yet > failed to find any description on how the 32-bit and 16-bit color pictures > are compressed. All I know that some kind of run-length code is used. > But keeping the compression algorithms secret makes it impossible to unpack > the on anything but a Mac. If you refer to PICT2's compressed bit-image operators, the image data is encoded by the Mac Toolbox's PackBits() routine (and decoded by UnpackBits). These routines manipulate a format which is documented in the Macintosh Tech Notes (#171, if memory serves). These too are available from apple.com. > PS. Does anyone have any ideas how the dithering is performed in 32-bit > Color Quickdraw? It seems to work very well, and I can display a dithered > version of color pictures even on a black and white Mac SE/30. > Unfortunately this feature is for some reason disabled on a Mac Plus. Color QuickDraw, and its 32-bit superset, are written in 68030 code. The Mac plus is a 68000. The feature is not disabled; it is nonexistent. -- -----Nicholas Jackiw [jackiw@cs.swarthmore.edu|jackiw@swarthmr.bitnet]----- "... Then, with an infernal shovel that increases my strength, I dig out of that inexhaustable mine whole chunks of lice, big as mountains. I split them up with an axe and I transport them in the depths of night to city streets."