Macintosh Compression for Document Images

Macintosh Image Compression Specifications

Image compression formats supported:

CCITT Group 4, Group 3 1-D, TIFF Group 3 Mode 2 (a variation of Group 3 1-D).

Concurrent rotation and/or scaling to a balanced black & white density can be called concurrent with decompression. Optionally, scale to grey can be called after decompression.

Performance:

Acordex offers the only compression, decompression, scaling and rotation optimized for the PowerPC computer chip. It is written in IBM Power Assembler, making this useful on any PowerPC operating system, including Macintosh (including System X), AIX, Linux. The tight execution loops are optimized to fit into the on-chip cache. This takes maximum advantage of the RISC pipelining capability to provide faster performance than any other desktop imaging solution on the market.

Code Sizes

These routines are shipped as linkable modules. They have been compiled in the MPW environment and the Code Warrior environment. Linking them into your program will add the following:
680X0: 66 KB
PowerPC: 14 KB

Subroutine call structure

; decompress image:
; Called from 'C' as  follows:
;	dcimage(char *bitmap, char *compdata, int width, int depth, int rotation, int scalefact, int type)
; where:
;	bitmap = ptr to buffer to place uncompressed image
;	compdata = ptr to buffer with compressed data
;	width = width of image in pixels
;	depth = depth of image in line
;	rotation = angle to rotate data / 90 degrees (0,1,2, or 3) + 4 if scaling
;	scalefactor = 16 bit fractional scale factor (< 1)
;	type = Compression Type (0 = Group 3, 1 = Group 4)
;
;
; compress image:
; called from 'C' as follows:
;	cpimage(char *bitmap, char *output, int width, int rowbytes, int depth, int type);
; where:
;	bitmap = ptr to buffer containing uncompressed image
;	compdata = ptr to buffer to store compressed data
;	width = width of image in pixels
;	rowbytes = number of bytes per row (can be odd or rounded up even)
;	depth = depth of image in lines
;	type = Compression Type (0 = Group 3, 1 = Group 4)