cary@Scripps.EDU (Steve Cary) (01/25/90)
In an attempt to not re-invent the wheel, does anyone have a readhexstring implementation that supports ascii run-length encoding??? The "natives" are getting restless about the ~2 hours required to download an 8-bit color postscript image to our QMS Colorscript 100 via a 9600 baud serial line... THANKS! -Steve Cary cary@scripps.edu Research Institute of Scripps Clinic, La Jolla, CA
amanda@mermaid.intercon.com (Amanda Walker) (02/08/90)
Here's some code that was posted a while back by Tomas G. Rokicki that does run-length encoding for black & white images. It will need some editing for use with the 'colorimage' operator, but it's the most efficient version of this kind of thing that I have seen yet: From: rokicki@polya.Stanford.EDU (Tomas G. Rokicki) Newsgroups: comp.lang.postscript Subject: Re: compressed images Message-ID: <10750@polya.Stanford.EDU> Date: 20 Jul 89 18:39:33 GMT > Has anyone implemented a PostScript run length decoder procedure that > will allow run length compressed files to be sent to the printer? > Assume that the compression is done by a C program in advance. Here's my entry. Comments have been added to the normal output of the program. % random definitions for width, height, etc. /W 378 def /H 230 def /BS 1 def /PW 0.99 def /ST 128 string def % a single-byte string for grabbing byte by byte /T 1 string def % n S - % This subroutine grabs the next `n' bytes from the stream and % returns them literally. Does it by grabbing a subinterval of % the appropriate length, and then readhexstring. /S { %def ST exch 0 exch getinterval currentfile exch readhexstring pop } bind def % n S - % This subroutine does a run-code; it grabs the next byte and % repeats it n-128 times. % First it grabs the next byte and stuffs it into all 128 % positions of the string. (This has been shown to be faster % than the `for' loop method.) It then grabs the appropriate % subinterval of that string. /R { %def 128 sub currentfile T readhexstring pop 0 get dup ST exch 0 exch put dup ST exch 1 exch put dup ST exch 2 exch put dup ST exch 3 exch put pop ST dup dup 4 exch 0 4 getinterval putinterval dup dup 8 exch 0 8 getinterval putinterval dup dup 16 exch 0 16 getinterval putinterval dup dup 32 exch 0 32 getinterval putinterval dup dup 64 exch 0 64 getinterval putinterval exch 0 exch getinterval } bind def % This is the general subroutine. We repeatedly get a byte, % compare it with 128, and call the appropriate routine. /G { %def currentfile T readhexstring pop 0 get dup 128 lt { S } { R } ifelse } bind def % Of course, image calls the above routine as many times as % appropriate. /DP { %def W H BS [W 0 0 H neg 0 H] { G } image grestore } bind def %%EndProlog gsave DP % And now, the data . . . AFFF01C091FF01EF9DFF01C091FF01E09DFF01C091FF02EF1F9CFF01C08CFF01BF84FF02EFE39C FF04C0E0F87F89FF017F84FF03EFFC3F9BFF04C0F2733F88FF01FE85FF03EFFFC79BFF04C0F332 3F88FF01FD85FF03EFFFF89BFF04C0F3303F88FF01FB85FF04EFFFFF0F9AFF04C0F3313F88FF01 .. Enjoy, -- Amanda Walker InterCon Systems Corporation "Many of the truths we cling to depend greatly upon our own point of view." --Obi-Wan Kenobi in "Return of the Jedi"
jef@well.sf.ca.us (Jef Poskanzer) (02/08/90)
So, is someone going to volunteer to do a frequently asked questions
posting for comp.lang.postscript? I'm not interested enough in
PostScript to do it.
---
Jef
Jef Poskanzer jef@well.sf.ca.us {ucbvax, apple, hplabs}!well!jef
"I am endeavoring, ma'am, to construct a mnemonic memory circuit, using
stone knives and bearskins."woody@rpp386.cactus.org (Woodrow Baker) (02/09/90)
In article <16032@well.sf.ca.us>, jef@well.sf.ca.us (Jef Poskanzer) writes: > So, is someone going to volunteer to do a frequently asked questions I am working on it. I am currently archieving all of the postscript newsgroup messages. I am also analyzing the questions asked, for frequency. Any input as to what questions to include the answers to will be much appreciated. Cheers Woody > > "I am endeavoring, ma'am, to construct a mnemonic memory circuit, using > stone knives and bearskins." ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ (SPOCK)