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Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.csd.uwm.edu!bionet!agate!ucbvax!mtxinu!sybase!alf!negris
From: negris@alf.sybase.com (Tim Negris)
Newsgroups: comp.sys.ibm.pc,comp.graphics
Subject: Re: .pcx files
Message-ID: <5902@sybase.sybase.com>
Date: 5 Sep 89 14:29:49 GMT
References: <5255@tank.uchicago.edu> <1492@ncrcce.StPaul.NCR.COM>
Sender: news@sybase.sybase.com
Reply-To: negris@alf.UUCP (Tim Negris)
Organization: Sybase, Inc.
Lines: 35

In article <1492@ncrcce.StPaul.NCR.COM> chuck@ncrcce.StPaul.NCR.COM (PUT YOUR NAME HERE) writes:
>In article <5255@tank.uchicago.edu> stel@tank.uchicago.edu (stelios  valavanis) writes:
>>does anybody know what files with extension .pcx are?  i'm fairly
>>certain they're some kind of graphics files but i don't have any
>>graphics prog to find out.
>>stel
>>-- 
>
>Graphics, Yup, that's for sure, but to add some more to your question:
>
>It seems that PC Paintbrush is the program that uses this as its standard,
>but I've seen PCX files that my PC Paintbrush can't load yet I can display them
>on my VGA monitor with other programs.  My question then is, are there programs
>that use the PCX extension to store graphics files in formats other than
>PC Paintbrushes?  If so, WHY?  And then there's the ubiquitous PIC extension that seems to plague me with the same problem.

It wouldn't surprise me if some program somewhere used the .PCX extension for file formats that PC Paintbrush won't load.  I think it is more likely that such programs are simply taking liberties with the info in the header in such a way as to make Paintbrush say, "Pass!"  The header contains slots that ZSoft documentation says things about like, "not used, should be 0".  If a program uses header slots in an incompatible way, it could cause a problem for Paintbrush and not for less discriminating programs.








Also, the Paintbrush header stores values to identify the type of graphics card in use, the number of colors and the dimensions of the screen for that card when the picture was saved, and the physical dimensions of the picture.  If a program stores a combination of values in those slots that do not make sense to Paintbrush or that it cannot accommodate in its present settings, it won't load the file.

Some things that would be considered unloadable:
-	unrecognized hardware manufacturer indicator
-	unsupported values for valid hardware (e.g. 320X200X16 EGA)
-	partial screen (it expects .PCC extension for that)
-	invalid picture or hardware dimensions for current card/setting

There may be others that are peculiar to the VGA, like invalid color palette specification, but that's just a guess.

Anyway, ZSoft in Atlanta will send you the header specification.  It used to be free, I think they may have started charging a nominal fee recently.

In the meantime, if you have a binary editor, e.g. Norton Utilities, PC Tools, etc.  you can examine the header (first 128 bytes) of an unloadable file and compare it with that of a genuine Paintbrush.  You may be able to edit it into a loadable condition.  I have done this many times.

As for .PIC, I have seen that extention applied to *many* different kinds of files that had absolutely nothing in common.