[Coco] Compressed pictures

[coco at yourdvd.net]

I think they were by someone else, but I'm sure they were based on what
you and Mike Ward had accomplished.

> -------- Original Message --------
> Subject: Re: [Coco] Compressed pictures
> From: Arthur Flexser <flexser at fiu.edu>
> Date: Sun, April 29, 2007 2:17 pm
> To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
> 
> PIXFILES.BAS and MAXFILES don't ring a bell.  What are those?
> 
> Art
> 
> 
> On Sun, 29 Apr 2007 coco at yourdvd.net wrote:
> 
> > Art, I have located PIXCMP.BAS. I am still looking for MAXCMP.BAS. Have
> > also found PIXFILES.BAS. If I find MAXFILES, do you want me to send
> > them to you? Blast from the past man - rob
> > 
> > > -------- Original Message --------
> > > Subject: Re: [Coco] Compressed pictures
> > > From: Arthur Flexser <flexser at fiu.edu>
> > > Date: Sat, April 28, 2007 10:59 pm
> > > To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
> > > 
> > > I'm not sure about the Delphi and Compuserve archives.  I recall
> > > somebody on
> > > this list archived the Delphi CoCo SIG MESSAGE base on a CD, but I'm
> > > not sure
> > > about whether anybody has archives of the data libraries.  Come to
> > > think of it,
> > > what does SIG stand for, again?  <something or other> Interest Group,
> > > I think.  
> > > A term I haven't heard in a long time.  Special Interest Group? 
> Subject
> > > Interest Group?  Was this term used in places other than Delphi and
> > > Compuserve?
> > > 
> > > MAXCMP.BAS was descended from the earlier PIXCMP.BAS, and added the
> > > capability
> > > of compressing double-screen CoCo Max pictures as well as PMODE 3
> single
> > > screens, allowing scrolling of the double-screen ones by the arrow
> > > keys.  The
> > > point of having the graphics converted to printable ascii characters
> > > was to
> > > allow the transmission of graphics as text files, in the days
> before CoCo
> > > terminal programs were routinely capable of transmitting binary
> files,
> > > and when
> > > BBSes often restricted uploads to text files.  This "asciifying" step
> > > increased
> > > the size of the compressed graphics by a factor of 8/6 (1.33), since
> > > only the
> > > lower 6 bits of each ascii character could be used for
> representing the
> > > graphics.  The Compuserve and Delphi program data libraries had a
> > > large number
> > > of graphics files encoded using PIXCMP and MAXCMP.
> > > 
> > > Art
> > > 
> > > On Sat, 28 Apr 2007 coco at yourdvd.net wrote:
> > > 
> > > > Hello Arthur: I have wondered recently if there existed archives
> of the
> > > > Delphi and CompuServe CoCo SIG's from back in the day. Are they
> online
> > > > somewhere (perhaps at delphi or compuserve themselves? I suppose I
> > > > could do some searching)... Thanks - Robert
> > > > P.S. I remember the program of which you speak, the one you
> wrote. I
> > > > think it was the one I used to transmit graphics screens as ascii
> > > > rather than binary many moons ago.. r
> > > > 
> > > > > -------- Original Message --------
> > > > > Subject: Re: [Coco] Compressed pictures
> > > > > From: Arthur Flexser <flexser at fiu.edu>
> > > > > Date: Sat, April 28, 2007 4:05 pm
> > > > > To: CoCoList for Color Computer Enthusiasts
> <coco at maltedmedia.com>
> > > > > 
> > > > > It is unclear why you would find LOADMing a 6K screen "too
> much";  it
> > > > > shouldn't
> > > > > take much time to load, and the fact that it is 3 times longer
> than
> > > > > the main
> > > > > program seems to me not particularly relevant.  If you want to
> > > > > compress the
> > > > > picture, a decent algorithm is to use byte, rather than bit,
> > > > > repetitions and
> > > > > think of the screen as a series of 8-bit wide byte columns. 
> The same
> > > > > byte
> > > > > repeats very frequently in vertically adjacent positions in a
> typical
> > > > > graphics
> > > > > screen.  A program I co-wrote years ago, MAXCMP.BAS, uses this
> and
> > > may
> > > > > be online
> > > > > somewhere in a CoCo archive. (That one took the additional
> step of
> > > > > converting
> > > > > the resulting screen to printable ASCII bytes and embedding the
> > > resulting
> > > > > encoding into a generated BASIC program that when run
> displayed the
> > > > > picture.  
> > > > > It was listed and written up in some issue of Rainbow, in one of
> > > Marty
> > > > > Goodman's
> > > > > columns.  It should also be in the Delphi archives, along with a
> > > detailed
> > > > > description of its compression algorithm.)
> > > > > 
> > > > > Art
> > > > > 
> > > > > On Sat, 28 Apr 2007, Diego wrote:
> > > > > 
> > > > > > While writing some of my BASIC programs, I thought about adding
> > > a intro
> > > > > > screen. The options were add the drawing commands to the
> program
> > > (slow,
> > > > > > limited) or load a graphic screen. But even a PMODE 3 screen is
> > > 6Kb,
> > > > > a bit
> > > > > > to much for a 2 Kb program So I came up with a very simple
> > > compression
> > > > > > rutine. 2 bit for color, 6 bits for how many pixels of that
> > > color. Some
> > > > > > sample simple screens came down to just under 1 Kb (I know that
> > > some
> > > > > complex
> > > > > > screens can become a lot larger than the original) My
> question: Is
> > > > > there
> > > > > > some format/way to get a screen picture+loader in less than
> 2 Kb
> > > thatls
> > > > > > already out there somewhere?
> > > > > > 
> > > > > > Diego
> > > > > > 
> > > > > > 
> > > > > > -- Coco mailing list Coco at maltedmedia.com
> > > > > > http://five.pairlist.net/mailman/listinfo/coco
> > > > > > 
> > > > > 
> > > > > 
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