[A83] Re: ZPic83 compression

To: <assembly-83@lists.ticalc.org>
Subject: [A83] Re: ZPic83 compression
From: "Ronald Teune" <rtwolf@gmx.net>
Date: Wed, 12 Jun 2002 18:30:15 +0200
References: <5.1.0.14.2.20020610104230.009f9cc0@mail.bellsouth.net> <001301c21116$86df5090$021a450a@mindcooler> <004301c210d4$76d6e060$838d86cb@l3o6v0> <000901c2115b$98d77b70$021a450a@mindcooler>
Reply-To: assembly-83@lists.ticalc.org


> > Writing both is a good idea to check sizes.  but a vertical one would
also
> > be much larger..
>
> I don't see why thay would be..

Because the bytes are read left-to-right. If you do a bit-level vertical
compression, you'll have to read the 1st bit of the 1st byte, then the 1st
bit of the 13th byte, then the 1st bit of the 25th byte, etc.

> > I mean in the end that your 5 bits is compressed into 3, only saving 2.
I
> > was thinking of trying to merge the special byte and the run length byte
> > somehow but im pretty sure thats useless..
>
> Actually, my five bits is "compressed" into 8.
>
> > Only problem with this way is that, for random pictures (ones with no
> runs),
> > it would increase the size of thje picture
>
> That's right. PCX uses a kind of "special byte" (more than one), and it
> saves space
> compared to a simpler kind of RLE algorithm.
>
> /Jens
>
>

Follow-Ups:

[A83] Re: ZPic83 compression

From: =?iso-8859-1?Q?Jens_Bj=F6rnhager?= <jensbj@home.se>

[A83] Re: ZPic83 compression

From: Brandon Sterner <bms9019@rit.edu>

References:

[A83] Re: ZPic83 compression

From: Charlie Adams <charlieadams@bellsouth.net>

[A83] Re: ZPic83 compression

From: =?iso-8859-1?Q?Jens_Bj=F6rnhager?= <jensbj@home.se>

[A83] Re: ZPic83 compression

From: "Nat Allan" <nallan@hotkey.net.au>

[A83] Re: ZPic83 compression

From: =?iso-8859-1?Q?Jens_Bj=F6rnhager?= <jensbj@home.se>