[A83] Re: ZPic83 compression


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[A83] Re: ZPic83 compression




maybe he means the bytes in the 8 pixel wide columns, not the columns of
pixels.  So he'd think of byte 0 being next to byte 12, next to byte 24 in
plotsscreen.  And 1 next to 13 next to 25.  Just a thought and this is
thinking in the standard display method. You could easily change how the lcd
reads the bytes by converting to column mode rather than row mode which the
calc is usually set in.  Sorry if I missed something and this was already
said, I kinda jumped in the middle and didn't go look at the archives yet.

Brandon
----- Original Message -----
From: "Ronald Teune" <rtwolf@gmx.net>
To: <assembly-83@lists.ticalc.org>
Sent: Wednesday, June 12, 2002 12:30 PM
Subject: [A83] Re: ZPic83 compression


>
> > > 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
> >
> >
>
>
>
>




References: