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Oswald
Registered: Apr 2002
Posts: 5027 |
koala otpimizing
Hi Everyone,
I know there's a c64 tool out there that helps with optimizing koala pictures for packing, but no idea what it is called. Anyone knows?:) Timanthes would do the job for me aswell with its nibble swapper tool, but is there a way to load/save a native c64 koala format picture with it ? *.prg doesnt works, what format does it expect to be .prg anyway ?:) |
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tlr
Registered: Sep 2003
Posts: 1724 |
It's here: Foris - Untitled
The others: Short Circuit & Song of the Sunset
I ripped the short circuit picture from the original game and the others from the releases. Available as prg's: test_corpus-20070401.zip
Bitmap: $2000-$3f3f
Screen: $3f40-$4327
Color: $4327-$470f
$d021: $4710
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WVL
Registered: Mar 2002
Posts: 886 |
Christopher : is your pixelshuffler the same kind like the brainfart i had to shift every 2nd byte by pixels to deinterleave? |
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ChristopherJam
Registered: Aug 2004
Posts: 1381 |
@tlr - Thanks for the pointers, and the c64 friendly corpus :)
@WVL - similar.
There are two levels of interleaving; the first takes each pair of bytes in the source and swaps the low nibble of the first with the high nibble of the second, so each byte then represents a 2x2 pixel block. The second shuffle places every second byte into a group of four, that hence represent a 2x8 pixel group (half char)
*rereads your comment*
"byte 0, byte 2, byte 1, byte 3, to try and undo the effect of pixelgrids."
Yup, that's pretty much my step two (though I take bytes 0,2,4,6,1,3,5,7), so a somewhat different effect given that I'm operating on already rearranged data. I was mostly attempting to increase the locality of the pixels, and experimented with a couple of different shuffles to see what combination made the most compressible image. Sadly, the first two pics both get slightly larger (around 30-40 bytes) if they are shuffled. |
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wil
Registered: Jan 2019
Posts: 46 |
Inspired by this thread, I made a tool that tries out different variants of rearranging the pixels in a Koala pic. In addition, it removes color information where less than 3 forground colors are used in a 8x8 area (or 8x4 if we count fat pixels) and sorts the colors accroding to a palette. All these features together help in compressing the Koala pic without changing the appearance.
The rearrranging requires a different display routine, since the bytes need to be unshuffled before displaying.
For packing I used exomizer.
All in all I got a filesize of 19045 byte including load address, decompression routine, unshuffling routine and display routine. I'm quite sure there is still plenty of room to optimze it.
The tool (it can be also used to optimize Koala pics without changing the format) and the packed example of the 3 file are here:
Pixelshuffler V0.4 |
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Zyron
Registered: Jan 2002
Posts: 2381 |
I normally use Pico v1.3. How good is that compared to the other options mentioned in this thread? |
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wil
Registered: Jan 2019
Posts: 46 |
Quote: I normally use Pico v1.3. How good is that compared to the other options mentioned in this thread?
I tried out Pico, it looks like a great tool, but what I understood is that you have to make some decisions to make it sorting? I only tried out the kill color function (CBM+K) which didn't give a good result yet. |
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soci
Registered: Sep 2003
Posts: 474 |
Compress all 3 together as I could easily get 18580 bytes without any tricks:
https://singularcrew.hu/temp/3koala-soci-singular.prg |
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wil
Registered: Jan 2019
Posts: 46 |
Quote: Compress all 3 together as I could easily get 18580 bytes without any tricks:
https://singularcrew.hu/temp/3koala-soci-singular.prg
Awesome! I saw that you had optimized Koalas in your solution - which program did you use for Koala cleaning/optimization? |
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soci
Registered: Sep 2003
Posts: 474 |
That must be a side effect as I was lazy to rip the pictures and converted from screenshots instead. |
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wil
Registered: Jan 2019
Posts: 46 |
Quote: That must be a side effect as I was lazy to rip the pictures and converted from screenshots instead.
A very positive side effect :-) - the resulting version is well suited for packing. What software or cartridge did you use to rip it? |
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