Decompress pictures

[TXG/MNX]

Hello,

 

What would be the best option to use to decompress a serie of pictures in sequence

 

ice, lzjag, bpeg, arj ? I am interested to know which packer would be optimal for this.

 

 

[ggn]

If you're not going to share more info then I would suggest you trying every packer out there and compare sizes. Different packers yield different results depending on what's required of them.

[Zerosquare]

Depends on the kind of picture.

 

For photos/complex graphics, and if you can tolerate some quality loss, BPEG will give much better compression ratios than others formats.

You can also try Ray's BIQ stuff (at the end of the page):

http://web.archive.org/web/20070206115827/http://freenet-homepage.de/ray.tscc/misc.htm

 

For simple graphics or if you need perfect quality, try ICE, LZ, ARJ, etc. and see which one works best with your pictures.

[TXG/MNX]

Hi,

 

Didn't know this BIQ stuff only the jaguar supports not there:

 

at present BIQ supports 8bpp greyscale, 8bpp colormapped (!) and 24bpp RGB images.support for 16bpp RGB / 16bpp CrY (jaguar) is planned for the future.

 

But compression ration seems pretty good.

 

I mainly use 256 color BMP files size 320x200 and 160x200 I want to decompress them as quick as possible so within 1 frame when possible.

[Zerosquare]

Then BPEG isn't suitable.

 

Try the different lossless compressors and see which one is the fastest.

[Chilly Willy]

You might consider ELM's Tiny JPEG: http://elm-chan.org/fsw/tjpgd/00index.html

 

It can decompress to RGB565, so it shouldn't be too hard to rewrite for other 16 bit modes.

[Zerosquare]

I doubt it would be fast enough to decompress in one frame time, when BPEG which is optimized for the GPU can't do that IIRC.

[Chilly Willy]

He's not going to get ANYTHING for images with decent compression that will decode in one frame... that's the realm of video compressors where they compress over several/many frames to get the compression while being roughly fast enough to decode in one frame. If he wants that, he should be looking at cinepak, not any single image compression scheme.

[+CyranoJ]

I'd say the only way you'd do that inside of a frame is with deltas. That's just too much data to process in 1/60th of a second.

[Songbird]

I used LBM / IFF (also known as Deluxe Paint format) for compressed 256-color graphics in Protector, but even relatively small graphics took more than 1 frame to decompress.

 

320x200 is 64KB uncompressed with 8 bits per pixel. What's your target medium (cart vs. CD), and how many frames do you need?

[GT Turbo]

This is RLE compressed, you can use the same routine than Degas Elite PC1 format.

 

I think you can add some lines for 8 bitplanes, here come one routine i coded some years ago :

 

http://www.atari-wiki.com/?title=Fast_Degas_PC1_decompressor_code

[ggn]

For quick depack times lz77 is probably the best solution. Although packing ratio might not be satisfactory.

[Chilly Willy]

For quick depack times lz77 is probably the best solution. Although packing ratio might not be satisfactory.

Yeah, I use lz77 when I can. It's good on some things, but not really great on most images. Compressing is a bit slow, but decompressing is really fast.

[TXG/MNX]

I decided to start with ice packer, thats also used in Native from Duranik and seems pretty quick, there is dsp version and source. I did see that the pictures from that game were very small in compression so that would fit my need I guess but I will do more tests in the future to see if I stay with ice or switch.

[GT Turbo]

If you want a lz77 dsp unpacking rout for the Jag, just ask

 

http://www.jagware.org/index.php?showtopic=98&pid=4627&mode=threaded&start=&do=findComment&comment=4627

 

GT

[TXG/MNX]

That was an old thread :-) I see I visited this aswell someway I lost it. Thanx, there was also a talk about lz78 I remember is that an even better decompressor ?

 

There are many formats so I get a little confused by lz77, lz78 etc.. It seems to me both can get the same packing ratio only the way it works is different.

 

I did read about lz4, it should not compress aswell as lz77 but would be very fast (how much would the packing ratio be compared to lz77) ? Is there an lz4 decoder for the dsp ? Or @GT Turbo could you write one ...

[GT Turbo]

Hi Txg

 

everything is possible, just finding free time

 

See which unpacking rout you need and send a message We will see what we can do for you

[TXG/MNX]

Ok let you know for now its ice i am not a good coder yet learning goes slow reading books docs and look in examples to see how things work but i get there by myself :-)

[GT Turbo]

I have started with Gfa basic, and after i started to learn asm, it was very difficult at the beginning, but when you got some knowledges with this langage, it's a powerful langage, giving speed and technics

 

If you have questions, just ask, there are a lot of experimented coders in 68000 here