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picture compression algo help

Read or post about compression. And decompression. Or ask questions how to decompress your files.
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peter2005
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picture compression algo help

Post by peter2005 » Fri Mar 25, 2016 10:03 am

Hi, does anybody have any idea what this compression can be?

What I found:
- lossless image compression
- word at offset 8 is x resolution
- word at offset 10 is y resolution
- packed data starts at 0x18

In the attachment are 3 files, packed , unpacked and bmp of a small black picture.

thank you in advance

http://www75.zippyshare.com/v/7xv1pMrV/file.html

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shakotay2
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Re: picture compression algo help

Post by shakotay2 » Fri Mar 25, 2016 12:32 pm

reminds me of pcx:

0x0080 F0 03 F0 01 F0 03 F0 03 F0 01 F0 03 F0 03 F0 01 ð.ð.ð.ð.ð.ð.ð.ð.

How did you create that black.packed file?
Bigchillghost, Reverse Engineering a Game Model: viewtopic.php?f=29&t=17889
extracting simple models: viewtopic.php?f=29&t=10894
Make_H2O-ForzaHor3-jm9.zip
"You quoted the whole thing, what a mess."

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peter2005
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Re: picture compression algo help

Post by peter2005 » Fri Mar 25, 2016 1:03 pm

I did not create black.packed it's as I got it.

There is no problem converting unpacked version to bitmap, that's what I did, compression is the problem.

I tought of RLE at first, but it does not seem to be.... :roll:

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Re: picture compression algo help

Post by Apollo » Tue Mar 29, 2016 11:01 am

Hmm, where is this used? some game art?
Did they not supply an encoder as I gather your intent is to understand it and create own encoder than try decode them since got tool for it already.

If you have additional compressed files to compare than just this one with blank data could confirm more the layout.

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Re: picture compression algo help

Post by peter2005 » Thu Mar 31, 2016 8:24 pm

yes, it's a game art

You are right, there is no public encoder, but I hope it's some sort of known compression.

Nonblank example file here:

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Re: picture compression algo help

Post by Apollo » Fri Apr 01, 2016 5:10 pm

Looks like custom RLE method with similarities to PCX yet not entirely, else holds 24 bit color data between rle packets.

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