04-02-2017, 03:20 AM
(This post was last modified: 04-02-2017, 03:25 AM by Bomb Bloke.)
A few weeks ago I wrote an ETC1 decoder, using this specification. The format is a lossy one which doesn't actually support transparency, as such - attempts to make it do so are often designed to be compatible with decoders that won't recognise them (so that you'll always get an otherwise correct representation of the image back, even if the output lacks alpha). Because of this, generic decoders which do support those methods have to likewise guess if they're in use (or be told), because there aren't any specific flags to indicate that they're there...
Editing the files manually via a hex editor may be tricky, as encoded images are divided into chunks which are each represented by multi-byte records. Significant changes targeted at even single pixels within these chunks may likewise require significant changes to their records, which is 1) tricky to figure out in your head and 2) may force you to degrade the quality of the pixels surrounding the ones you want to change.
I'm afraid I can't quickly provide you with sample files directly from my end. There are a small handful of ETC1 texture images in King of Fighters-A 2012's OBMs (eg mstage_bigben_1.obm, buried within its OBB and extractable with this), and Metal Slug Revolution has tons of them within its Unity CABs.
If you really get stuck then I think it might be interesting to write some software for your particular files, but I'd need to get some samples of the encoded originals so's I can code around their headers.
Editing the files manually via a hex editor may be tricky, as encoded images are divided into chunks which are each represented by multi-byte records. Significant changes targeted at even single pixels within these chunks may likewise require significant changes to their records, which is 1) tricky to figure out in your head and 2) may force you to degrade the quality of the pixels surrounding the ones you want to change.
I'm afraid I can't quickly provide you with sample files directly from my end. There are a small handful of ETC1 texture images in King of Fighters-A 2012's OBMs (eg mstage_bigben_1.obm, buried within its OBB and extractable with this), and Metal Slug Revolution has tons of them within its Unity CABs.
If you really get stuck then I think it might be interesting to write some software for your particular files, but I'd need to get some samples of the encoded originals so's I can code around their headers.
