They're 16 colour (quite poorly in one case), but not necessarily using colours actually available on the Sam's. I've appended the correct number of bits to store a Sam palette after the compressed region.
I've also discovered a bug that makes all my numbers worse. I'm tapping this on the bus so can't give you actual numbers but it's of the order of 6.something kb for the first and 7 or 8 for the second. I'm hoping to be able to shrink again, as right now I'm doing no better than standard deflate, I think. On Friday, July 30, 2010, Adrian Brown <adr...@apbcomputerservices.co.uk> wrote: > Thanks, ill have a quick go. The only thing wil be PNG is a very good format > for compression. Are these colour reduced to sam already or not? > > Adrian > > -----Original Message----- > From: owner-sam-us...@nvg.ntnu.no [mailto:owner-sam-us...@nvg.ntnu.no] On > Behalf Of Thomas Harte > Sent: 29 July 2010 19:31 > To: sam-users@nvg.ntnu.no > Subject: Re: Dizzy (was: Porting spectrum games...) > > Oh, but I haven't actually tested the output stream yet. So for all I > know, some error is lurking somewhere making my numbers smaller by > accidentally throwing data away... > > On Thu, Jul 29, 2010 at 7:00 PM, Thomas Harte <tomh.retros...@gmail.com> > wrote: >> I'll wager you can do better at compression than I can at present, as >> I'm almost completely new to this. But that makes it interesting. >> >> It's obviously wrong to focus too heavily on any test set, but I've >> bundled together the five images I'm currently testing with, in their >> optimal PNG forms, and uploaded to >> http://members.allegro.cc/ThomasHarte/temp/SamTestScreens.zip >> >> You should get files screen1 to screen5 (two from Dizzy, three from >> Flashback) which as PNGs are sized 5,553, 6,108, 10,643, 10,005 and >> 11,533 bytes respectively. >> >> The only thing implicit in my output data is that the images are 256 >> pixels wide. Not all are 192 pixels high but the height is left >> implicit from the total number of pixels. Palettes are included with >> the images. >> >> With that in mind, I'm currently at 5,531, 7,273, 11,956, 10,538 and >> 12,367 bytes. But still working on it. So I won't take offence if you >> embarrass me thoroughly... >> >> On Thu, Jul 29, 2010 at 4:18 PM, Adrian Brown >> <adr...@apbcomputerservices.co.uk> wrote: >>> I hope these will support the EEPROM highscore saving or similar ;). Ive >>> got some strange compression modes, bung me the image and ill see how well >>> i can compress it. Good to see people looking at the Sam again. Im hoping >>> to get some more time on Sam Uip soon >>> >>> Adrian >>> >>> -----Original Message----- >>> From: owner-sam-us...@nvg.ntnu.no [mailto:owner-sam-us...@nvg.ntnu.no] On >>> Behalf Of Thomas Harte >>> Sent: 28 July 2010 22:31 >>> To: sam-users@nvg.ntnu.no >>> Subject: Re: Dizzy (was: Porting spectrum games...) >>> >>> Hmmm, not doing very well with the Flashback image I chose to test >>> (the top left screen) at all. PNG is 10,649 bytes and I'm 13,507 >>> bytes. But unlike yesterday, that's with the Huffman tree stored >>> (whoops!) and the palette thrown on. I've also tweaked the LZ77 stage >>> a bit, so it's now a 256 pixel rolling buffer with repetitions up to >>> 18 pixels in length and the entire screen compressed as one block. >>> >>> That said, at one point the storage space for all three images seemed >>> to go up by about 1.5kb for absolutely no reason. So I don't >>> thoroughly trust my code. >>> >>> I've tried sorting the palette by hue (to give it some sort of >>> likelihood that nearby colours are near each other in the palette) and >>> applying the various PNG prediction filters to the entire image with >>> each and every one causing the file size to grow. Which is quiet >>> probably why PNG picks them line by line. So that's the experiment for >>> tomorrow night... >>> >>> On Wed, Jul 28, 2010 at 10:53 AM, Thomas Harte <tomh.retros...@gmail.com> >>> wrote: >>>> The previously posted Fantasy World Dizzy map seems to have come from >>>> 'Hall of Light', which offers itself as 'the database of Amiga games' >>>> at http://hol.abime.net/. You can't just chop up the map and reuse it >>>> though, as they've watermarked it with an alpha transparency. It's >>>> large but quite spaced out, so I've just used screens that the >>>> watermark doesn't touch. And probably if you had a piece of software >>>> that was at all competent at reducing colour depth then you'd be able >>>> to wash it off again. >>>> >>>> On Wed, Jul 28, 2010 at 10:03 AM, Stefan Drissen >>>> <stefan.dris...@gmail.com> wrote: >>>>> For Amiga Treasure Island Dizzy: >>>>> >>>>> http://www.vgmaps.com/Atlas/Amiga/TreasureIslandDizzy-Trea
