It looks better and it means that the off-the-shelf tools for creating screens are substantially more advanced, being things like Photoshop, and the skills for creating them are much more widespread. If people are willing to help, they just need to use whatever they normally use.
Even at gzip level compression you're probably safe to get the 60 screens of Fantasy World Dizzy onto a disk, so going multiload is a sufficient safety net. Cartoon-style graphics generally compress quite well in any case, so it's not unrealistic to hope that the 60 screens can be stored simultaneously in 512 kb along with the rest of the program. PNG then came into it as evidence of how compact you can make graphics using well-documented algorithms. That I happen to be using screenshots grabbed from tile-based games for testing is just because 16 colour games were often tile based and reducing colour on higher colour screenshots tends to lead to large areas of solid colour that may not be a realistic test. I have also been testing downsampled screens from things like Day of the Tentacle, getting size reductions still in the 40+% range but the tool I have for palette reductions is really rather useless so I'm not putting any substantial weight on that. On Fri, Jul 30, 2010 at 11:20 AM, Adrian Brown <[email protected]> wrote: > Cant remember, was there a reason for individual png and not tile systems > like the originals used. In Flashback (IIRC) it uses multi layer maps > > Adrian > > -----Original Message----- > From: [email protected] [mailto:[email protected]] On > Behalf Of Thomas Harte > Sent: 30 July 2010 11:15 > To: [email protected] > Subject: Re: Dizzy (was:Porting spectrum games...) > > 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 <[email protected]> > 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: [email protected] [mailto:[email protected]] On >> Behalf Of Thomas Harte >> Sent: 29 July 2010 19:31 >> To: [email protected] >> 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 <[email protected]> >> 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 >>> <[email protected]> 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: [email protected] [mailto:[email protected]] On >>>> Behalf Of Thomas Harte >>>> Sent: 28 July 2010 22:31 >>>> To: [email protected] >>>> 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 <[email protected]> >>>> 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 >>>>> <[email protected]> wrote: >>>>>> For Amiga Treasure Island Dizzy: >>>>>> >>>>>> http://www.vgmaps.com/Atlas/Amiga/TreasureIslandDizzy-Trea > > > >
