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-TreasureIsland.png >>>> >>>> The www.vgmaps.com site has quite a few more cool maps (for example the >>>> Flashback ones in my previous post). >>>> >>>> >>>> Stefan >>>> >>>> >>>> -----Original Message----- >>>> From: owner-sam-us...@nvg.ntnu.no [mailto:owner-sam-us...@nvg.ntnu.no] On >>>> Behalf Of Andrew Park >>>> Sent: Wednesday, July 28, 2010 10:29 >>>> To: sam-users@nvg.ntnu.no >>>> Subject: RE: Dizzy (was: Porting spectrum games...) >>>> >>>> It is great to see some activity on here again, 1 quick question where did >>>> the amiga dizzy map come from to get screens, i've been looking for good >>>> amiga screenshot maps everywhere as i'm not an artist and this stops me >>>> writing games, i like to see graphical progress when i'm writing. >>>> >>>> Anybody send me a link? >>>> >>>> Andy >>>> >>>> -----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 00:11 >>>> To: sam-users@nvg.ntnu.no >>>> Subject: Re: Dizzy (was: Porting spectrum games...) >>>> >>>> Actually, late night spurt - with Huffman trees it's 5,528 bytes and >>>> 6,653 bytes respectively. No predictor yet. The former technically >>>> beats the PNG size, but I'd imagine that just means the predictor is >>>> barely going to help and I'm gaining a small win by not including any >>>> of the normal file padding or headers. Or even the palette. >>>> >>>> On Tue, Jul 27, 2010 at 11:47 PM, Thomas Harte <tomh.retros...@gmail.com> >>>> wrote: >>>>> Further to this: I've been playing around with it today using a couple >>>>> of the more complicated screens from that Amiga map which didn't >>>>> feature the watermark (since it's an alpha transparency, causing the >>>>> number of colours to skyrocket), resized to 256 pixels across (which >>>>> makes 141 pixels high). For a sensible lower bound on what I should >>>>> expect, I saved them as PNGs and ran them through OptiPNG, PNGCrush, >>>>> and AdvPNG, keeping the smallest version. >>>>> >>>>> The first (Dylan and a tree) is 5,553 bytes as a PNG. The second >>>>> (featuring the Armorog) 6,108 bytes. >>>>> >>>>> In my quick dash at compression code, I implemented just a trivial >>>>> little LZ77, using an exhaustive search to pattern match and treating >>>>> each scan line as a completely separate thing to compress (and, as a >>>>> result, rounded up to the next full byte). Five bits for a literal, 17 >>>>> for a back reference, the native addressable thing being a nibble. >>>>> >>>>> From that, I got 6,080 bytes for the first screen and 7,170 for the >>>>> second. And this is without yet implementing a Huffman tree (probably >>>>> best done per screen) or any sort of predictor. >>>>> >>>>> So, it looks like on a 16 colour display the LZ77 may actually be the >>>>> most of it. In which case it's going to be hard to support the >>>>> conclusion that PNG is massively better than the various common >>>>> techniques when the Sam was a going concern. A Huffman tree is an easy >>>>> win and something I'll experiment with tomorrow hopefully and a >>>>> predictor is a useful addition even when dealing with hard edged low >>>>> colour graphics because it introduces the second dimension as a going >>>>> concern whereas LZ77 has no concept of that. >>>>> >>>>> Would it be possible to get a single screen hand prepared to be really >>>>> beautiful rather than ripped from a tilemap? >>>>> >>>>> On Tue, Jul 27, 2010 at 10:46 AM, Stefan Drissen >>>>> <stefan.dris...@gmail.com> wrote: >>>>>> Fair enough. You could of course create PNG tiles so that you do not need >>>> to >>>>>> Flash! anything. You could then even also use a 256-colour PNG image as >>>> map >>>>>> editor, the colour determining the tile... ;-) >>>>>> >>>>>> Flashback would be very cool - on the PC I don't remember it having >>>>>> scrolling. You would however also need to create an animated PNG / MPEG >>>>>> player for the animated sequences. >>>>>> >>>>>> Lots of fun things to do... :-) >>>>>> >>>>>> -----Original Message----- >>>>>> From: owner-sam-us...@nvg.ntnu.no [mailto:owner-sam-us...@nvg.ntnu.no] On >>>>>> Behalf Of the_wub ! >>>>>> Sent: Monday, July 26, 2010 19:21 >>>>>> To: sam-users@nvg.ntnu.no >>>>>> Subject: Re: Dizzy (was: Porting spectrum games...) >>>>>> >>>>>> If png's can be used then I think we should do it even if using an >>>>>> image of tiles is a bit ironic! It would allow changes to be made to >>>>>> the image in the gimp rather than flash! if nothing else! ;) If a >>>>>> success, I don't dare to dream about scumm but another possible port >>>>>> would be Flashback, I can't remember how much if any scrolling is in >>>>>> there but something would be possible if pngs could be used as source >>>>>> gfx... >>>>>> I don't know enough to comment on the feasibility of it all but I do >>>>>> have a question, why use the PC bitmaps and not the ST? The Atari is >>>>>> already 16 colours and it would be easy enough to fancy them up a bit, >>>>>> make them a bit less tiley.. I'm saying this without having a good >>>>>> look at how the PC gfx would work in 16 colours though... >>>>>> >>>>>> Hey Warren! I'd guess that whichever direction the project goes >>>>>> there'll be tons to do. The more the merrier I say :) >>>>>> >>>>>> >>>>> >>>> >>>> >>>> >>> >> >> >> >> >
