Amiga 500 can do it too - display Revision 2017 modern graphics compo pictures
 

Hello Gentlemen (and Ladies if they are any ;-)

Revision 2017 is over and provided us plenty of new scene meat. After watching modern graphics compo i thought it might be a good idea to display them on our good old 30 years old Amiga to proove how innovtive it was back in those days.
I recently developed a way to convert rgb24 pictures into HIRES OCS standard which not only looking good but is also EXTREMALLY compressible, which is important if we want to fit into single 880kb disk.

We can have all 12 Revision 2017 modern graphics compo pictures packed to 662kB which leaves plenty of room for other demo stuff.
What i am looking is a coder who likes this idea and wants to create slideshow and maybe some demo too with me.
IF you are interested let me know.

Greetings
PS. For those who think it is easy to combine quality conversion with size you are free to challenge me. I put here two pictures

That's a great initiative! I attended Revision and it was a great party! (even though my music release was not through the preselection) - and I would be happy to check this kind of gfx on my good old amiga!!

I might be interested if you'd provide original graphics, but just using converted pictures is a bit pointless (especially if you don't get the approval from all the original artists).

Well, everything released on those parties are Public domain by definition.
Noone is talking about stealing anything, every author would have its credit. The only alteration i do is croping from 16:9 to 4:3 (640x480) but we can also have it in 16:9 using hardware scrolling (848x480)or smaller screen area (704x400).
Its just what it is - Revision compo displayed on small Amiga packed on single disk. In order to start thinking about it, you must have very high compression ratio and good picture quality, but this is what i provide.

The compression ratio i achieved on those pictures are top notch as i have already disscussed them with some of the authors of png optimisers.
You are so famous coder i never dreamed you would be interested, but if you are the final effect could be something more just the Highres slideshow.

They're definitely not public domain

I wasn't talking about stealing. But I do think it's common decency to ask the original artist if they're ok with their work being displayed in a modified form (in this case looking worse than originally intended, even if it's nice for A500 standard).

You're converter seems to give pretty decent results, so I would definitely be interested in creating a souped up slideshow if original content would be shown.

16 Colors? Looks very nice, almost Pixel Art.

Will you provide, create, conversion tool sometime in the future?

Hmm, it is interesting topic for lawyers about what legally are those production, but i doubt we should disscuss it here. What is clear is that whenever you decide to start in that compo you are giving permission that your work will be publicly available on dozens of servers and everyone can display them. I display them just on 30 years old computer and if you would for example try to display full color picture on 256color display you would do the same thing i do. I am just doing it better ;-)

of course good behaviour would requie that we should ask authors about permission but this is not a problemm of will, but more practical - how to contact them ;-)

Thanx for your appreciation of my work. Indeed if you have about 50kB for fullscreen highres picture you can think about making something decent with them.
Revision pictures are my idea coz in fact i discovered them recently. While i liked demos for ages i never really watched compo pictures. Slideshow is an idea how to present them to larger audience,

Well it took me a while to "develop" this so i would like to have some "fame" out of it, but after some production there is really not a problemm to explain it publicly so more people will start using it. You can have higher quality conversion with those pictures but they will be far less compressible.

I think that it is common sense that, especially in the demoscene, none of the artists would have a problem if their work is shown on an amiga slide show disk. The only thing I would make sure is that they get credited, and stated that the images have been converted to low-color Amiga format (which is also common sense).

If their work was used in a commercial product to make tons of money and the original artist wouldn't get a penny, now that would be a whole different story right?

What with more difficult picture? (those two represent special cases easier to convert - IMHO).
Overall i support your efforts - Amiga gfx converters are outdated and based on very ancient algorithms - definitely they not represent current state of science (used color quantization algorithms are quite primitive).

@Trachu

Those results are spectacular, nice job!

Try it in low resolution images, then you can tell the level of quality. In high res the dithering of course is not visible.

I'll give this challenge a shot, although iv'e forgotten all about crunchers...so the sizes are a bit on the big side (under half the size of these PNG's though). I think you can get more than the standard 880k on a non dos disk as well, I guess a scener would know more.

The extra colours are from the copper changing the palette entries. I guess we could have even more colours if someone had written a tool to allow the CPU to change palette entries as well.

Iv'e gone for maximum overscan, as my Amiga is boxed up for recapping, so I had to use my copy on UAE which is set to maximum. I guess file size could come down if the overscan was less.

Has anyone ever done sliced EHB screenmodes?

what about dynamic hires? I posted some of those pictures a while ago. It was impressive, and ran on a vanilla A500.

Tried that, but hamlab+ save file always looked corrupt- in several different viewers. I did do some sliced HAM ones as well. I looked for other programs other than Hamlab+. But all you get typing amiga sliced ham, is spanish girls making sandwiches ;-)




I thought PCHG and Dynamic were the same? Both the images i posted use the copper to add colours- several hundred in hires I think.

Edit; I used XNview to count colours, a good viewer for image reduction, and for IFF in general- doesn't support PCHG though, which is a shame.

I just though sliced/dynamic EHB should be good for demo use as you can load up registers with movem while the display is running and blast it out in the border, and it gives you double the colours for the same work.

If you had some advanced heuristics you could even swap back and forth between HAM and EHB on a line-by-line basis depending on which was deemed better.

Yeah, I read a lot about this on pouet, sadly, all we have to work with are old tools like hamlab+. Of course, in EHB, your limited to low res interlace.

The STE has some great tools using just the processor, i'm sure with CPU+copper we could equal or better some of the conversions on that platform.

Hello Evryone

Thanx for so much input but i have to clear some confusion here.

If someone would ask me which slideshow i know from Amiga, I would go for only one choice:
https://www.youtube.com/watch?v=WfR-KZ3dVFU
Combination of great music and 35 digitised 16colour low resolution pictures combined on 2 floppy discs are doing tits job quite nicelly even today.
I believe if someone wants to make a good slideshow need to combine 3 things:
1. Great music
2. Nice pictures
3. MAximum 2 floppy disc.
There are many productions which do not have even one of those points and are not remebered lost in cyberspace.
I know only one slideshow which uses Hires pictures, but IMHO its not entertaining
https://www.youtube.com/watch?v=reP7ncoDlMw

It is true 1985 computer could display 640x512 with 16colours and even change them dynamically, but it is connected with serious limitations.
1. Memory - 163840Bytes in Chip memory are needed for Frame Buffer
2. Speed - In rastertime of Display area CPU,Blitter,Copper have no access to memory. All is monopolled by Display DMA. The only time when CPU can do something is in offscreen area. Just imagine CPU is working at 20% of its normal speed to understand how hard is to se it.
3. Disk space - High resolution usually requies more space, but Amiga has only 880kB floppy

Lets just examine Khph_re idea from practical side.
1. He has chosen 720x566 resolution which requie 203760bytes frame buffer. His copper lists about 20kB, Music lets assume 100kB. We have left with 180kBytes of Chip and 0.5Mbytes of slow Ram. Chip memory is too low for another frame buffer so we would have to make our music smaller (probably worse quality) or blank the display to load another picture.
2. 720x566 blocks sprites and allows to change only 4 colours in each line by copper and the CPU would work at 10% of original speed. During that time we could play music but what about loading another picture, what about decompressing it? And how to make scroll on it?
3. If he uses 120kB for each picture in compressed form then he could place only 6 pictures on disk. Certainly not enough for good slideshow

In general khph_re idea is purelly theorethical and because he used more than 4 changes in line probably not able to display on standard OCS machine. If he would lower the resolution a bit this could be done, but he would still have not enough pictures, because his pictures compresses to 120kB vs mine 50kB). Of course my fellow amiga friend if you can make me wrong I would be more than happy :)

I think i must explain why my idea is uniqe and complete.
1. I opted for 640x480 which uses only 153600Bytes. Adding to that 100kb for music and 50kB for code would leave 700kB for compressed pictures, so we could load them directly into memory and decompress directly into the same frame buffer during black pauses between pictures.
2. 640x480 still uses a lot of CPU, but it is still some left for music and scroll on sprite layer. Decompression would requie more power but this is possible when we will black the screen
3. Disk space is ok as long as we keep the compression high. PNG i have are just plain chunky pixels packed with optimised deflate algorythm. Their decompression would probably be too long but i have an idea how to pack bitplane IFF to comparable sizes.

As you could see my approach is doneable and would be something unique noone has done before because you just cant do it without good compression. Thats a start and i did it. If someone can help me to finisz this idea he is most welcome.

some good points, I can't answer all of them, as I am an artist, not a coder.
Firstly, these images should work just fine on OCS, if anyone wants to test the IFF's I have them.

880k is the standard workbench format, custom demo scene formats go beyond that.

the images can be further compressed from RAW far better compression than IFF achieves.

I agree that overscan is probably overkill, but I see no reason not to use the copper.

I personally believe you should use ham/overscan EHB or PCHG for high colour, high resolution conversions. (controversial, I know).

interesting thread and software link to this very subject:

http://ada.untergrund.net/?p=boardthread&id=935&page=0

Neither do i but know how memory access on OCS works.
If you have used more than 4 changes per line they wont because there wont be enough DMA for copper, however they could be displayed on AGA
OK, and how many more Dynamic hires pictures will you fit?
You think or you know?
In theory Copper would help quality, in practice your approach has serious disadvantages which makes it inpractical as i have described

Not controversial, simply impossible on OCS. Only AGA can have EHB in High resolution.
:) do not get me wrong. I appreciate your effort and hope you will continue to find something more fit to amiga limitations.