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Crazyace

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Posts posted by Crazyace

  1. Posted

    no... they at least invented "soft scroll" register but not like on a8... incl. LMS plus variable screen base adress on word or byte edges.

     

    I'd have been happy with c64 style scrolling on the ST ( with 8 extra bytes fetched per line ) and the ability to change the word address of the screen at any time. The ST had a much faster processor, so the extra work painting wouldn't have been as much of a hassle.

  4. Posted · Edited by Crazyace

    You're doing Chewbacca defense. Either you admit the 16-gray image I posted on from A8 is inferior on ST or you accept that interlacing is allowed. You are maintaining a double standard. We're comparing which palette is superior so that's why it's relevant to compare whether A8 and ST would be better with A8 palette or ST palette. And stop with the crap about 128 colors. Palette on A8 is 256 and on ST is 512. If you can't understand this point, then the rest of the discussion about palettes is moot.

     

    I'd never want to be accused of Chewbacca defense :)

     

    So I'll admit I can't reproduce your 16 shade grayscale image on the ST exactly without interlacing or discolouration( as I said here )

     

    The other way would be to false colour the pallette slightly - so the inbetween shades are slightly off hue.

    RGB's {0,0,0},{0,1,0},{1,1,1},{1,2,1} .... {6,6,6},{6,7,6},{7,7,7} - or some other calibrated pallette.

    There wont be an exact match, and your picture is slightly biased already as it's made for the resolution, rather than being converted from a true colour original.

     

    Now please show me a 176x240x31 shade image - I'm actually just interested in seeing it.

  7. Posted

    Not it isn't. Luminance is more important than chrominance. So palette isn't a clear cut win for ST. Some images may look better but you can't draw a general conclusion without doing a large extensive sampling. For digitized imagery, you can always dither the colors and get more luminance bits.

    If all things were equal in terms of resolution between the A8 and ST the palette choice would be a lot more even - but the A8 is unable to utilise it's pallette freely ( without flicker ) at anything higher than 80 pixels ( 88 with overscan ) which is a major flaw. Also - as monitors are inherently RGB devices I'd say having an RGB palette is better engineering. For NTSC TV ( when the A8 was designed ) the COL/LUM was pretty elegant though.

     

    Circular reasoning. I posted a 16-gray image and you used flickering to represent it on ST. I say then that I can do same on A8 with more shades 176*240*31 and now you claim that's a major flaw. Nice job.

     

    Now the guts of the issue: you have to compare palettes by themselves as I already gave you the benefit that ST resolution is higher. Correct resolution cannot be brought into the picture again. It's called controlled experiment in modern science. And your parrot picture cannot be used as it's based on a 128 color palette. It's not a lot more even, A8 palette will edge it out-- go do the experiment. Also note that you can re-use more colors with 8-bit palette values on ST.

     

    Actually not circular reasoning - I'm just asking you to show me this 176x240x31 shade image.

     

    Regarding the 'guts' - I prefer the 512 colour palette as it is more general purpose - The 128 colour palette on the A8 is still very good, but inferior - and the special 16 shade GTIA mode does offer more shades but with no global colour control, which is a major limitation.

     

    If the ST had the A8 palette we wouldn't be having this conversation :)

  8. Posted

    That's probably why I enjoy playing on the A8 nowadays - when I had the ST it was great , but it was more of a general 'computer' , and there was nothing much to miss moving on to a PC. The A8 ( and the Amiga ) were more like game machines, with lots of custom hardware to play with.

  9. Posted

    Not it isn't. Luminance is more important than chrominance. So palette isn't a clear cut win for ST. Some images may look better but you can't draw a general conclusion without doing a large extensive sampling. For digitized imagery, you can always dither the colors and get more luminance bits.

    If all things were equal in terms of resolution between the A8 and ST the palette choice would be a lot more even - but the A8 is unable to utilise it's pallette freely ( without flicker ) at anything higher than 80 pixels ( 88 with overscan ) which is a major flaw. Also - as monitors are inherently RGB devices I'd say having an RGB palette is better engineering. For NTSC TV ( when the A8 was designed ) the COL/LUM was pretty elegant though.

  10. Posted

    Have you got any 176*240*31 shade images you can post? I can understand 80x240x31 if you interlace 2 gr 9 images together - but how are you achieving 160 pixels with 31 shades?

    With the color clock shift. Can you shift the 320*200 ST screen by 1/640 pixel and get a 640*200*16 shades?

     

    Is that the GTIA mode 10 half pixel offset? - I don't see how you get 31 shades from that - as mode 10 used the palette, which is only 128 colours. ( or are you talking about using horizontal scroll? )

    A picture would be really useful if you have one.

  11. Posted

    But we're talking 176*240*31 shades interlaced so it won't be pixelated.

    Have you got any 176*240*31 shade images you can post? I can understand 80x240x31 if you interlace 2 gr 9 images together - but how are you achieving 160 pixels with 31 shades?

     

    But the parrot is only 128 colors not 256 so logically yes: 64*8 is better than 16*8 palette. But if you had ST use A8 palette, you need to first map to A8 256 color palette and then ST's 512 and then do the compare at same resolution and for many different pictures. The parrot may be artificial as the real world has unlimited shades. The parrot may not even be able to mimic the human voice!

    I'm sorry? You're not really making much sense with the above. ( I guess it may be a joke though )

     

    Another advantage of using A8 256 colors vs. 512 would be that you get more on screen simultaneously per scanline since you can write to two palette entries with one: Move.w #$F03F,$FFFFF240 since each one is 8-bits each.

    That is an advantage - but I think the way forward was to move away from NTSC style encodings - RGB ( even though it only have 8 bits per channel on the ST ) is a better general colour encoding system than the older atari scheme.

  13. Posted

    With newer display devices, it varies; but even with TVs of the 1980s you got around 176*240 visible.

     

    ST wins on resolution, but as I said palette is a trade-off. ST pictures would look better if it has the A8 palette at its high resolution.

     

    And 176*240 doesn't look blocky on TVs or composite monitors but it does look pixelated on a 800*600 VGA display. And many A8 pictures done in interlaced or 80*200 are originals so they are what they are.

     

    Ok - 176 is more realistic. When I first got an Atari the 160 pixel mode didn't seem pixelated, but one more machines were displaying 256 or 320 pixel images it did. 80 pixels always looked pixelated, but it was worth it at the time for the extra colours.

     

    I think most ST pictures would actually look worse if they still used the A8 palette - it wins for the number of shades, but loses out on colours - If you look again at the two parrot pictures the A8 one is noticeably inferior in it's reproduction of reds.

  14. Posted

    By default, all imagery should be taken to be 50/60Hz. Dithered (spatially or temporally) would be a different comparison. A8 by temporal dithering gets 192*240*31.

    192 is pretty high - Is that on any known TV?

    I guess the ST wins out on resolution and size of the pallette, but the A8 has a specific advantage with the 16 shades available in a single colour in graphics mode 9 ( at a quarter of the resolution of the ST )

  15. Posted

    It not only kind of sucks that it only works on 1 bit pair but it's a bit nasty being limited to 128 chars per char bank which means splitting the screen and wasting ram repeating graphics in more than one charset. All round sucky but kind of necessary for anything I've been looking at porting.

     

     

    Pete

     

    Given the way Player pairing works - it would have been cool if the high bit had ored in PF3 with PF0/PF1/PF2 rather than just swapping PF3 for PF2 ... I imagine that would have been really easy to implement as well.

  16. Posted

    CTIA doesn't know graphics modes really so everything is just 3bpp interpreted as: BAK, PF0, PF1, PF2, PF3, Set Hires, Clr Hires, Vsync. Of course, GTIA modes take two consecutive 3bpp and form a 6bpp at 80*240. Only 320*200 takes two of the three bits as two hires pixels.

     

    Does GTIA really give 6bpp? How does that work - I thought it's only 4 bit's max?

  17. Posted

    If you make the shaded image I posted fullscreen (the way it was meant to be) and view the ST image full screen, you can see all the missing shades and how crappy it actually is. I don't know how the other images got into the comparison-- I was giving example of shaded image that looks worse on ST.

     

    I posted two ST versions of your picture? Did you look at both of them? I think the 2nd one actually looked pretty close ( if not identical )

     

    The only way to get the additional shades is to flicker them which won't count as a fair comparison (60Hz vs. 30Hz) since A8 can also do the same.

     

    You posted that picture , didn't say anything about 60/30Hz :) - I'm willing to let you try 30Hz to reproduce the other picture if you like.

     

    The other way would be to false colour the pallette slightly - so the inbetween shades are slightly off hue.

    RGB's {0,0,0},{0,1,0},{1,1,1},{1,2,1} .... {6,6,6},{6,7,6},{7,7,7} - or some other calibrated pallette.

     

    There wont be an exact match, and your picture is slightly biased already as it's made for the resolution, rather than being converted from a true colour original.

  21. Posted

    I find it easier not to argue that point in this case - it just muddies things :) - and to display 5 colours I have to go up to 3 bitplanes ( Funnily enough it was actually quicker to go directly to 4 planes for the Boulderdash scroll code )

     

    Your worse case is yet to come-- combining multiple items from the list.

     

    It's 3bpp for those who know how the AN0..AN2 works per color clock.

     

    Sounds interesting :)

  22. Posted

    If you make the shaded image I posted fullscreen (the way it was meant to be) and view the ST image full screen, you can see all the missing shades and how crappy it actually is. I don't know how the other images got into the comparison-- I was giving example of shaded image that looks worse on ST.

     

    I posted two ST versions of your picture? Did you look at both of them? I think the 2nd one actually looked pretty close ( if not identical )

  23. Posted

    Just out of curiosity, (and sorry if you said this somewhere else), did you convert the Photochrome version from

    a copy that had thousands or millions of colors? (as in an original?). If you converted it from a low-count color

    version, you're not gonna see Photochrome's advantages.

     

    I mean, if I took picture A, made up of 256k colors and converted it, Photochrome will be doing its best, whereas

    if I took picture B, at 128 colors and converted it, the results won't be as good nor it will reflect what the ST

    and Photochrome can do.

     

    Thanks!

     

    The Rescue picture was just the 16 shade A8 original ( 80x200 ) resized to 320x200 16 shade, and then saved as a 24 bit TGA. So I wasn't expecting anything from it.

    The Battlestar picture came from the web somewhere - ( I just google image searched for spaceships , and the Galactica is a bit more interesting than the Enterprise ) , the jpg is the original resized to 320x200 true colour.

  24. Posted

    Hmm we are talking about the A8 here? I wouldn't class a 2bpp + msb of char index to be 3bpp at least not in the way it sounds if it isn't fully explained to people.

     

     

    Just out of interest here's an APAC Battlestar..

     

    post-23959-126227284057_thumb.png

     

    Pete

     

    Cheers for that - I think the pictures show a valid comparision between the two machines quite well :)

     

    I find it easier not to argue that point in this case - it just muddies things :) - and to display 5 colours I have to go up to 3 bitplanes ( Funnily enough it was actually quicker to go directly to 4 planes for the Boulderdash scroll code )

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