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Forgive me if I'm still in the stoneage, but some years ago I was meddling with mixing graphics modes & exploring mixing colours vertically on the screen. For instance, if you selected graphics mode 15 and plotted a horizontal line of 1 colour and a horizontal line (below this one) of another colour, the visual result would be 1 (thicker) line of a completely different colour, obviously, you can gain a few colours this way, more than the usually allowed amount of colours which is 4, & 5 if you use graphics 12. You can also get different colours if you move these 2 lines down 1 scanline, this way you get a thicker line of an additional different colour again.

With this idea in mind, knowing that in graphics mode 15 the colours would bleed (an old term, I believe the new term is PAL Blending), what would happen if I created a new display list involving alternate lines all down the screen of 2 different modes, graphics 15 and graphics 8 for instance: Poke the graphics 8 background colour to the same background colour of the graphics 15 mode (obviously sorting this out with DLI's will allow you to use the hardware registers of locations 710 & 712 more freely, anyhow, the idea is to hope that the colour from the mode 15 lines will bleed with the plottings on the mode 8 line). As it happens, I tried this & 'bleeding' does not take place, BUT, I have not tried this with any of the other modes, specifically, GTIA modes.

First of all perhaps your asking to what purpose should you want to do this. Well, for instance, if you create a display list of alternate mode lines of graphics 15 and perhaps, the GTIA graphics mode of 16 shades or 16 colours (9 & 11 I believe), then if bleeding takes place, not only will you get 4 colours each with 16 shades, or perhaps you could create with the right colour poking, 16 colours each with 4 shades, perhaps more, BUT, the whole purpose with this is to obtain a higher resolution. Creating alternate graphics 15 mode lines with a GTIA mode line, if bleeding takes place (I'm unsure as I have not yet tried this in practice), then not only will you have the above amount of given colours/shades, but you would be able to create pictures with all this colour at the graphics mode 15 pixel size, if you think about it, every other side of a GTIA pixel is a half sized pixel (graphics 15), so it's true that the picture won't be a real 160 horizontal pixel mode all the way down the screen, but it will be a vast improvement.

I don't get that much time to put my theories into practice, but hopefully I've inspired someone to give it a go and find out whether or not the pixels of these 2 modes really will bleed, if so, then not only will there be more colours/shades, but at a higher resolution too.

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The graphics mode in use doesn't really matter - the TV is doing the blending, not the computer.

 

The colour blending most often used involves alternating scanlines with colour at luma 0 or 2 on one line, and shades of white on the other line.

 

It can be taken further, as you've said - I had a bit of a play with it some time ago and found that different colours with the same luma on alternate scanlines seemed to produce the best results.

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So far, the best applications of this have been the APAC (9+11) and popmilo (15+15 4 color + 4 mono) modes. It could easily work with 15+8, but you would want to add in a instruction that changes register 710 on each line ... on the mode 8 lines it should be the same as the BG color, on the mode 15 lines you can make it whatever color you want. You would also want to keep the mode 15 colors about the same luma as the mode 8 pixels to get blending.

 

Interestingly enough, if you take advantage of artifacting in Graphics 8 (the purple/green effect from plotting in even/odd columns) you get extra colors. But it only works on old CRT's or TV sets.

 

Also, if you use any mode 10 combinations, you will have to shift your mode 15 or 8 pixels one scanline right to get them to match up and correct for the mode 10 shift.

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I wish someone would write a game using the popmilo mode. I think the mocked-up screens looked excellent. Yeah - it's PAL-only, but it was still the most interesting and versatile "new" graphics mode I've seen for a long time (which doesn't flicker).

 

I thought popmilo was writing a game using popmilo mode??

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It's nice to have graphics mode called by your nickname, but I wouldn't go that far :)

 

Its quite simple and Polish guys were doing it for fixed pictures in 90's. One of the earlier is "XL-Paint" demo:

In this preview you can see nice colors without flicker and later with flicker...

Preview: http://a8.fandal.cz/detail.php?files_id=6627

 

Download: http://madteam.atari8.info/uzytki/xlpaint.7z

Docs: http://madteam.atari8.info/xlp.php

 

And yeah, game is coming soon I hope :)

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It's nice to have graphics mode called by your nickname, but I wouldn't go that far :)

 

Its quite simple and Polish guys were doing it for fixed pictures in 90's. One of the earlier is "XL-Paint" demo:

In this preview you can see nice colors without flicker and later with flicker...

Preview: http://a8.fandal.cz/detail.php?files_id=6627

 

Download: http://madteam.atari8.info/uzytki/xlpaint.7z

Docs: http://madteam.atari8.info/xlp.php

 

And yeah, game is coming soon I hope :)

 

This is more like what I believed was possible, I've seen alternate blank lines like that achieved with 256 colour GTIA modes, but this shows that you can blend a GTIA mode with graphics mode 15 and get far more colours at resolution 160 by 192, without blank lines/gaps between picture lines. Alternately, with the colours being the same luma as graphics 8, a graphics 15 & 8 resolution 320 by 192 display can be achieved with 4 colours, and when you introduce the colour pixilating that mode 8 can bring, who knows what you can get.

I wonder what can be done using graphics 8 and 1 of the GTIA modes, does this blend?

Edited by ac.tomo
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What, no love for J.D. Potter's COLRVIEW? It does RGB interlacing in Graphics 8, 9, and 7+. Been around since '92.

 

No, not really. Looks like this kind of RGB interlacing is working much better on NTSC than on PAL machines.

We have heavy flicker and swimming on PAL machines. And on PAL machines we have just some greyscales and no colours in Gr. 8 (whereas we should have up to eight colours). In Gr. 9 we do not have 16x16x16=4096 colours, but something like 3-5 colours in 16 luminances (grey, brown and violet are almost always there). Only the Gr. 15 RGB mode works quite well on PAL colour-wise, but still has lots of flicker and swimming (CIN seems much better here). Last not least, these RGB modes use almost 24k per picture, not very usefull for most games. In the late 90s I converted lots of GIF pics into these RGB modes and err, today I can say the pics do not have that "wow" factor.

 

Personally I prefer CIN, RIP, TIP, HIP, the PAL-blending Gr. 15 mode (also known as *.MAX) and similar gfx modes. Maybe someone could come up with a converter that converts GIF, JPG, BMP or whatever into the PAL-blending Gr. 15 (pseudo-16-colour) mode.

 

The A8 Colour-JPG decoder by Raphael Espino also does Gr. 8 combined with Gr. 11, so we have 16 colours in 2 luminances and 320x192 resolution. Alas, these colour Gr.8 / 11 pics never look good (because theres not enough luminances).

 

Besides, Gr. 10 also does luminance, 8 luminances (9 colours but only 8 luminances!) to be exact and it is also the Gr.-mode which does the GTIA pixel shift which gives us a higher 160x240 pixel resolution. Combined with Gr. 11 (16 colours) and activated GTIA-shift we could have 160x240 pixels with 8x16 = 128 colours, not the same as RIP (Gr. 10 combined with Gr. 9) but very similar...

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Better method than 8/11 is to use 8/10. Especially if you use dithering, you can get good results like these here:

 

http://atariage.com/forums/topic/188370-doing-pictures-using-super-irg-2-and-other-ice-modes/?p=2784316

 

These were in an ICE mode I named PC0, it's a font based mode 10 + mode 0 full frame flicker.

 

Keep in mind in these examples I did used full frame flicker, but it is just as possible to set this up using 8+10 scanline interlace. The only caveat is you have to shift the pixels one color clock (two Graphics 8 pixels) to the right on the mode 8 lines. You also need to alternate PF2 (710) each scanline, on the mode 8 lines it needs to be the same as BAK. On the mode 10 lines you need to set BAK to be the 9th color to get an extra color. Also on the mode 10 lines you will need to alter 709 (PF1) if you want it to be of a different luminance than in mode 8

 

Another project I am working on, is an attempt to get the Commodore 64 pictures I did in ICE PCIN mode (full frame flicker 12+10) to work in a 15+10 interlace:

 

http://atariage.com/forums/topic/188370-doing-pictures-using-super-irg-2-and-other-ice-modes/page-7?do=findComment&comment=3036096

 

 

I think it will look better in 15+10, you get 30 colors, but as there are no color register changes except for BAK (712), everything should blend together with less flicker, especially if you use dithering where the PFx and BAK registers mix. Agauin, the mode 15 lines need to be shifted to the right by one Gr. 15 pixel to correct for the mode 10 shift.

 

And while COLRVIEW is less than practical, it is possible to do a double 9 by alternating BAK between opposite colors on the color wheel (red-cyan, green-magenta, yellow-blue) to get 256 duotone shades. Add PF3 fifth player blending along with PF3 color changes and HPOS changes, and you can theoretically get 1024 colors, although with certain limitations.

 

Also, I need to post up those ICE CHIP mode (11+10 textmode) attempts I did. You can get some nice effects by using non-greys in mode 10, and it's good for drawing fonts and letters against a black background, but the extended resolution is not as apparent as in HIP because mode 11 is only one luminance. Still, it looks better in interlace, I imagine, than full frame flicker.

Edited by Synthpopalooza
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CharlieChaplan ... I know you wanted to see an example of 10+11 using greyscale, so here it is ...

 

In regards to the suitability of CHIP mode (11+10) as I call it, vs Pryzm/PLM/9+11 or whatever you call it, I did a couple of renders for comparison.

 

11+10 (CHIP):

 

post-23798-0-27144800-1406090103_thumb.png

 

 

11+9 (Pryzm/PLM/256):

 

post-23798-0-90140500-1406090128_thumb.png

 

There isn't really much difference between the two, except that with the CHIP mode render, you don't get as many greys, and your color resolution is lower (128). True, there is the pixel shift, but it really isn't apparent here because the lumas on 11 are all exactly the same. It's only really advantageous if you want to use 10+11 to design characters or graphics against a black background. The pictures look similar, with the only evidence of the shifted pixels is against the black part of the mountain.

 

The other possible advantage to 10+11 is if you wanted to get greys in this mode. In 9+11 you have no true greys/whites unless you blend with the background, which makes them dull looking compared to the other colors and it will flicker horribly. In the above renders (which I did using Atari Interlace Studio) the whites and greys get rendered as magenta. So, in CHIP 10+11 you could make some of the color registers use green, instead of grey, to make greys ... magenta and green are opposite sides of the color wheel, and make grey. I did the same picture in CHIP mode but using greens for all luminances above 6 to blend with the sky:

 

post-23798-0-11885300-1406090403_thumb.png

 

Of course in this example, using greens also tints the lower part of the mountain more green as well, so it might be necessary to correct some of the corresponding pixels in Graphics 11.

 

Another example in 10+11

 

post-23798-0-09610200-1406092188_thumb.png

 

Somewhat better, the edges of the rose on the black background and along the bottom show some of the shifted resolution, but the inside of the picture is still showing the 80 column jaggies.

 

So 10+11 doesn't really gain you much in higher resolution, except around the outlines if you are using graphics against a black backdrop. RIP (9+10) seems to do somewhat better in these sorts of pictures with less flicker.

Edited by Synthpopalooza
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So, now all we really need is someone who will step up and create some graphics conversions programs, not just mixing the graphics modes, but adjusting horizontal shift on lines too. Wouldn't it be great if you had a graphics package that took all this into consideration when creating a picture.

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Also, there is a program called Atari Interlace Studio by tebe/madteam (the same people responsible for G2F):

 

http://madteam.atari8.info/index.php?prod=uzytki

(Third from the bottom)

 

It covers the most commonly used modes, Graphics 10, HIP, RIP, Interpainter (15+15 no color changes), .RAW (XL paint 15+15 with color changes), CIN (11+15 64 colors) and Pryzm/Paint 256 (9+11). It does a good job on a lot of these.

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There was also a game called Admirandus (with graphics by emkay), where some of the captions were created as a mix of GR.15+8 modes.

 

I had a quick look at this program on the emulator and although I haven't been able to go further than the title screen as of yet, how did this guy get multi-coloured mode 0 lines (antic 2/or F), this really has got me puzzled, is it alternate mode 15 & 0 (antic E & 2/or F)?

Edited by ac.tomo
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It's because of artifacting ... on CRT or TV screen, you get a different color pixel if you plot in even or odd columns ... on my Atari 1200 XL I think it goes like this:

 

Even column = purple

odd column = green

both columns = white

odd + even column = off white

 

And these colors change if you alter the PF2 (Graphics 8 background) register, or if you use PAL blending from another mode like 15 or 11.

 

You could also do a whole Graphics 8 mode, but Alter PF2 each scanline between opposite colors on the color wheel (blue-yellow, red-cyan, green-magenta) ... with judicious use of artifacting you should be able to get about 16 colors.

 

These colors also vary depending on a number of factors, like model of the Atari, and whether the machine is NTSC or PAL. Apparently the 400/800 series had red and cyan as the artifact colors.

 

You also won't see these colors if you are using an S-Video or other high resolution digital connection mod on your Atari.

Edited by Synthpopalooza
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...how did this guy get multi-coloured mode 0 lines (antic 2/or F), this really has got me puzzled, is it alternate mode 15 & 0 (antic E & 2/or F)?

 

It's all Antic mode 2, just using a DLI triggered right at the top of the screen and running its full height, continually changing the colour registers.

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It's because of artifacting ... on CRT or TV screen, you get a different color pixel if you plot in even or odd columns ... on my Atari 1200 XL I think it goes like this:

 

Even column = purple

odd column = green

both columns = white

odd + even column = off white

 

And these colors change if you alter the PF2 (Graphics 8 background) register, or if you use PAL blending from another mode like 15 or 11.

 

You could also do a whole Graphics 8 mode, but Alter PF2 each scanline between opposite colors on the color wheel (blue-yellow, red-cyan, green-magenta) ... with judicious use of artifacting you should be able to get about 16 colors.

 

These colors also vary depending on a number of factors, like model of the Atari, and whether the machine is NTSC or PAL. Apparently the 400/800 series had red and cyan as the artifact colors.

 

You also won't see these colors if you are using an S-Video or other high resolution digital connection mod on your Atari.

 

 

It's all Antic mode 2, just using a DLI triggered right at the top of the screen and running its full height, continually changing the colour registers.

 

The latter I can understand (flashjazz's expl.) just storing particular colours from a table perhaps so that they stay in place each frame refresh, but with synth's expl. the colour artifacting only apply's to plotted pixels, and those plotted pixels (the text) are mostly 2 mode 8 bits (1 colour clock) wide, thus they would appear white, but, the change in colour is not in the writing as this will always be a luminance of its background colour, but in the background register.

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I had a quick look at this program on the emulator and although I haven't been able to go further than the title screen as of yet, how did this guy get multi-coloured mode 0 lines (antic 2/or F), this really has got me puzzled, is it alternate mode 15 & 0 (antic E & 2/or F)?

 

 

It's all Antic mode 2, just using a DLI triggered right at the top of the screen and running its full height, continually changing the colour registers.

 

Yeah, but it looks like a bunch of crap. It has no meaning or usefulness in the particular application, other than being a technical show of how many colors can be jammed into the mode -- and that not even tastefully. Is there a better example of this technique somewhere?

 

Assembloids on the other hand, shows how mode manipulation can be used to create a useful display that expands the vocabulary of hi-res text in combination with multi-color graphics on the 8-bits.

Edited by MrFish
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