ivop Posted August 13, 2015 Share Posted August 13, 2015 (edited) Hi, Here's two 160x240 no-flicker "new graphics modes" I have been experimenting with. Funny thing is, the viewers are identical. The conversion routines are totally different though. More info and sources will follow... black and white (8 shades of gray) 6 images, e.g. color (guess how many colors ) 8 images, e.g. Best viewed on real hardware and period display bw.zip color.zip Edited August 13, 2015 by ivop 18 Quote Link to comment Share on other sites More sharing options...
pirx Posted August 14, 2015 Share Posted August 14, 2015 moar info pls! Quote Link to comment Share on other sites More sharing options...
snicklin Posted August 14, 2015 Share Posted August 14, 2015 Very impressive - it looks like you've made a breakthrough here. Quote Link to comment Share on other sites More sharing options...
Marius Posted August 14, 2015 Share Posted August 14, 2015 Very nice, especially the black and white pictures. You are doing a great job for the a8 scene Ivo! Quote Link to comment Share on other sites More sharing options...
AtariTexas Posted August 14, 2015 Share Posted August 14, 2015 2 Quote Link to comment Share on other sites More sharing options...
popmilo Posted August 14, 2015 Share Posted August 14, 2015 (edited) Nice images Ivop! B&W are looking cool. Breaking bad one is great! Standalone converter would be really nice to have Looking at code looks like what we've been doing before and called it "Palblending". Bitmap mode with color changes each scanline. And I remember Polish coders were doing it earlier with Paint program and demo pictures. Some examples taken from games are here: http://atariage.com/forums/topic/197450-mode-15-pal-blending/?p=2609821 ps. Whole topic is interesting, there are even examples of scrolling game if I remember correctly ... Edited August 14, 2015 by popmilo Quote Link to comment Share on other sites More sharing options...
+Ripdubski Posted August 15, 2015 Share Posted August 15, 2015 Nice! Quote Link to comment Share on other sites More sharing options...
ivop Posted August 19, 2015 Author Share Posted August 19, 2015 Sorry for the long delay. I expected to post "how it's done" earlier, but life got in the way. So, here's how it's done The color mode does resemble PAL-blending a bit, but instead of doing APAC in graphics 15, which I also did before, I wanted a mode that did not have every other line without any luminance. So instead of mixing a line of luma only with a line of chroma only, I wanted both lines to have both components somehow. Going the RGB route would need three lines and looks horrible. I also did not want to page flip, which, especially on PAL, flickers horribly. Then I thought of YUV. One line contains YU and the other YV. The conversion is pretty simple with some command line fu [1] (mainly netpbm) Convert image to planar yuv Make a copy On the first image, set the V channel to 128 (assuming 8-bit per component) On the second image, set the U channel to 128 Convert both back to RGB Quantize both to 4 colors Select the 8 closest colors from the GTIA palette (sometimes ignoring all gray values and sometimes ignore some purples to improve color spread) Convert both images to Atari's graphics 15 paletted format, optionally use dithering or use spatial color quantization with built-in dither Lastly, interleave both images, i.e. take line 1 from image 1, line 2 from image 2, line 3 from image 1, et cetera That's it. The viewer just switches between two palettes every scan line. Last Saturday, at the computer club we checked a whole bunch of Atari computers and monitors and this mode is highly dependent on a decently tuned GTIA and looks only mediocre on a TFT screen anyway. A CRT is needed for the full effect As for the 8 shades of gray mode, this was actually a by-product of the above. The odd lines use a palette of 0,4,8,12 and the even lines use 2,6,10,14. Always. Conversion is even simpler. Just quantize and dither two copies of the same image, each using one of the two mentioned palettes. After that, interleave, and so on... [1] https://xkcd.com/196/ 7 Quote Link to comment Share on other sites More sharing options...
pirx Posted August 20, 2015 Share Posted August 20, 2015 Ingenious! I had a similar idea but much less educated, unfortunately pic lost. Basically get a picture without red colour (RED IS BAD) and then do the interleaving with green and blue lines. It is not that bad on pictures with sky and forest YU / YV much cleverer Quote Link to comment Share on other sites More sharing options...
Rybags Posted August 20, 2015 Share Posted August 20, 2015 Can you see how it goes on that "Fascinating" Spock picture posted further up. Quote Link to comment Share on other sites More sharing options...
ivop Posted August 24, 2015 Author Share Posted August 24, 2015 Sure. I forgot one step in before mentioned procedure: pre-process your image with The Gimp/Photoshop/whatever and crank up the color saturation. No dither, netpbm quant: FS dither, netpbm quant: SPQ, 0.9 dither factor As before, looks best on CRT. spocks.zip 4 Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted August 26, 2015 Share Posted August 26, 2015 Not only looks better, but has a nice space saving way of doing it! Good choice! The method seems closely related to what some of the very early web cams used. Quote Link to comment Share on other sites More sharing options...
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