aozer@next.com (Ali Ozer) (06/26/90)
In article <4b28c24a.20b6d@apollo.HP.COM> Steve Rehrauer writes: > ... Spectrum does this, and can switch the palette quickly >enough to let you choose 48 of the possible 512 colors per each of the 200 >lines in a low-resolution screen. ... > ... there are Amiga programs that do similar tricks as Spectrum >does on the ST, giving you all 4096 colors at once. Yes, there are. But you can get 4096 colors at once using the Amiga HAM mode (in 320x400 resolution) without the program doing any tricks or the processor having to do any extra work. This mode essentially compresses 4096 colors (12 bits) down to 6 bits by encoding a pixel color as either one of 16 absolute entries (selectable as first 16 entries in the color palette) or as the previous pixel color plus a replacement of one color component (R, G, B). Photographs of people and scenery and most ray traced pictures end up looking great in this mode; some pictures suffer from fringing effects, though. It's of course true that there are programs that resort to changing the color palette on the fly to give you modes such as 4096 colors at once in hi-res. Ali Ozer
SPLITE@MTUS5.BITNET (06/27/90)
In article <12962@cbmvax.commodore.com>, peter@cbmvax.commodore.com (Peter Cherna) says: > Peter Cherna, Software Engineer, Commodore-Amiga, Inc. > {uunet|rutgers}!cbmvax!peter peter@cbmvax.cbm.commodore.com >My opinions do not necessarily represent the opinions of my employer. >"If you insist on spending $10000 on a 68030 technology, may we humbly >suggest you buy three Amiga 3000's." Hmmm... Seems to be a lot of "propagandizing" on the ol' net lately. Seems like a Commodore engineer would have better things to do than read c.s.a.st. ;-) Now, don't start on me. This is not another shot in the Everlasting Holy War between Atari-types and Commodore-types. I did my time in the trenches, but now I have other concerns than "whose floppy is bigger". The only reason I've brought it up is that all the talk about the merits of the Amiga 3000 would seem to be better placed somewhere else. Yes, it's a neat machine, and dirt cheap besides; but, if a potential TT-er wants to learn more about the A3000, let him read comp.sys.amiga (or Byte magazine). On the other hand, there seems to be little else to do in c.s.a.st besides random flaming, so maybe a little advertising would put the bandwidth to better use. You could even cross-post to misc.foresale.computers. Just one guy's opinion... Steve Plite<SPLITE@MTUS5.BITNET>
ljdickey@water.waterloo.edu (L.J.Dickey) (06/28/90)
In article <90177.185831SPLITE@MTUS5.BITNET> SPLITE@MTUS5.BITNET writes: > ... >The only reason I've brought it up is that all the talk about the merits of >the Amiga 3000 would seem to be better placed somewhere else. > ... >Steve Plite<SPLITE@MTUS5.BITNET> Very p'litely said, Steve. :-)
arc@desire.wright.edu (06/28/90)
In article <196@next.com>, aozer@next.com (Ali Ozer) writes: > In article <4b28c24a.20b6d@apollo.HP.COM> Steve Rehrauer writes: >> ... Spectrum does this, and can switch the palette quickly >>enough to let you choose 48 of the possible 512 colors per each of the 200 >>lines in a low-resolution screen. ... >> ... there are Amiga programs that do similar tricks as Spectrum >>does on the ST, giving you all 4096 colors at once. > > Yes, there are. But you can get 4096 colors at once using the Amiga HAM mode > (in 320x400 resolution) without the program doing any tricks or the processor > having to do any extra work. This mode essentially compresses 4096 colors (12 > bits) down to 6 bits by encoding a pixel color as either one of 16 absolute > entries (selectable as first 16 entries in the color palette) or as the > previous pixel color plus a replacement of one color component (R, G, B). > Photographs of people and scenery and most ray traced pictures end up looking > great in this mode; some pictures suffer from fringing effects, though. > > It's of course true that there are programs that resort to changing the color > palette on the fly to give you modes such as 4096 colors at once in hi-res. > > Ali Ozer Yes, Ali, HAM pics CAN suffer fringes, but if the raytracing programs better selected the palette, there would be VERY few cases of this. I find myself going through some of these raytraces with a paint program and finding that there are like 4 colors in the base palette that remain black. They COULD have used those, but NOoooooo, they're STUPID... BTW, the Amiga, theoretically can have 384 different colors per scanline (max. res. 384x480). And the special thing you were talking about there, was, for these ST people, 768x480 at 16 different colors per scanline. Not bad, but I *THOUGHT* they could have done better.
arc@desire.wright.edu (07/01/90)
In article <2701@mrsvr.UUCP>, krieg@jupiter.uucp (Andrew Krieg) writes: > I recently saw some IFF pictures on my friend's Amiga and was greatly > impressed. They made most of the Spectrum pictures I've seen look like water > colors. Is there a better graphics format than Spectrum for the ST? Does > the Amiga 2000 have a higher resolution than the 520 ST? Is this a result of > IFF displaying more colors or something? > > I also have some GIF pictures I've been trying to view on my ST. I haven't > had much luck with PD GIF viewers, so I used a GIF to Spectrum conversion > program instead. Some of these GIF files were 100-200K, but the Spectrum > pictures produced by the coverter were always around 51K. Needless to say, > the resolution was horrible! Is this a fault of the conversion program? > > Is there anyway to create/view high resolution color pictures on the ST that > approach GIF and IFF? I've been very disappointed with what I've seen so > far. > -- > ========================================================================= > = Andrew Krieg Marvel Historian = > = krieg@ylum.med.ge.com Keeper of: The LIST, 2to1 list = > ========================================================================= > = Sheriff Truman: Do you think they spotted us? = > = Agent Cooper: Gimme a doughnut. - Twin Peaks = > ========================================================================= The IFF pictures you saw were in a format also called HAM. In which the Amiga (ANY MODEL) can display all 4096 colors in a max. res. of 384x480 without doing any weird stuff like Spectrum does. Also, HAM stands for Hold-And-Modify. ------------------------------------------------------------------------ = /// | Bryan K. Fite | Arc@Desire.Wright.edu = = /// Amiga! | ^Service Engineer^ | -or- = = \XX/ The One | Arc Electronics, Inc. | Arc@WSU.BITNET = = ____& Only... | Wright State University |"Ouch! Quit-it." - Bart= = | Dayton, Ohio | Depeche' Mode, Now! = ========================================================================
hyc@math.lsa.umich.edu (Howard Chu) (07/02/90)
Well, just to add more deadweight to the dying discussion... I've just finished porting Fractint 12 from MSDOS to the ST, and along the way I added some "new" video modes as well. I added 4-color grayscale to the monochrome resolution, and made the medium resolution 16 colors, and the low resolution has a palette of 256 colors. From my calculations, the available palette is 512 * 511 / 2 = 130816 distinct colors. The 4 color grayscale is nothing wonderful to look at. Downright ugly, to be honest, but it would look good on a monitor with high-persistence phosphor. The low resolution mode looks pretty slick, though. Most of these fractals look really gorgeous with 256 colors. The trick is pretty obvious, it seems. Just use two screens, and flip the physical page on every vertical blank. This effectively doubles the number of bits per pixel, and as expected, squares the number of colors that can be displayed at once on screen. It also introduces an incredibly annoying flicker... But hey, Amigans settle for a megapixel display that updates at 15 hertz, 30 hertz is a lot better. Sending 4 complete screens at 15 hertz on the ST would give, what ... 64K displayable colors out of, oh... 36 bits worth of palette. Not that it'd be incredibly worthwhile.... You'd really need the same kind of monitor that the Amigans use - an intelligent one that assembles the video frames in an internal buffer. Going to monochrome is a slightly different story. If you just use two screens and flip back and forth between them, you'll get dark, half-light, and light. To get 4 distinct levels of grayscale, or to make the significant bits really significant, you have to display them onscreen for a longer period of time. But that's pretty easy too... So, the 70 hertz monochrome video is split up into a low-significance image sent for one-third of the time, or 23.3 hertz, and the high-significance image is sent at 47 hertz. The flicker here is really really noticable. Anything slower than 30 hertz will be, of course. Turning the brightness down or getting a monitor with high-persistence phosphor would cure that problem.... Ok, I guess I've rambled long enough. I've had a lot of fun getting this code working, and I personally think the doubled video modes are kinda neat, even if the monochrome flicker is as obnoxious as a fluorescent light... Now... If you're really really crazed, you can do vertical blank image switching *and* horizontal scan palette switching at the same time. I don't think it's really practical for general purpose drawing, or for drawing fractals either, for that matter. Limiting color selections on a per-scanline basis just seems like too much hassle to deal with. But if you wanted to try it, you could draw yourself... 256 * 3 swaps per line * 200 lines = 153600 colors per screen. I guess that's a bit excessive, given only 130K colors in the palette. SO.... I hope this discussion is really, truly dead now, so we can get to more interesting things. Meanwhile I'll be submitting fractint for posting Real Soon Now. (But sometimes, ya gotta wonder. Why are you spending all these cycles drawing these silly pictures???) -- -- Howard Chu @ University of Michigan ... the glass is always greener on the side ...
arc@desire.wright.edu (07/02/90)
In article <1990Jul2.071658.16558@math.lsa.umich.edu>, hyc@math.lsa.umich.edu (Howard Chu) writes: > Well, just to add more deadweight to the dying discussion... I've just > finished porting Fractint 12 from MSDOS to the ST, and along the way I > added some "new" video modes as well. I added 4-color grayscale to the > monochrome resolution, and made the medium resolution 16 colors, and > the low resolution has a palette of 256 colors. From my calculations, > the available palette is 512 * 511 / 2 = 130816 distinct colors. The > 4 color grayscale is nothing wonderful to look at. Downright ugly, to > be honest, but it would look good on a monitor with high-persistence > phosphor. The low resolution mode looks pretty slick, though. Most of these > fractals look really gorgeous with 256 colors. > > The trick is pretty obvious, it seems. Just use two screens, and flip the > physical page on every vertical blank. This effectively doubles the number > of bits per pixel, and as expected, squares the number of colors that can > be displayed at once on screen. It also introduces an incredibly annoying > flicker... But hey, Amigans settle for a megapixel display that updates at > 15 hertz, 30 hertz is a lot better. Sending 4 complete screens at 15 hertz > on the ST would give, what ... 64K displayable colors out of, oh... 36 bits > worth of palette. Not that it'd be incredibly worthwhile.... You'd really > need the same kind of monitor that the Amigans use - an intelligent one > that assembles the video frames in an internal buffer. > > Going to monochrome is a slightly different story. If you just use two screens > and flip back and forth between them, you'll get dark, half-light, and light. > To get 4 distinct levels of grayscale, or to make the significant bits really > significant, you have to display them onscreen for a longer period of time. > But that's pretty easy too... So, the 70 hertz monochrome video is split up > into a low-significance image sent for one-third of the time, or 23.3 hertz, > and the high-significance image is sent at 47 hertz. The flicker here is > really really noticable. Anything slower than 30 hertz will be, of course. > Turning the brightness down or getting a monitor with high-persistence > phosphor would cure that problem.... > > Ok, I guess I've rambled long enough. I've had a lot of fun getting this code > working, and I personally think the doubled video modes are kinda neat, even > if the monochrome flicker is as obnoxious as a fluorescent light... > > Now... If you're really really crazed, you can do vertical blank image switching > *and* horizontal scan palette switching at the same time. I don't think it's > really practical for general purpose drawing, or for drawing fractals either, > for that matter. Limiting color selections on a per-scanline basis just seems > like too much hassle to deal with. But if you wanted to try it, you could > draw yourself... 256 * 3 swaps per line * 200 lines = 153600 colors per > screen. I guess that's a bit excessive, given only 130K colors in the palette. > > SO.... I hope this discussion is really, truly dead now, so we can get to > more interesting things. Meanwhile I'll be submitting fractint for posting > Real Soon Now. (But sometimes, ya gotta wonder. Why are you spending all > these cycles drawing these silly pictures???) > -- > -- Howard Chu @ University of Michigan > ... the glass is always greener on the side ... Hey, bud, our screens (640x200, 320x200, etc.) update at 60 frames per second. ONLY our interlace mode updates at 30 frames per sec. DON'T even start!!! ALso, we have a blitter and many co-proc's and the ONLY "co-processor" YOU have is a DMA controller, BIG DEAL! Later ------------------------------------------------------------------------ = /// | Bryan K. Fite | Arc@Desire.Wright.edu = = /// Amiga! | ^Service Engineer^ | -or- = = \XX/ The One | Arc Electronics, Inc. | Arc@WSU.BITNET = = ____& Only... | Wright State University |"Ouch! Quit-it." - Bart= = | Dayton, Ohio | Depeche' Mode, Now! = ========================================================================
joe@cbmvax.commodore.com (Joe O'Hara - Product Assurance) (07/03/90)
In article <725.268f2179@desire.wright.edu> arc@desire.wright.edu writes: >In article <1990Jul2.071658.16558@math.lsa.umich.edu>, hyc@math.lsa.umich.edu (Howard Chu) writes: >> You'd really >> need the same kind of monitor that the Amigans use - an intelligent one >> that assembles the video frames in an internal buffer. If I read you correctly here, Howard, you're under a misconception: the standard monitors used on Amigas are not intelligent. They are analog RGB, NTSC or PAL compatible (depending on country). You may be referring to the use of multiscan monitors in conjunction with de-interlacing video cards which buffer interlaced scan lines in local RAM before sending the signal to the monitor to remove the flicker inherent in interlaced NTSC/PAL signals. > >Hey, bud, our screens (640x200, 320x200, etc.) update at 60 frames per second. >ONLY our interlace mode updates at 30 frames per sec. DON'T even start!!! > > ALso, we have a blitter and many co-proc's and the ONLY "co-processor" YOU >have is a DMA controller, BIG DEAL! Later Please, Amiga owners, be polite when visiting other groups. There's no need to start flame wars over differences in various system designs. Leave religious fervor in the realm of metaphysics. -- ========================================================================== Joe O'Hara || Disclaimer: I didn't say that! Commodore Electronics Ltd || Product Assurance || "I never lie when I have sand in my shoes." Systems Evaluation Group || - Geordi LeForge, Star Trek TNG ==========================================================================
watters@penguin.cis.ohio-state.edu (david r watters) (07/03/90)
In article <1990Jul2.071658.16558@math.lsa.umich.edu> hyc@math.lsa.umich.edu (Howard Chu) writes: >Well, just to add more deadweight to the dying discussion... I've just >finished porting Fractint 12 from MSDOS to the ST, and along the way I >added some "new" video modes as well. I added 4-color grayscale to the This seems pretty impressive from the discription. >flicker... But hey, Amigans settle for a megapixel display that updates at >15 hertz, 30 hertz is a lot better. Sending 4 complete screens at 15 hertz This is incorrect. The Amiga monitors refresh at 60Hz, all the time. The screens with Xx400 and greater are interlaced which gives an apparent refresh rate of 30Hz. 1/60th for each of 2 fields making 1 full image refresh at 1/30th. The 1200x400 and greater mode still refreshes at 30Hz, with each pixel having half as much data letting you use 4 colors. 15Hz would be unusable!!! > -- Howard Chu @ University of Michigan{ watters@cis.ohio-state.edu
GRIGSBY@AUVM.BITNET (07/03/90)
Are all Amigans so paranoid that the Atari might have its strengths, too, that you all read atari.st just to make sure no one likes their machine? Fact correction is OK, but the Amiga/ST flame war is DEAD. Don't start it again -- it's what kept us and still keeps us from seriously challenging IBM/Apple. Both machines were rushed to market in buggy versions to compete with each other, and both user communities have flamed each other instead of enjoying their systems. Capishe? -grigsby, a 5 year veteran (now conscientious objector) to this particular war.
galpin@ucscb.UCSC.EDU (Knight of the Mystic Sword) (07/03/90)
I believe that the 15hz mode referred to was the Hedley monitor (1208X800) that uses four Amiga screens to produce one virtual screen. However, with the addition of the Enhanced Chip Set, the Hedley design is almost obsoleted, with the standard 1024 (1174? with overscan) X 400 (470? with overscan) modes available. The Hedley (Moniterm) design is only useful for those who really need a 19 inch four grey scale full page display. I believe that the computer refreshes the display at only 15hz, but the monitor actually refreshes at a significantly higher rate (due to its internal circuitry). The Hedley design is not intended for playing games or doing very much else except for productivity stuff. Because of the way the displays work, only one sprite is supported (the mouse pointer). For the applications that it is designed for, the Hedley's slow screen update should not pose very much of a problem. -Dan (Former Atari 800 enthusiast that now uses the next generation) :-) -- ****************************************************************************** * Amiga // * Short (TM) Signature * DISCLAIMER: * * \\ // * galpin@UCSCB.UCSC.EDU * This space reserved for a * * \X/ Only* COMP. QUOTE: Only time will tell* clever disclaimer someday. * ******************************************************************************
hyc@math.lsa.umich.edu (Howard Chu) (07/03/90)
In article <725.268f2179@desire.wright.edu> arc@desire.wright.edu writes: >Hey, bud, our screens (640x200, 320x200, etc.) update at 60 frames per second. >ONLY our interlace mode updates at 30 frames per sec. DON'T even start!!! > ALso, we have a blitter and many co-proc's and the ONLY "co-processor" YOU >have is a DMA controller, BIG DEAL! Later >------------------------------------------------------------------------ >= /// | Bryan K. Fite | Arc@Desire.Wright.edu = >= /// Amiga! | ^Service Engineer^ | -or- = >= \XX/ The One | Arc Electronics, Inc. | Arc@WSU.BITNET = >= ____& Only... | Wright State University |"Ouch! Quit-it." - Bart= >= | Dayton, Ohio | Depeche' Mode, Now! = >======================================================================== Nice job of cutting down on the quotes there, "bud." Note that I said on a so-called megapixel display. I have it on good authority that the 2024 monitor, which displayes 1024x800 pixels, is only redrawn at 15 hertz. Granted, it's a fair amount of work getting 800K pixels onto a screen, but this display will only spit out 4 gray levels for all that time & effort spent in interleaving frames. My "garbage" Atari with "no coprocessors" puts out an 800x500 monochrome display at 70 hertz. For 4 graylevels I drop down to 35 hertz or so. For me to stoop to the slow redraw speed the Amiga spits out I can gain another frame time, for 16 gray levels. And this is on a stock Atari monochrome monitor, not some jazzed up $700 "megapixel" tube. I didn't bring this up to dump on your machine, I was merely quoting a figure for the sake of comparison. No need for an antagonistic attitude... [But since you brought it up ... *One* DMA controller is more than adequate, given a powerful enough selection of devices attached to it. In my case, I happen to have a NeXT box attached to my ST, and I've found it pretty adequate for most of my multiprocessing needs.] -- -- Howard Chu @ University of Michigan one million data bits stored on a chip, one million bits per chip if one of those data bits happens to flip, one million data bits stored on the chip...
SPLITE@MTUS5.BITNET (07/04/90)
In article <13008@cbmvax.commodore.com>, joe@cbmvax.commodore.com (Joe O'Hara - Product Assurance) says: > >Please, Amiga owners, be polite when visiting other groups. There's no need >to start flame wars over differences in various system designs. Leave >religious fervor in the realm of metaphysics. >-- >========================================================================== > Joe O'Hara || Disclaimer: I didn't say that! > Commodore Electronics Ltd || > Product Assurance || "I never lie when I have sand in my shoes." > Systems Evaluation Group || - Geordi LeForge, Star Trek TNG >========================================================================== > Thank you, Joe. That should be worth a Nobel Peace Prize. ;-) Kinda funny, what with Communism in decline, the environment a mess, the drug problem, etc., etc., that we get all hyped over how many MegaFroznits our monitors run at, eh? A little cooperation amd respect would go a long way. (Besides, we _should_ be beating up on MS-DOS users! ;-) Steve Plite <SPLITE@MTUS5> "Don't shoot me, I'm only the consultant"
daveh@cbmvax.commodore.com (Dave Haynie) (07/06/90)
In article <1990Jul2.071658.16558@math.lsa.umich.edu> hyc@math.lsa.umich.edu (Howard Chu) writes: >The trick is pretty obvious, it seems. Just use two screens, and flip the >physical page on every vertical blank. This effectively doubles the number >of bits per pixel, and as expected, squares the number of colors that can >be displayed at once on screen. It also introduces an incredibly annoying >flicker... But hey, Amigans settle for a megapixel display that updates at >15 hertz, 30 hertz is a lot better. You're confused about the Amiga megapixel display. While it's true that the entire display is logically updated at either 10Hz or 15Hz (selectable), the actual video refresh rate (eg, will it flicker?) is 60Hz in the 1008x800x2 mode, and 50Hz in the 1008x1024x2 mode. You don't see any flicker on these displays. But they're not suitable, in the high resolution modes, for real time on screen animation. Not that anyone using a monochrome display is all that concerned about animation anyway. The simple case of the mouse pointer "animation" is handled by "mouse-tracking", where the quadrant or sextant of the logical screen containing the mouse pointer is updated more often. Note that, to the system, the screen looks just like you'd expect a megapixel screen to look, it's only the actual screen driver that must perform any special tricks to display on one of these monitors. > -- Howard Chu @ University of Michigan > ... the glass is always greener on the side ... -- Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests" {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: hazy BIX: hazy "I have been given the freedom to do as I see fit" -REM