bli@aludra.usc.edu (07/07/90)
I was wondering if anyone here knows how Newtek displays those pseudo-24bit images on the stock amiga, and in hires? I for one am intersted in displaying 8-bit graphics (max 256 colors) on the Amiga, at 640x400. Can anyone suggest a way to do that? What does Newtek do to hog the whole amiga while displaying the pic? I suppose it must do quite a lot of dithering (anyone knows what kind?) and I heard that it also does Gamma correction. Is that all? Thanks. (p.s. I am asking this, since I remember few months ago that there was a lot of talk (and flaming) on c.s.amiga about the 'kludgy' display modes, and a number of people claimed that they can write their own, but will not because they don't like the concept. Well, like a previous question here about writting self-modifying code, pretend this is for purely academic reasons.) P.p.s. will forward all worthwhile mail responses. Posting is fine for me, but I don't know if others are interested.
visinfo@ethz.UUCP (VISINFO c/o Sascha Schnapka) (07/17/90)
In article <10670@chaph.usc.edu> bli@aludra.usc.edu writes: >I was wondering if anyone here knows how Newtek displays those pseudo-24bit >images on the stock amiga, and in hires? As far as I know they use a different color palette on each line. They are still limited to 16 colors in one line. So you can use Dyna-HIRES only for pictures with limited color information. Now I'm coming to the point of this posting. I think the way NewTek does their Dyna-HAM and Dyna-HIRES is not a good idea. 1. The Dyna-Modes are not compatible with multitasking: Both Dyna-Modes use a lot of processor time to swap the colors on each line. It is theoretically possible to write a Dyna-Show programm that allows multitasking while vertical blanking, but even this would slow things extremly down. 2. The Dyna-Show programm is not compatible with future Amigas. The first version didn't run on '020 and '030. The current version is not compatible with the Amiga 3000 because they depend on the Chip Memory timing of the 16 bit Amigas. I think a solution to this could be that all Amiga users try to convince NewTek and other companies to support not the Dyna-HAM but the SHAM- standard. As far as I know the SHAM-standard does not come from a comercial product. The idea to increase the sharpness of HAM pictures using different color registers on each line is great, but the implementation of SHAM has some advantages over Dyna-HAM. Because it is not possible to change all 16 color registers with the Copper, NewTek had to use the processor to support the Copper. The SHAM standard solves this by only changing all foreground colors. These 15 registers can be managed by the Copper alone and you have no problems with multitasking and if you make the Copper list with the Operating system, it will be compatible with future Amigas and Operating Systems. ShowIFF by Chris Weber shows that this is possible and that it is the way to go. You notice a big speed increase when you try to drag a SHAM screen with a user copper list when you run ShowIFF on the Amiga 3000 under 2.0. The win of one color when using Dyna-HAM instead of SHAM is really not worth to give up multitasking. SHAM is really great (I have converted several GIF pictures which look great) and fully multitasking compatible. I could be even possible to write a Paint Program for SHAM pictures, because the program itself can run in fast memory and doesn't loose any CPU cycles. Of course the screen handling would be slower compared to a HAM Paint program because of the user copper list. >I for one am intersted in displaying 8-bit graphics (max 256 colors) on the >Amiga, at 640x400. Can anyone suggest a way to do that? What does Newtek do >to hog the whole amiga while displaying the pic? I suppose it must do quite >a lot of dithering (anyone knows what kind?) and I heard that it also does >Gamma correction. Is that all? The concept of SHAM could probably also be used for hires. This would give us a SHIRES standard with the same advantages of SHAM. Chris Weber has once tried to create SHIRES but it doesn't work yet. I would really like to see that SHAM and may be SHIRES would become standards on the Amiga for displaying 12-Bit Graphics. We must have a standard here like the normal Amiga display modes. This would convince other companies to support such special modes, too. /* -------------------------- SG (Simeon Graphics) ---------------------- */ /* Peter Simeon, UUCP: | // // */ /* visinfo@bernina.ethz.ch | // Long live the AMIGA! // */ /* BIX: hardwiz | \X/ \X/ */ /* ---------------------------------------------------------------------- */
drtiller@uokmax.uucp (Donald Richard Tillery Jr) (07/18/90)
You should be aware that SHAM only changes the palette every other scan line in interlace mode while dynamic HAM can change every line. As for the Sliced Hi-Res mode, I know of at least one group of PD authors who are working on just such a mode. One of them is David Grothe, the author of SuperView, THE best IFF viewer for the Amiga (it also shows anims and brushes, supports extreme overscan and colorcycling and much more). (commercial plug) _______ __________ _/____) ' __ /_/ / ' / / __ _ "N.I.N.J.A.J.I.S."-Me / \___/__/___/ |_ /__/__/__/_/_-_/__/_/ The Displaced Razorback. ___________________________________________/ Founder: IDGAFF Ltd. The Amiga Computer - "...a more fiendish disputant than the Great Hyperbolic Omni-Cognate Neutron Wrangler of Ciceronicus Twelve..." -D.Adams; Well, almost.