spinner@wpi.WPI.EDU (Bevan R S Wang) (04/12/91)
I need to know how many colours (the colour palette) is on the NeXT ColorSystem. I have called NeXT five times already and I get a different answer every time.... so far I NeXT says: It has a palette of 4096 and you can have 256 colours on the screen at once. It has a palette of 16.2 million and 256 colours at once. It has a palette of 16.2 million with 4096 colours at once. Now I doubt the last one, but the first sounds "dinky" and the second sounds about right. Any help will be appreciated....thanks in advance Bevan Wang -- _______________________________________________________________________________ Bevan R.S. Wang Internet: spinner@wpi.wpi.edu America Online: Bevan Wang
robertl@bucsf.bu.edu (Robert La Ferla) (04/13/91)
I think the problem stems from the definition of a color palette. There are two types of palettes, software and hardware. The hardware palette is what the video hardware can reproduce on the screen independent of the actual colors that your monitor can reproduce. The software palette is known as the "color wheel" and allows you to select colors from a virtual palette. The virtual palette is 32 bit color (24 bit color + 8 bit transparency) for a total of 16,777,216 colors plus transparency. The NeXTStation Color has 16 bit color which is 4 bits red, 4 bits green, 4 bits blue and 4 bits transparency (alpha channel) The color content is then 12 bits so 2^12 = 4096 colors available on the hardware color palette. The number of colors available on the screen at once is 4096. Please note that the NeXTStation Color uses dithering to give the impression of more colors (32 bit color.) The NeXTDimension has 32 bit color which is 8 bits red, 8 bits green, 8 bits blue and 8 bits transparency. The color content is then 24 bits so 2^24 = 16,777,216 colors. The number of colors on the screen is limited to the number of pixels on the screen because there are less than 16,777,216 pixels. How could you display more colors than pixels given a single monitor? You can't. Robert La Ferla Lotus Development Corporation Advanced Technology Group / Improv #include <std.disclaimer>
sstreep@elvis (Sam Streeper) (04/14/91)
In article <SPINNER.91Apr12100158@wpi.WPI.EDU> spinner@wpi.WPI.EDU (Bevan R S Wang) writes: > > I need to know how many colours (the colour palette) is on the > NeXT ColorSystem. I have called NeXT five times already and > I get a different answer every time.... so far I NeXT says: > > (blah blah blah)... The display hardware is 12 bits (4 each of red, green, and blue) meaning any pixel can be any of 4096 colors. You are actually pretty well insulated from the hardware, though; Using postscript, you can set any color you desire, and things will be drawn using a dither pattern that most closely approximates the set color. The result is that you "apparently" get a lot more than the actual 4096 colors, and the display is not grossly different from a 24 bit display (where any pixel can be one of 16 million colors) ----- Begin wayward color lookup table discussion -------------- By the way, NeXTstation hardware does NOT utilize color lookup tables. In other words, every pixel has a specified color rather than an index into a table that specifies the color. If a system has 256 colors onscreen from a pallette of 4096, that means every pixel has 8 bits specifying an index into a color table with 256 entries, each of which is a 12 bit color specification. Color lookup tables have a few keen features, but they can also be a big pain in the rear. -sam -- Opinions are not those of my employer. They're not even mine. They're probably wrong besides. How did they get in here, anyway?
mitroo@magnus.ircc.ohio-state.edu (Varun Mitroo) (04/14/91)
In article <495@rosie.NeXT.COM> sstreep@elvis (Sam Streeper) writes: >By the way, NeXTstation hardware does NOT utilize color lookup tables. >In other words, every pixel has a specified color rather than an index >into a table that specifies the color. > >If a system has 256 colors onscreen from a pallette of 4096, that means >every pixel has 8 bits specifying an index into a color table >with 256 entries, each of which is a 12 bit color specification. Color >lookup tables have a few keen features, but they can also be a big pain >in the rear. > Does this mean that the color station is capable of only displaying 16 shades of gray? That seems quite limiting for some uses. -- Varun Mitroo mitroo@magnus.acs.ohio-state.edu
dejnsen@caen.engin.umich.edu (Nik Anthony Gervae) (04/14/91)
In article <SPINNER.91Apr12100158@wpi.WPI.EDU> spinner@wpi.WPI.EDU (Bevan R S Wang) writes: > > I need to know how many colours (the colour palette) is on the > NeXT ColorSystem. I have called NeXT five times already and > I get a different answer every time.... so far I NeXT says: > > It has a palette of 4096 and you can have 256 colours on the > screen at once. > > It has a palette of 16.2 million and 256 colours at once. > > It has a palette of 16.2 million with 4096 colours at once. > > > Now I doubt the last one, but the first sounds "dinky" and the > second sounds about right. > > Any help will be appreciated....thanks in advance > > Bevan Wang >-- Three Strikes! NeXTstation color is 16-bit color, with no (to my knowledge color lookup tables), so you get 4096 colors plus transparency, and you don't get any others. The 4096 colors are, as far as I know, hard coded/wired into the system. You get all 4096 at once, and that's it. Now the NeXTdimension has all those 32 bits at once (but as someone else said you can't have any more at once than the number of pixels you got on screen!). With a base color system offering 4096 different on-screen colors, I'm not gonna complain (even though I can't afford it...besides, I'd get a NeXTdim first--save up my money. You'll want an OD of some sort for work with 32-bit color (or even 16)). Happy painting! Nik -- / Nik Gervae aka dejnsen@caen.engin.umich.edu | "It'll be finished next week, \ | CS/Linguistics stud. & NeRD at UM (go blow) | I promise!"--me | | | | | **When all else fails, bug someone who | "Just say an iguana chewed | \ knows (not me!). | up your textbook."--Jason Fox /
edwardm@hpcuhe.cup.hp.com (Edward McClanahan) (04/18/91)
Sam Streeper explains: > ----- Begin wayward color lookup table discussion -------------- > > By the way, NeXTstation hardware does NOT utilize color lookup tables. > In other words, every pixel has a specified color rather than an index > into a table that specifies the color. > > If a system has 256 colors onscreen from a pallette of 4096, that means > every pixel has 8 bits specifying an index into a color table > with 256 entries, each of which is a 12 bit color specification. Color > lookup tables have a few keen features, but they can also be a big pain > in the rear. This may be misleading, however. Just because a system can display all 4096 possible colors on the screen at the same time (from a "pallette" of 4096 colors) does not mean it LACKS a Color Lookup Table. One justification for a CLT pointed out several months ago that it can be used to tweak the mapping (away from 1-to-1) to allow for deficiencies in the D->A converter and the relative strengths of the RGB guns (as well as the surrounding lighting). Also, it is possible to modify entries in the CLT during the page update cycle (i.e. as the display hardware is reading the pixel "values" from memory, using these "values" to index into the CLT to find the Digital RGB values to convert to Analog values to send to the RDB guns in the monitor). Obviously, this method must be applied every screen refresh (30-?? times per second). So, I still have not heard a definitive statement as to the lack or existence of a CLT on the NeXT (4-bit mono, 12-bit color, or 24-bit color). Does anybody know for sure? =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Edward McClanahan Hewlett Packard Company -or- edwardm@cup.hp.com Mail Stop 42UN 11000 Wolfe Road Phone: (480)447-5651 Cupertino, CA 95014 Fax: (408)447-5039
tgingric@magnus.ircc.ohio-state.edu (Tyler S Gingrich) (04/20/91)
In article <32370001@hpcuhe.cup.hp.com> edwardm@hpcuhe.cup.hp.com (Edward McClanahan) writes: >Sam Streeper explains: > >> ----- Begin wayward color lookup table discussion -------------- >> >> By the way, NeXTstation hardware does NOT utilize color lookup tables. >> In other words, every pixel has a specified color rather than an index >> into a table that specifies the color. >> >> If a system has 256 colors onscreen from a pallette of 4096, that means >> every pixel has 8 bits specifying an index into a color table >> with 256 entries, each of which is a 12 bit color specification. Color >> lookup tables have a few keen features, but they can also be a big pain >> in the rear. > >This may be misleading, however. Just because a system can display all >4096 possible colors on the screen at the same time (from a "pallette" of >4096 colors) does not mean it LACKS a Color Lookup Table. One justification >for a CLT pointed out several months ago that it can be used to tweak the >mapping (away from 1-to-1) to allow for deficiencies in the D->A converter >and the relative strengths of the RGB guns (as well as the surrounding >lighting). > >Also, it is possible to modify entries in the CLT during the page update >cycle (i.e. as the display hardware is reading the pixel "values" from >memory, using these "values" to index into the CLT to find the Digital RGB >values to convert to Analog values to send to the RDB guns in the monitor). >Obviously, this method must be applied every screen refresh (30-?? times >per second). > >So, I still have not heard a definitive statement as to the lack or >existence of a CLT on the NeXT (4-bit mono, 12-bit color, or 24-bit color). >Does anybody know for sure? > Just to add fuel to this fire, stir the pot, and generally create havoc and confusion throughout the civilized world........ The following is taken (without permission) from the NeXT add on pages 32/33 of volume 5 number 14 MacWEEK (4/16/91): "...... If, on the other hand, you choose to go the NeXTstation Color route, you'll have the option of enhancing your presentation with your choice of over 4,000 colors from a palette of over 16 million. ...." So, either the color station does some sort of 'color-lookup' or the marketing folks at NeXT don't know their machines. (Yes, I agree, this is VERY possible) Tyler PS: I've seen a demo color station. I WISH I could afford one. All I have is a mere NeXTStation..... :-) :-) :-)
jfreem@uncecs.edu (Joe Freeman) (04/21/91)
You always wonder, when replying to a message posted from a competing company, whether they have a machine or are doing corporate research. The Color Lookup Table (CLT) question is actually a two part question. 1) Does the NeXTStation Color use a CLT 2) Does the user have access to it. The NSC is a 12 bit display that can do 4096 simul. colors (4 bits rgb). The system software has postscript interpolate for all color values not in the base palette. This allows smooth blending from one color in the CLT to another. A user just asks for a color and the system returns closest. The whole idea is to get nice color, avoid hardware depend. and stop the flashing window syndrome. You know, where you go to some workstation, set the colors for one widnow and all the others change colors because they lost their colors in the CLT. The actual colors on the display are created using RAMDACs with more than 4 bit resolution. Extra bits are used for gamma correction, compensation for non linearity in the displays. The CLT is not accessable by users or their programs. Animation should probably be done with compositing. (I think the above information is correct. But, who knows.) -- Joe Freeman jfreem@uncecs.edu The opinions espressed here are my own and are not shared by my employer or anyone else I know of. Flames can be mailed to me or routed to /dev/null.