🚀 go-pugleaf

In article <AM39QBM@math.fu-berlin.de> Andre_Beck@irs.inf.tu-dresden.de (Andre Beck) writes:
>Hi PostScript(tm)-Gurus,
>
>after some discussions to the Color use
>of [X]DPS on colormapped displays (instead of truecolor ones) I came up
>with the thought of
>
> red green blue setXrgbactual pop
>
>would do a color cell allocation for me, with red, green, blue beeing
>some floats 0..1 and the popped bool indicates if it was successful.

Yes, that's correct

>I tried this immediately with dpsexec (a neat client that simply sends
>my trash to the server) and was surprised to get a success indicator even
>if I used floats 0..1 for the rgb values, or f.i. ints like 200, 2000,
>66000 ... i got true.

Neither setXrgbactual nor setrgbcolor nor any of its friends do range
checking.  Any value outside of 0..1 is just truncated.  So the color
(100, -10, -1000) is the same as (1, 0, 0) -- red.

>Does this setXrgbactual thingy do some autoscaling ???

No, just truncation.

>Or is it only defined as { pop pop pop true } on my machine's XDPS
>system ? (DEC 5000 Ultrix 4.3)

No, it works.  Try this code

.3 .4 .5 setrgbcolor
0 0 100 100 rectfill		% see blue-gray dithered square
.3 .4 .5 setXrgbactual pop
100 0 100 100 rectfill		% see solid blue-gray square next to it

The operator WILL return false if your colormap is full and it cannot
allocate the cell.

>At the moment methinks the latter is true, because the following code
>to display colormapped images still dithers its output:

In Level 1 DPS systems, actual cells do not affect colorimage rendering.
Level 2 DPS systems, which will be showing up before too long, allow you to
control the rendering much more closely by using indexed color spaces.

__   -paul asente
\/     asente@adobe.com   ...decwrl!adobe!asente   moo-bear@cs.stanford.edu

The most dangerous creation of any society is that man who has
nothing to lose.				-James Baldwin