Re: gEDA-user: PCB produces invalid postscript

[Karel Kulhavy <clock@xxxxxxxxxxxxx>]

On Wed, Apr 19, 2006 at 05:14:07PM -0400, DJ Delorie wrote:
> 
> > I would like to display the postscript on my laptop. Black means 0
> > photons per some time and white means 100 photons. How many photons
> > is the gray supposed to have per the same time?
> 
> I don't know.  It depends on, among other things, the gamma of your
> monitor and the gamma settings for your X software.  Mine is set to
> 1.5, which gives me a linear response (grey50 is really half-bright).

I asked what the gray is supposed to be. You say that it depends on
the gamma setting of my X software. Supposing is an action of human
mind. Does it mean that the person who decided the postscript generation
can not only remotely read the setting of my X server, but can also
do it against the flow of time?

> 
> Plus, "gray" is a concept, not a specific color.  "0.5 grey" is a
> specific color.
> 
> And, if you care that much about grey levels on your monitor, just
> display some 50% grey next to a 50% black/white dither, and fiddle

What do you mean with "display 50% grey"? 50% of what? 50% of voltage
range on the monitor input, 50% of the numerical range in the video
card, 50% or numerical range in the X application's output range,
or 50% of maximum photon flux?

> with the gamma settings until they look the same.  That's what

I am not going to fiddle with gamma setting of my X server. Setting it
to anything else than turned off causes additional colour rounding in
the display chain and resulting colour resolution degradation.

Instead of this, I am calibrating my display application which is
the Links browser in this case. The browser is performing 48 bit/pixel
dithering for 24 bit/pixel with proper gamma management which I
personally wrote, so the result is perfect without colour fringing even
in the smoothest transitions, and with proper colour hues.

http://links.twibright.com/calibration.html

> everyone else does, because every monitor is a little different.
> 
> What does this have to do with PCB?  The only time non-black is used,

This does have to do with PCB that I am asking what grey the grey
was meant to be. If you want to make the grey with little black spots
on white paper, how many % of area are the black spots going to
take?

> it's not important what the actual grey level is.

That's not true - if this grey level gets too close to white or black,
then the assembly drawing gets unintelligible. That's also why I am
asking. If I didn't care if the assembly drawing gets understood or not,
I would not ask. But I am displaying it on a webpage and I want the
people to be able to read it.

CL<