Re: Fwd: [Gnuplot-developers] [ gnuplot-Patches-1651015 ] Cairo-based PDF terminal

[Petr M. <mi...@ph...>]

> %% Boolean flag Color (user-editable) used to toggle palette;
> %% Switch between rgb color and grayscale using ntsc conversion
> \C  {Color {setrgbcolor} {ntsc setgray} ifelse} def

ntsc =3D Never The Same Color? ... here Gray ...

Given an RGB, you can never get the original gray value, because the mappin=
g=20
depends on the colormap: gray =3D> (R(gray), G(gray), B(gray))

> >   - possibility to change the color palette
>=20
> By editing the PostScript file?  That sounds like a very unusual
> thing to do.  Can you give an example?

Yes, unusual, but feasible.=20

> > > I'm cc'ing this to Petr, who may want to comment on whether
> > > there are cases where weak optimization (factor of 2 at best)
> > > is still useful.=20
> >=20
> > It is of factor 3:
> > =09.123
> > =09.123 .123 .123
> > thus a lot of KB's more to add into the file or (LaTeX) paper.
>=20
> I think it's a factor of slightly less than 2:

So it is great, isn't it? It saves a lot of disk space for large maps.
(Please don't claim that *nowadays* the disk space is cheap.)

> > No, pdf is not intended to be edited.
>=20
> PDF is mostly just marked-up PostScript which is then compressed.
> Any feature which is useful in PostScript should also be available
> in PDF.

Unless some postscript programming, like ifelse ... ?

> Even aside from Timoth=C3=A9e's new pdf driver, wouldn't it be a good
> idea to offer the same user-editable flags at the start of gnuplot's
> PDF output that we offer for the PostScript output?  That would give
> the user the same ability to tweak the *.pdf file that they already
> have for the *.ps files.

How would he tweak them? A javascript?
Have you seen any example of such a pdf gray/color file with a switch?

---
PM