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In article <1992Dec28.000443.7228@hot.com> Robert_La_Ferla@hot.com writes:

   How does one create a gold tone in PostScript?  I realize that gold is  
   a metal and to create it you need to either render it or use a gold ink  
   but I'm looking for a simpler way to achieve the same effect.  I have  
   some artwork containing gold arcs and lines which will be printed on a  
   Canon CLC color laser printer.  Note that the artwork is pure  
   PostScript and was not created using an application.

   Is there a combination of CMYK values that approximates a gold  
   tone?  Is there a sample of a rendered gold image that I could use as  
   a fill pattern?  How would I do the latter?

   Robert La Ferla
   Hot Technologies

Gold is yellow plus the impression that the surface is
`metallic'/`specular', just as silver is white/grey plus an impression that
the surface is `metallic'/`specular'.  You cannot create the impression of a
metallic color merely by manipulating RGB or CMYK at a pixel. Context is
important. 

Surfaces with a specular component of reflection can sometimes be discerned
because of strong localized high-lights, particularly high-lights that
change in position as the viewer (or the light source) moves.  In other 
words, the way to get the impression of `gold' or `silver' is to create a
suitable spatial distribution of light and dark, preferrably with
a large dynamic range.  The best impression of `gold' would be in the
portrayal of a curved surface, where most of the surface is shown as black,
with one or more near parallel narrow streak of light yellow, with the
brightness varying within in the sreak from the edge towards the center.



Berthold K.P. Horn
Cambridge, Massachusetts, USA

In article <1992Dec28.000443.7228@hot.com> Robert_La_Ferla@hot.com writes:
>How does one create a gold tone in PostScript?  I realize that gold is  
>a metal and to create it you need to either render it or use a gold ink  
>but I'm looking for a simpler way to achieve the same effect.  I have  
>some artwork containing gold arcs and lines which will be printed on a  
>Canon CLC color laser printer.  Note that the artwork is pure  
>PostScript and was not created using an application.
>
>Is there a combination of CMYK values that approximates a gold  
>tone?  Is there a sample of a rendered gold image that I could use as  
>a fill pattern?  How would I do the latter?

I think your best bet would be to use a process like one of the
letraset plastic-laser bonding processes to get your gold tone. If you
are printing with a laser printer (even color), you can output the
gold layer artwork first, then melt opaque metallic gold toner into
the black, covering it over, and then run it back through your printer
for the other layers. I can't remember the name of the process (there
are at least three or four in the market in the U.S.), in French or
English, which does it, and you have your choice of a spectrum of 100
Pantone tints, including shiny metallic gold, silver, copper, green,
purple, red, blue, and matte gold, silver ('aluminum'), and a few
other metallics. They work spectacularly well - it really does look
like gold-embossing. If all you are making is a maquette, then this is
perfect. If you want production, you have to print with gold ink,
period, the effect production is too expensive and tiresome to do. If
you want 'gold' look then balance to a pantone gold, choose where you
want a pseudo-highlight to be, and do a fountain fill to from 50/50
tint/black to 100% white at that point, then fill back to 50/50
goldtint/black. It won't look like gold, but like 'metallic yellow'.

-- 
| Le Jojo: Fresh 'n' Clean, speaking out to the way you want to live
| today; American - All American; doing, a bit so, and even more so.

Another way to get Gold is to 
	1) print the area you want to be gold, but use all black
	2) attach special gold foil to your page
	3) run the page thru your Laser printer without printing anything.
	4) remove the gold foil. The gold will adhear to the black ink
	   of your page when it passed thru the fuser.
Paper Direct (1-800-272-7377) sells the gold foil along with several
other colors. 
--
Bruce Barnett <barnett@crd.ge.com> uunet!crdgw1!barnett

In article <1992Dec28.000443.7228@hot.com> Robert_La_Ferla@hot.com writes:
>How does one create a gold tone in PostScript?  I realize that gold is  
>a metal and to create it you need to either render it or use a gold ink  
>but I'm looking for a simpler way to achieve the same effect....
>
>Is there a combination of CMYK values that approximates a gold  
>tone? 

There have been a number of replies pointing out that it's just not
possible to achieve exactly the right effect. However, for those
who do not want the expense of sticking gold leaf onto their pictures,
and are prepared to accept a crude aproximation try an RGB of
238 221 40 (where 255 is the max).

This works quite well on a Tektronix Phaser Postscript printer. This has the
advantage that the wax gives a slight sheen. The result is not unreasonable
on other devices, including colour screens. If you apply the criterion of
displaying the result to the person in the street and asking them what colour
it is - if 9 out of 10 say gold, then it will do. I haven't done exactly
that, but when I used these values for the gold part of the University crest
most who saw it thought it was OK. (I know they were _expecting_ to see
gold, and that no doubt influenced them.)

I would be interested to know what other values people have used.

My values were obtained by simple iteration around integer RGB values
in the range 0 to 255, one idle weekend when we had a Tektronix Phaser on
trial. My partner and I just compared the result, by eye, with the large
area of gold-coloured ink on a common UK cigarette packet! (No flames
for my anti-social smoking habit please :-)