[time-nuts] OT: Hewlett Packard paint codes

[Neon John]

On Wed, 26 Dec 2007 18:35:26 -0500, Patrick <optomatic at rogers.com> wrote:

>I am missing the original post, hopefully I am on topic..
>
>I color match quite a bit. I refurbish lab instruments. I have a piece 
>of glass over top of my scanner platten. I mix the paint right on the 
>scanner and evaluate it with the GIMP. If you have not heard of it, it 
>is a free image manipulation program. You can click on a little dropper 
>icon inside the program and it will show you the RGB value for the small 
>region you clicked on.
>
>Hope this helps, If you need more details please feel free to ask-Patrick

I thought I was the only one to do that.  My method is easier than glass.  I use the
crystal-clear packing tape that is available from the office supply big box stores
and Rat Shack.  When carefully applied to the platen, it becomes totally transparent.
When the scan is finished, just rip it up and throw it away.

I bet Saran wrap would work equally well.  This does leave the problem of paints that
change colors when they dry.  The old "apply to substrate and dry with hair dryer"
method still applies.

Jack, back to your original problem, the trick to hitting the color spot-on after
only one or two tries is to use your scanner or even your digicam if you can keep the
lighting exactly the same, is to use it as a comparator.  Scan the original color and
save it.  Then generate output on your inkjet printer and scan that.  Look at the
difference in each color channel and modify your original artwork color accordingly.
Usually you can nail it after the second try.

This system doesn't rely on the accuracy of the monitor, printer or scanner, but only
its repeatability.  Repeatability is usually excellent, at least until you change
cartridges.

I haven't used this technique to duplicate colors on an instrument panel but I have
used it extensively for conventional graphics arts where I need to match the color on
a logo or whatnot.

RE: Gimp.  I wouldn't foist that crap off on my worst enemy.  Whomever conceived that
user interface had to be stoned.  Bad stoned.

John
--
John De Armond
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