15 Nov
2004
15 Nov
'04
8:37 a.m.
In a message dated 11/15/04 11:03:11 AM Pacific Standard Time,
allain(a)panix.com writes:
BTW I have a 2nd hand Pantone guide right here, it reads out to "three
parts Pantone light red and 1/8 part ..." yadda
Well, that is how I mix the ink colors, by weight. Makes doing parts easy.
All major ink manufacturers sell Pantone colors so you can mix whatever color
you want.
The only inks sold in RGB type colors are multiple color process inks and to
blend them it is a process of screens and angles and you need to have multiple
passes through the press.
RGB does not lend itself to printing processes well. It is much cheaper to
print just one color.
John, since you have a Pantone book could you match the numbers to the DEC
stuff you have?
On each color swatch there should be a corresponding number. That is what is
important not the formulation.
You want to ignore the C and U letters as they refer to Coated and Uncoated,
more printing terms. (refers to whether you are printing a clear gloss coat on
top of the ink to get the glossy look or if printed on gloss stock.)
Somewhere DEC published the Pantone numbers in their documents they sent to
printers......
PS Printers are supposed to upgrade their $50 Pantone books every 6 months to
deal with fading, not many I know did that.
Paxton
Astoria, OR
15 Nov
15 Nov
10:19 a.m.
>>>> "Innfogra" == Innfogra
<Innfogra(a)aol.com> writes:
Innfogra> Somewhere DEC published the Pantone numbers in their
Innfogra> documents they sent to printers......
I know I saw a Pantone number the last time the corporate style
changed, the purple logo with the round dot on the i -- the one after
they kicked Ken out. For a lot of other things the internal documents
reference DEC internal color codes. For example, my Pro 380 spec says
the system box top/bottom are "68 Gray per DEC Std. 92". The LK201
keyboard is also that color.
So what you really need is a copy of DEC Std 92. Maybe someone on
this list has a copy. With luck, that will show the translations to
Pantone.
paul
6:17 p.m.
So what you really need is a copy of DEC Std 92.
That would be the ultimate, wouldn't it? DEC's own color
descriptions. If Curt.V can have all of Atari's corporate
documents then maybe someday someoneon the list could
find much of DEC's...
Why I like RGB, chapter 3... All of electronic graphics is based on it. If
it looks good on a TV, a computer monitor or anything from a Digicam,
then it has been RGB digitized at some point. A digital camera just
seems like a super convenient instantaneous color digitizer.
You don't mix pigments from Red Green and Blue but the result of any
pigment mix color can be communicated with RGB very well.
John A.
16 Nov
16 Nov
4:05 a.m.
>>>> "John" == John Allain
<allain(a)panix.com> writes:
John> Why I like RGB, chapter 3... All of electronic graphics is
John> based on it. If it looks good on a TV, a computer monitor or
John> anything from a Digicam, then it has been RGB digitized at some
John> point. A digital camera just seems like a super convenient
John> instantaneous color digitizer. You don't mix pigments from Red
John> Green and Blue but the result of any pigment mix color can be
John> communicated with RGB very well.
No, it can't.
There are colors that can be expressed in CMYK (four color "process"
printing) that cannot be expressed in RGB. There are colors that can
be made up in pigments that cannot be expressed in either.
People who do this stuff for a living talk of "gamut" -- the range of
colors that a particular system can describe. The RGB gamut and the
CMYK gamut largely overlap, but each has a range outside that of the
other. And there are other schemes (like Lab) that have yet a
different gamut. For that matter, there are printer with more than
four colors -- that is done to get a larger gamut.
You can read about this stuff in the Adobe Photoshop manual, or in
Electronic Publishing magazine, or in any decent textbook on color
printing. If you want to do professional grade color, you have to go
way beyond the narrow confines of thinking about color as simply RGB
color.
paul
5:31 a.m.
New subject: Color spaces (was DEC Colours)
A simple thing that I have used to help me out (in my work with cinema
projection and video editing) is:
RGB is a *transmissive* specification. It is used a lot where the light
from the image is being *generated* by that image...
like a CRT. It
*makes* the light.
CMYK is a *reflective* specification. It is used where light is bounced
off a colored surface, like a magazine page. As was pointed out, mostly
used in the printing and graphics arts.
And there are of course many other flavors and types of specs - and we
won't get into 'brightness' and all that entails...
So if you're trying to match paint - a 'reflective' specification would
be the most accurate, I would think.
Cheers
John
6:22 p.m.
New subject: Color spaces (was DEC Colours)
So if you're trying to match paint - a
'reflective' specification
would be the most accurate, I would think.
But not one as simple as CMYK.
Quite aside from the ways our eyes respond to light, in order to truly
match a given colour, you do need to match its reflectance spectrum at
least moderately well, otherwise the goodness of your match will depend
on the spectrum of the light you look at it under. (Just because two
lights look the same to your eyes does not mean they have even
approximately the same spectra! It just means that their spectra
dot-producted with your eyes' colour receptors' sensitivity spectra
come out fairly close to the same. Or whatever the term corresponding
to integral[x](A(x)*B(x)), the continuous analog of a dot product, is;
I can't remember offhand.)
And then there are issues of specularity and translucency and such.
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8:01 a.m.
If you want to do professional grade color, you have
to
go way beyond the narrow confines of thinking about color
as simply RGB color.
Implied from what you say there are scanners that _detect_
and record by methods other than by RGB. I haven't yet
seen any that do this, including many professional models.
Your words "way" or "narrow" I'd like to say I don't yet
follow,
without starting a flame war.
The RGB gamut and the CMYK gamut largely overlap,
So nobody's perfect but they can get along together.
John A.
9:15 a.m.
>>>> "John" == John Allain
<allain(a)panix.com> writes:
> If you want to do professional grade color, you
have to go way
> beyond the narrow confines of thinking about color as simply RGB
> color.
John> Implied from what you say there are scanners that _detect_ and
John> record by methods other than by RGB. I haven't yet seen any
John> that do this, including many professional models. Your words
John> "way" or "narrow" I'd like to say I don't yet
follow, without
John> starting a flame war.
Scanners use RGB -- which means that there are printed colors they
won't deal with.
I did not mean any insult by "narrow" -- only that there are many
color models, not just RGB, and RGB is neither the best nor the most
powerful model.
> The RGB gamut and the CMYK gamut largely overlap,
John> So nobody's perfect but they can get along together.
Only so long as you aren't doing work that requires accurate color in
a subtractive color environment, such as printing. Otherwise you'll
discover why Photoshop does CMYK, and why the manual chapter on that
topic is so long and complex.
paul
9:10 a.m.
At 11:17 PM 11/15/2004, John Allain wrote:
Why I like RGB, chapter 3... All of electronic
graphics is based on it. If
it looks good on a TV, a computer monitor or anything from a Digicam,
then it has been RGB digitized at some point. A digital camera just
seems like a super convenient instantaneous color digitizer.
RGB color is far more complex than that. What about the monitor
you're displaying it on? Consider the various phosphor blends
and the implicit or customizable settings of color temperature
in the monitor. RGB "White" isn't "white".
And gamma? If you've installed Adobe products, you may have their
gamma-tweaking tool inline in your display without realizing it.
Some video cards have their own gamma- and color-tweaking tools,
similarly adjusting your palette behind your (and your application's) back.
And digital cameras? You've got to be kidding. They're not
absolute devices by any means. Unless we're talking very high-end,
they're all tweaking the color balance in odd ways and you
probably aren't given any controls over it. Some begin to do
wacky things when the scene doesn't include a wide range of colors.
Reproducing a finish on metal or plastic must be even more
complicated than anything computer-based. Your perception of
the appearance of the finish is potentially dependent on all
sorts of specular and multi-layer-reflective and transmissive
colorings.
- John
17 Nov
17 Nov
11:31 a.m.
On Tue, 16 Nov 2004, John Foust wrote:
RGB color is far more complex than that. What about
the monitor
you're displaying it on? Consider the various phosphor blends
and the implicit or customizable settings of color temperature
in the monitor. RGB "White" isn't "white".
....
Reproducing a finish on metal or plastic must be even
more
complicated than anything computer-based. Your perception of
the appearance of the finish is potentially dependent on all
sorts of specular and multi-layer-reflective and transmissive
colorings.
Color is the same as food. Totally subjective!
And paints also derive effects -- often NOT subtle -- depending
on their depth, literally -- thickness; partially transmissive
partially reflective, and the texture changes the color and
the subjective emotional response to the whole thing.
Think "food".
But likely for squirting color on an old computer, "close is close enough".
18 Nov
18 Nov
9:16 a.m.
At 04:31 PM 11/17/2004, Tom Jennings wrote:
Color is the same as food. Totally subjective!
Think "food".
But likely for squirting color on an old computer, "close is close enough".
Exactly! How do you think I was able to spout off about
all the complications of color reproduction on computers,
if I wasn't an hourly consultant who gets paid to do so?
My ability to rant on any topic equals "food".
- John
19 Nov
19 Nov
6:15 a.m.
Color is the same as food. Totally subjective!
Gosh, will this thread never die?
Well, it's been interesting if overlong.
And paints also derive effects -- often NOT subtle --
depending on their depth, literally -- thickness; partially
Properly administered paint doesn't allow transmission
to the layer beneath it.
. . .
A conclusion seems to be that color perception (human or
machine) is not mathematically rigorous with respect to a true
chromatograph of a thing, and this spins out to complexity.
Meanwhile somebody in, say, L.A. wants the color of someone's
PDP-5 in Indiana.
I think unscrewing panels and taking them to Lowe's is better than
nothing, but that gets involved with some pretty uncalibrated machinery
and untrained individuals. And what if Guy#2 doesn't have a Lowes, etc.
Guess I'm just partial to what NASA does. Throw down a few reference
colors next to the thing, take a color photograph, and postprocess the
reference colors to what they should be. Although now I see that that is
like the problem of describing right and left to an alien. Where do you
get the reference colors in the first place? Guess one of us has to find
a vendor for the three swatches to mail to requesting parties.
John A.
11:09 a.m.
On Fri, 19 Nov 2004, John Allain wrote:
Guess I'm just partial to what NASA does. Throw
down a few reference
colors next to the thing, take a color photograph, and postprocess the
reference colors to what they should be. Although now I see that that is
like the problem of describing right and left to an alien. Where do you
get the reference colors in the first place?
Kodak.
18% ND gray card, (readily available from any TECHNICAL photo supply)
and you can use the color references in the Kodak
pocket dataguide (almost certainly discontinued?)
Guess one of us has to find
a vendor for the three swatches to mail to requesting parties.
12:04 p.m.
New subject: Colo[u]rs (was: DEC colours
On Fri, 19 Nov 2004, John Allain wrote:
Guess I'm just partial to what NASA does. Throw
down a few reference
colors next to the thing, take a color photograph, and postprocess the
reference colors to what they should be. Although now I see that that is
like the problem of describing right and left to an alien. Where do you
get the reference colors in the first place?
If you're trying to match COLOURs, try:
http://www.robertwhite.co.uk/colour%20management.htm
They have a bunch of stuff about colour management,
including grey cards.
If you're trying to match COLORs,
The THIRD edition (1966) of the "Kodak Color Dataguide"
has both gray scale and color control patches. (along with a
whole bunch of dedicated circular slide rules for things like
color correction with filter pack changes)
lower left of:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=29993&item=3…
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=378&item=690…
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=378&item=691…
not sure what is included in the FOURTH edition:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=67365&item=3…
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=378&item=691…
By the fifth edition (1975), they had dropped the color control
patches, but at least they kept the gray card.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=4685&item=38…
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=629&item=385…
--
Grumpy Ol' Fred cisin(a)xenosoft.com
12:27 p.m.
On Fri, 2004-11-19 at 09:15, John Allain wrote:
Huh? It's often done on purpose. You obviously haven't been to a
low-rider, hot-rod, or import-scene event [automobile]... :-) It's
practically a field of study, and it's certainly an industry.
And paints
also derive effects -- often NOT subtle --
depending on their depth, literally -- thickness; partially
Properly administered paint doesn't allow transmission
to the layer beneath it. Guess I'm just partial to what NASA does. Throw
down a few reference
colors next to the thing, take a color photograph, and postprocess the
reference colors to what they should be.
Umm, I'm not sure which NASA you're talking about, but the one that put
the earliest landers on Mars (single photo-diode mechanically scanned
camera with switchable filters to build a color image) has an entire
chapter in the coffeetable book about color subjectivity, and that there
is no "real" or "correct" color correction for earth vs. mars human
observers.
Where do you
get the reference colors in the first place? Guess one of us has to find
a vendor for the three swatches to mail to requesting parties.
Obviously the bottom line is "close enough". I can picture the paint
salesmammal sitting in the conf room with DEC marketing and engineers
looking at color swatches, NASA nowhere to be found. I seriously doubt
DEC gave a sh*t about color precision past some point, no manu does,
it's simply impractical, and no one but the back room geeks are looking
anyways, and they ain't writing the checks.
The places I've worked that painted objects did them in batches so at
least all the parts of an assembly match; an item made in year 0 and
year 0 + N may in fact not precisely match.
I think DEC was more concerned with the innards than the outwards.
3:04 p.m.
On Fri, 19 Nov 2004, John Allain wrote:
like the problem of describing right and left to an
alien. Where do you
get the reference colors in the first place? Guess one of us has to find
a vendor for the three swatches to mail to requesting parties.
And how do we know if DEC maintained the same reference colors throughout
their company history? And if so, perhaps they faded over time? Maybe
someone played shenanigans and switched them out with similar but
different colors at some point?
Who knows? Who cares! Color matching by eye is "good enough".
--
Sellam Ismail Vintage Computer Festival
------------------------------------------------------------------------------
International Man of Intrigue and Danger http://www.vintage.org
[ Old computing resources for business || Buy/Sell/Trade Vintage Computers ]
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3:21 p.m.
New subject: was: Re: DEC colours now: dead horse beaten into thin film
On Fri, 2004-11-19 at 18:04, Vintage Computer Festival wrote:
Who knows? Who cares! Color matching by eye is
"good enough".
The classic trick is to simply match a panel you have. For a good sample
of the "correct" (sic) color (colour) is to remove an escutcheon, or
flip a panel over, etc, to find paint that hasn't been exposed to
sunlight and/or coffee and match that.
Or squirt the whole thing wrinkle black. Everything looks good in
wrinkle black. No exceptions.
PS: You can get aerosol wrinkle black paint from www.eastwoodco.com.
Works great.
20 Nov
20 Nov
1:27 a.m.
New subject: was: Re: DEC colours now: dead horse beaten into thin film
On Fri, 2004-11-19 at 18:21 -0800, Tom Jennings wrote:
On Fri, 2004-11-19 at 18:04, Vintage Computer Festival
wrote:
What you need is a can of tartan paint... ;)
Who knows? Who cares! Color matching by eye is
"good enough".
The classic trick is to simply match a panel you have. For a good sample
of the "correct" (sic) color (colour) is to remove an escutcheon, or
flip a panel over, etc, to find paint that hasn't been exposed to
sunlight and/or coffee and match that.
Or squirt the whole thing wrinkle black. Everything looks good in
wrinkle black. No exceptions.
7:54 a.m.
New subject: was: Re: DEC colours now: dead horse beaten into thin film
On Sat, 2004-11-20 at 04:27, Jules Richardson wrote:
What you need is a can of tartan paint... ;)
!! you can buy spotted spray paint! Really, it appeared in a lot of
automobile trunks (boots). Basically it's little blobs of color in a
think aerosol black or grey. You can get it from J.C. Whitney, Eastwood,
etc.
What I want are plaid/tartan LEDs!
1:53 p.m.
New subject: was: Re: DEC colours now: dead horse beaten into thin film
On Saturday, November 20, 2004, at 10:54 AM, Tom Jennings wrote:
On Sat, 2004-11-20 at 04:27, Jules Richardson wrote:
Brand name: Zolatone <http://www.zolatone.com/products.html>
Jim
What you need is a can of tartan paint... ;)
!! you can buy spotted spray paint! Really, it appeared in a lot of
automobile trunks (boots). Basically it's little blobs of color in a
think aerosol black or grey. You can get it from J.C. Whitney,
Eastwood,
etc.
19 Nov
19 Nov
8:09 p.m.
And how do we know if DEC maintained the same
reference colors throughout
their company history? And if so, perhaps they faded over time? Maybe
someone played shenanigans and switched them out with similar but
different colors at some point?
Who knows? Who cares! Color matching by eye is "good enough".
I have to agree. Judging from all of DECstuff I have seen over the years,
it seems like the paintshop used whatever paint and schemes they felt like
on any given day.
Matching paint by eye really is not too hard - just be prepared to waste
some paint if a mix goes wrong, and experiment quite a bit...
William Donzelli
aw288(a)osfn.org
20 Nov
20 Nov
11:20 a.m.
>>>> "Vintage" == Vintage
Computer Festival <vcf(a)siconic.com> writes:
Vintage> On Fri, 19 Nov 2004, John Allain wrote:
> like the problem of describing right and left to
an alien. Where
> do you get the reference colors in the first place? Guess one of
> us has to find a vendor for the three swatches to mail to
> requesting parties.
Vintage> And how do we know if DEC maintained the same reference
Vintage> colors throughout their company history? And if so, perhaps
Vintage> they faded over time? Maybe someone played shenanigans and
Vintage> switched them out with similar but different colors at some
Vintage> point?
That's why people who care about color -- which is a lot of companies
and a lot of marketing people -- use the Pantone system or others like
it. That way you don't have to rely on faded samples or eyeball
matching. Tell a printer "the logo is Pantone 300" and you've
completely described what you're asking for.
Vintage> Who knows? Who cares! Color matching by eye is "good
Vintage> enough".
That depends on what business you're in.
paul
16 Nov
16 Nov
9:57 a.m.
John Allain wrote:
Why I like RGB, chapter 3... All of electronic
graphics is based on it. If
it looks good on a TV, a computer monitor or anything from a Digicam,
then it has been RGB digitized at some point. A digital camera just
seems like a super convenient instantaneous color digitizer.
You don't mix pigments from Red Green and Blue but the result of any
pigment mix color can be communicated with RGB very well.
Not unless you remeber about GAMMA correction.
7185
days inactive
7190
days old
23 comments
13 participants
participants (13)
-
allain＠panix.com -
aw288＠osfn.org -
bfranchuk＠jetnet.ab.ca -
cisin＠xenosoft.com -
Innfogra＠aol.com -
jfoust＠threedee.com -
jpl15＠panix.com -
jrasite＠eoni.com -
julesrichardsonuk＠yahoo.co.uk -
mouse＠Rodents.Montreal.QC.CA -
pkoning＠equallogic.com -
tomj＠wps.com -
vcf＠siconic.com