Re: HP 5000 Inks and PMS 300
Re: HP 5000 Inks and PMS 300
- Subject: Re: HP 5000 Inks and PMS 300
- From: Roger Breton <email@hidden>
- Date: Fri, 23 May 2003 08:21:47 -0400
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I am having no luck making a print that matches PMS 300.
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My customer showed me a banner that they had printed that looks pretty
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close. It looks like a solvent inkjet banner or a 3m electrostatic. Very
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course dot patter.
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I've used Monaco proot and followed what instructions I can find for
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Onyx so I'm wondering.
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Is this color out of gamut for these inks or has somebody else been able
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to achive it?
Nick,
I think there is a way to determine "how much out-of-gamut" of your printer
color capabilities the PANTONE 300 color specification is. There are
probably many ways to go about it but here's two methods that come to mind:
First, if you have either X-Rite ColorShop or ProfileMakerPro ColorPicker,
it will be a snap. You just measure a "live" PMS 300 paper swatch of your
choice, with a supported spectrophotometer (remember to use D50/2), to
establish the Source CIE Lab color of 'PMS 300'. Once you have that number,
in CIE Lab units, select your ICC printer profile as Destination in one of
those two packages and, right away, you will have the best device
coordinates that match (absCol) your Source color, courtesy of ColorSync and
X-Rite or GMB. Now, along with the Device coordiinates, you will get (and
that's probably what matters most to you) -- get this -- the 'distance' of
these device coordinates represent relative to your starting PMS 300 CIE Lab
coordinates, in units of Delta E. Delta E is the Eucledian distance between
two colors in a 3-D geometrical space. The larger the Delta E value, the
worst your match is. A Delta E value under 10 and even 5 is quite
acceptable. Ideally, you'd want a Delta E below 3. But, just to give you an
idea of Delta E and PANTONE colors, I remember once printing posters on an
Encad inkjet printer for a local phone company retail outlets and, man,
there was no way we could get a better match for PMS ReflexBlue than 46
Delta E! That seems quite far and it is far. But remember (hope to provoke a
controversy, here) that the whole 1976 CIE Lab color space was fine tuned
for small color distance comparison. I think below 10 to 5. Very small
threshold visual differences. Above that, like in the 40 Delta E, I think
the Delta E metric of visual comparison is no longer of real value or at
least, it does not correspond well with actual, live observers observers of
perceived difference.
To come back to the subject at hand, here the second method. If you don't
have any of the above two packages, you could always use Photoshop to assist
you in quantifying the magnitude of Delta E. Start by setting your CMYK
Working Space as your printer profile, and AbsoluteColorimetric as your
default rendering intent under Conversion options, all in the Color Settings
Dialog box. Next, open the Color Picker. Key in your measured PMS Lab value.
Watch the CMYK value change as you input your measured PMS 300 Lab value.
Take note of those CMYK percentages. Now (I don't know of other ways to do
this) make a new CMYK document (still with your printer profile selected as
your CMYK Working space -- or you could Assign it to your document later)
and fill the Background with those same CMYK percentages. Pull up the Info
palette (F8) and watch the corresponding Lab value displayed when you hover
the document window with your favorite rodent. That's Photoshop using the
A2B1 table in your Assigned printer profile to calculate the Lab value.
At that point, you have all the information you need to calculate Delta E.
You have your starting CIE Lab values of your PMS 300 swatch, on the one
hand, and you have your 'matched' CMYK value in your printer profile color
space, expressed also in CIE Lab units, on the other hand. What comes next?
Well, a little of high school algebra. I think there are some free utilities
that can do this calculation for you (although I can't think of one right
now?). Or you could do a search in www.google.com under Delta E to find some
web pages that incorporate Delta E calculators online
(www.brucelindbloom.com, www.easyrgb.com, ...). Or you could always program
the equations yourself in a Microsoft Excel spreadsheet (most rewarding
option, no doubt). It is quite simple actually.
Regards,
Roger Breton
Laval, Canada
email@hidden
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