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1. Re: Lighting temperature considerations for print evaluation?
Larry Tseng Jul 4, 2010 9:26 PM (in response to RichPate)You could try setting your monitor to around 3500K while at the same time
illuminate your work area and surroundings with 3500K lamps. This should
allow you can stay adapted to this white as you proof and go about your
photoshop work. If the surface illumination of your proofs are around 250
lux (museum level of lighting), then an appropriate luminance setting for
the monitor would be around 80 cd/m2.
I recently started taking this rather unconventional approach after
discovering the relationship between the level of illuminance and color
temperature in this article:
http://www.solux.net/cgi-bin/tlistore/infopages/eyes-response.html
According to my interpretation of the Kruithof Curve, a doubling of the
illuminance from 250 lux to 500 lux would require the color temperature to
be set at 3900K to maintain the same color balance (160 cd/m2 on the
monitor). At 6500K, we'd be illuminating proofs in direct sunlight to
maintain balance!
It's not as straight forward as this in actuality, but I'm encouraged by the
3500K - 250 lux - 80 cd/m2 results, and would be interested to hear what you
find if you should give it a try.
Cheers,
Larry
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2. Re: Lighting temperature considerations for print evaluation?
RichPate Jul 5, 2010 3:09 PM (in response to Larry Tseng)Thanks Larry. Very interesting article. Andrew Rodney and others over at the Photo.net Digital Darkroom Forum have weighed in on the article and my original question.
I am intrigued with the approach you are taking. I am leaning towards that approach also, ever since I heard that John Paul Caponigro recommends evaluating prints under 3500K (of common display lighting) rather than the holy grail standard of D50 or D65. I can see how bright lighting in the print viewing area would be helpful for evaluating sharpness or printing imperfections, but for color, brightness and contrast it doesn't make sense in the real world where our prints are displayed and sold.
Unfortunately, I can't find anything more on JPC's website about the best way for doing this in a color managed workflow. That info is probably reserved for his fine art printing seminars.
Could you please explain "lux" to me and the 250 lux figure you came up with? Is this something I can use the spot meter on my DSLR to measure? Is it similar to cd/m2? I'm an artist/photographer who is rather challenged at the technical aspects of color management.
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3. Re: Lighting temperature considerations for print evaluation?
Larry Tseng Jul 5, 2010 5:41 PM (in response to RichPate)Hi Richard,
Thanks for mentioning the thread over at photo.net.
This from Wikipedia: "Illuminance is a measure of the intensity of
illumination on a surface." My cheap (but good enough for my purposes) lux
meter measures the intensity in lux units.
Also from Wikipedia: "Luminance is often used to characterize emission of
reflection from flat, diffuse surfaces." The measurement unit is candella
per square meter (cd/m2).
I have been using this formula to relate the two:
Luminance = (Illuminance x Reflectance Factor)/PI
So suppose the glossy paper that you are using has a reflectance factor of
0.85 (1.0 = all light reflected back from the paper), and you measure 250
lux of illumination on the surface of the print, then the luminance of paper
white will approximate (250 x 0.85) / 3.1416 = 67 cd/m2. This would also be
what I'd target for monitor white luminance.
You can obviously work the numbers the other way, starting with 80 cd/m2 for
the monitor. Then a luminance match would occur if you have (80 x 3.1416) /
0.85, or 296 lux, playing on the surface of the print.
I don't think that you need to be as precise as the numbers would suggest. I
also think that you'll easily get the hang of it if you have a quick way to
get a lux reading.
This should be interesting...
Larry
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4. Re: Lighting temperature considerations for print evaluation?
RichPate Jul 6, 2010 9:47 AM (in response to Larry Tseng)Yes, indeed, very interesting stuff -- and so easy to get absorbed into the details of "Light" science. So much to learn and so little time (and money).
So on that note, Larry, I have taken your recommendation and turned the brightness setting of my new 24" Dell U2410 down to 10% (on a scale of 0 to 100%), which according to a test report measurement I read, yields a luminance of about 100 cd/m2 (down from the 190 cd/m2 default). I have no way to measure this for sure. But, Wow, what a difference, and my prints no longer look so dull by comparison.
Now it's time to calibrate my monitor with a Spyder2Pro. Do you just start to calibrate the monitor with it manually set at this lowered luminance and ignore any luminance settings recommended in the calibration process?
Seems like I remember that all the calibration results I have gotten on other LCD monitors in the past have turned out with too bright a luminance. That may be due to the ColorVision folks, who make my colorimeter, who say to set the LCD monitor at its brightest setting (100%) before you begin calibrating, and set the white point to 6500K.
What procedure do you use to color calibrate your monitor at these low luminance levels? Thanks again.
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5. Re: Lighting temperature considerations for print evaluation?
Larry Tseng Jul 6, 2010 12:17 PM (in response to RichPate)I'm not familiar with either Spyder2Pro or your Dell, but yes, you can start
your calibration with the lowered brightness to see where it takes you.
Basically you should try to do as much as possible via the manual controls
to reach your target of 3500K - 80 cd/m2 - gamma 2.2. If you don't do this,
your calibration software will be forced to apply large levels/curves
adjustments to your computer's video LUT to try to reach the aim points.
So, for example, without the manual brightness adjustment, a roughly 50%
drop in intensity would have to be applied to bring 190 cd/m2 down to 100
cd/m2 in your example, with a corresponding loss in tonal gradations.
Imagine working with the Levels tool in Photoshop where the maximum Output
is fixed at level 128 instead of level 255.
I would expect this process to take several interations/multiple tries.
Thinking on it, you do realize that this is an experiment, right?
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6. Re: Lighting temperature considerations for print evaluation?
p_d_f Jul 7, 2010 12:09 AM (in response to RichPate)Wouldn't another way to approach the situation be to make custom print profiles that take into account the print illumination when making the profile. I know that ProfileMaker allows profiles to be made with those variables. Then you shouldn't have to fudge your overall calibration around that much and use the proper profile in the proofing path to simulate your output. I suppose that if you don't mind having a screen set at an abnormally low color temp, the approaches outlined might work, but only if you have just one type of print viewing conditions to deal with.
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7. Re: Lighting temperature considerations for print evaluation?
Larry Tseng Jul 7, 2010 8:30 AM (in response to p_d_f)Yep, I think you are at least one step ahead of me.
Because I had been working in a comfortable "everything-D50 environment," it
hadn't occurred to me that an illuminant mismatch existed between my usual
D50-illuminated sources and my 3500K Solux viewing environment. So I began
to rectify this yesterday by measuring the spectral characteristics of my
viewing station with iShare, then used that to create a new printer profile
in ProfileMaker 5. Haven't had a chance to test it out yet, but I do expect
my print to screen match to improve. I can probably eak out an even better
match by using the same illuminant for my monitor profile.
I guess the larger question that you pose is this: can one prepare images
under one color temperature and produce prints suitable for viewing under a
different temperature simply by reprinting using different printer profiles
that are modified for the new environment.
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8. Re: Lighting temperature considerations for print evaluation?
p_d_f Jul 7, 2010 11:47 PM (in response to Larry Tseng)"I guess the larger question that you pose is this: can one prepare images
under one color temperature and produce prints suitable for viewing under a
different temperature simply by reprinting using different printer profiles
that are modified for the new environment."
I'm pretty sure that's the whole reason that capability was incorporated into ProfileMaker, and on a certain level, it's the same principal of ICC profile based output targeting in general: Prep file under fixed calibrated standard, apply output profile, tweak to suit output nuances, print. I would be more worried about what the file looked like on screen if that screen was calibrated as warm as 3500K. It just seems like it would be harder to decide pixel values under those conditions than to rely on good profiles to both preview and provide translation to output space.
I can't remember off the top of my head how many different color options are included in ProfileMaker, but in my testing, there was very little difference between the various D-50 ish options and since I only have a Spectrolino, I don't think I can measure a viewing light situation. I'll be interested in hearing how this works for you. It may force me to buy an iOne at some point, but I have other spending priorities at the moment.
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9. Re: Lighting temperature considerations for print evaluation?
Larry Tseng Jul 8, 2010 8:55 AM (in response to p_d_f)p_d_f,
Thanks for your comments.
I would be more worried about what the file looked like on screen
if that screen was calibrated as warm as 3500K. It just seems like
it would be harder to decide pixel values under those conditions than
to rely on good profiles to both preview and provide translation to
output space.
Surprisingly, you work as you normally would once fully adapted to 3500K.
No mental translation of colors is needed since monitor white is perceived
as neutral white in this state.
In an earlier setup, I had a lot of difficulty convincing myself that my
very yellow monitor is actually white. There were just too many visual cues
in my office that pointed in the other direction, e.g., light leaking
through a set of blinds behind the monitor, general office lighting outside
my doorway that I would see when when talking to a coworker, and so on.
The problem went away once I relocated to the office basement and equipped
it with 3500K lamps for proofing as well as general illumination. Here I
move about freely printing, proofing, and adjusting, without having to
re-adapt.
The first time that I resurface from the basement after a long work session,
I was surprised how blue and clinical the office surroundings and scenery
outside the windows looked.
I'll post any new developments here.
Cheers,
Larry
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10. Re: Lighting temperature considerations for print evaluation?
jpcaponigro Jul 10, 2010 10:59 AM (in response to RichPate)Hi!
The reason I recommend 3500K is it simulates gallery and museum viewing light (halogen - varying between 3300K and 3800K with varying amounts of daylight depending on time of day). (Most homes use tungsten - 2800K with varying amounts of daylight depending on time of day.) A majority of viewers prefer to live in and view images in warmer light, like 3500K. It's not as accurate but customer satisfaction goes up. 3500K is a real world practical recommendation. If you use 3500K there will be a mismatch between your softproof and your print if you use an ICC profile built for 5000K, which most are (but this may begin to change soon - I'm hoping vieiwing light temperature specific profiles start to take off). Your print will look warmer than expected. Expect to make a standard cooling adjustment to your images before printing. Or, build a light temperature specific profile. (Note, if you balance you prints for 5000K in a lab and then exhibit those prints in real world situations, they will almost always look too warm - unless you change the exhibition light to 5000K.)
5000K is the industry standard. Use it for a viewing light and you'll get the best match to a softproofed image on screen, if like 99% of users you're using a 5000K profile. For best results use a full spectrum bulb like Solux (for all light temperatures) to avoid non-uniform saturation distortions of specific hues. Cool white flourescent bulbs make blues appear more saturated and reds less saturated. Full spectrum bulbs don't distort color appearance. 5000K is a good standard. It renders whites more neutral than 3500K (yellower). If you use a 5000K standard take steps to ensure that your prints are viewed under 5000K light in the real world (change bulbs in exhibitions spaces and give bulbs away when you sell prints) - often this isn't practical.
If you're making prints for display in non-standard areas - outdoors or atriums with a lot of ambient light or spaces with unusual lighting like neon or sodium - compensate appropriately.
Theoretically, 5000K is correct.
Practically, balance your prints for the final viewing light.
I hope this helps.
There are many more resources on my website.
http://www.johnpaulcaponigro.com/downloads/technique/technique.php
And in my DVDs.
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11. Re: Lighting temperature considerations for print evaluation?
thedigitaldog Jul 11, 2010 9:18 AM (in response to RichPate)RichPate wrote:
Thanks Larry. Very interesting article. Andrew Rodney and others over at the Photo.net Digital Darkroom Forum have weighed in on the article and my original question.
Its all quite simple really, and the long posts over on PhotoNet seem to be making this all far more complex than it needs to be.
5000K (or for that matter any value provided in Kelvin) is a range of colors. This is why its useful when expressing a kelvin value to use Correlated Color Temperature (CCT) prior to any value. Many different colors correlate to the same numeric value. One light source that is said to be 5000K could produce a different color than another light source said to be 5000K. A Standard Illuminant, like D50 is at least a definition of a fixed, single color based on its Spectral Power Distribution(SPD). That doesn’t mean that someone specifying a light source or calibrating a display to D50 results in the product producing D50. In a prefect world this should be the case. Another issue is one can take the same instrument and two different calibration products and ask for D50 or worse (because its somewhat ambiguous, 5000K), calibrate the display and get differing results.
Figure out what light source you will use to view the prints next to the display. Many are recommending CCT 3500K Solux bulbs. This can be used to view prints away from the display environment but that isn’t a rigid requirement. Your eyes will adapt to the conditions under which you view your prints either next to the display or 10 miles away. The goal is WYSIWYG in terms of the print and the display. That means you have to have this display in the environment where you view the prints. It means you have to calibrate the display and control the viewing environment of the print next to the display. If you select CCT 3500K Solux (or a Fluorescent GTI booth etc), you now need to set the calibration target values of your software for a display calibration and the resulting display profile. What are the right settings? One would assume that you would ask for a CCT 3500K white point in the software. That’s not likely going to work, again due to the CCT values here, the differences between the Fluorescent light (or maybe LED) display backlight and so forth. The right values are those that produce a visual match, period!
The value may be D50 on an NEC SpectraView using their software. It might be CCT 6000K using EyeOne Match. It might be D55 using another type of display. Your Mileage May Vary. You have to enter various values until you result in a visual match. This is a reason why the better calibration products for displays allow one to insert an X/Y chromaticity value instead of relying just on a CCT or standard illuminant value.
To the same degree, the backlight intensity, specified in cd/m2 needs to be adjusted to taste. Again, YMMV. How bright is the light illuminating the print? Can you control this either using a dimmer (not useful for Solux, it alters its color) or by moving the light closer or farther from the print. The dreaded “my prints are too dark” issue is 98 out of 100 times, a severe disconnect between the intensity of the viewing booth and the target calibration of the display backlight. These people generally need to dial down the display luminance and/or raise the viewing booth intensity to result in a visual match.
Getting a CCT 3400K Solux and a decent display, driven with decent software to produce a match is totally possible and many people do this all the time. The same could be said of a good GTI or Just Normlitch (or similar) Fluorescent booth (although there are issues with Fluorescent lighting and interaction with OBAs in some papers).
Why CCT 34000K Solux? Simple, they look better. While a CCT 4700K bulb (and its new cousin the 5000K bulb) in theory should be a “better match” because they are numerically closer to the so called 5000K standard (its really D50), due to these values being not very reliable descriptors of the color, the cooler bulbs don’t produce as pleasing effect. If you go into galleries with Solux bulbs, especially those who have tested several different flavors of CCT values, almost all select the 3500K Solux. No reason not to use that for your custom made viewing booth. And as I said, if you then get your visual match between booth and display, take the print into the kitchen, outside, to another gallery etc, your eyes will adapt to the new white point, assuming its not some weird-*** illuminant (metal halide mixed with daylight etc). You will like the appearance of the prints when you move them away from this display to viewing booth environment.
Of course, all this begs for good displays, using good instrumenting and software. You may wish to produce multiple calibration targets and resulting profiles for differing papers (contrast ratio settings). Or you may be working with Solux and Fluorescent booths because customers are using the later and you need to collaborate with them. Mucking around with the display OSD’s to produce the ideal cd/m2 and white point is not the best approach, better are “smart monitors” that do all this internally in high bit (the NEC SpectraView II line comes to mind). Effective soft proofing is only as strong as the weakest link in the chain. But it is possible and achieved every day by many.
Could you please explain "lux" to me and the 250 lux figure you came up with? Is this something I can use the spot meter on my DSLR to measure? Is it similar to cd/m2? I'm an artist/photographer who is rather challenged at the technical aspects of color management.
Lux like cd/m2 is just a unit of measurement of light intensity. Lower for the ambient conditions is always better. It can’t be too low (it can be too high). Any ambient light in the environment will have an effect on the blackest black the display can produce so again, lower is better. You want the brightest and darkest object you view to be the display. When you are editing, the viewing booth can be off but at some point, you’ll want to view print and display. Here you need to correctly setup the soft proof (unfortunately that today means Photoshop) with the simulate check boxes on, with the image in full screen mode. No palettes, no UI elements which can’t undergo the white simulation. Black bkgnd for the image (hit tab key, F key until all you see is the image on screen, filling the screen or as close to the size of the print as possible).
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12. Re: Lighting temperature considerations for print evaluation?
thedigitaldog Jul 11, 2010 9:21 AM (in response to p_d_f)p_d_f wrote:
Wouldn't another way to approach the situation be to make custom print profiles that take into account the print illumination when making the profile. I know that ProfileMaker allows profiles to be made with those variables.
Yes, it is a useful function. It helps but its not a huge difference. That is, nailing the target calibration of the display and the print to result in a match will be 90% of the work. Making a profile whereby you measure that illuminant with say an EyeOne Pro, save out a CFX file and load that into ProfileMaker Pro will buy you maybe another 2-3%. Again, it helps but its not the bigger issue here in getting a match.
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13. Re: Lighting temperature considerations for print evaluation?
Tim Lookingbill Jul 11, 2010 10:44 AM (in response to jpcaponigro)What colors do you see need to be edited to correct for the mismatches caused by the Solux 3500K light?
Does it involve a lot of time editing for every possible color mismatch seeing how our eyes adapt the longer we gaze at non-neutral looking light?
Is it worth the effort?
How would we know if the color that's off is just our eyes adapting?
Will a person viewing this custom edited image in a gallery see something different according to the nature of their eyes?
Since a display isn't a Solux 3500K halogen bulb but backlit by fluorescent or LED, will the calibration software adjust the affects of the displays inherent non-uniform spectral distribution characteristics to mimic the HSL errors introduced by the Solux?
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14. Re: Lighting temperature considerations for print evaluation?
thedigitaldog Jul 11, 2010 12:31 PM (in response to Tim Lookingbill)None, there is no missmach
No
Yes
Doesn't matter
No
Doesn't matter
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15. Re: Lighting temperature considerations for print evaluation?
Larry Tseng Jul 11, 2010 4:43 PM (in response to thedigitaldog) -
16. Re: Lighting temperature considerations for print evaluation?
Larry Tseng Jul 11, 2010 4:49 PM (in response to thedigitaldog)thedigitaldog wrote:
p_d_f wrote:
Wouldn't another way to approach the situation be to make custom print profiles that take into account the print illumination when making the profile. I know that ProfileMaker allows profiles to be made with those variables.
Yes, it is a useful function. It helps but its not a huge difference. That is, nailing the target calibration of the display and the print to result in a match will be 90% of the work. Making a profile whereby you measure that illuminant with say an EyeOne Pro, save out a CFX file and load that into ProfileMaker Pro will buy you maybe another 2-3%. Again, it helps but its not the bigger issue here in getting a match.
Agreed. Small effect. And Andrew said the rest. Regarding posting any new developments here, I decided to start a new thread since the topic that I have in mind is only tangentially related to this one.
(Please excuse my email reply that didn't quite make intact.)
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17. Re: Lighting temperature considerations for print evaluation?
jpcaponigro Jul 12, 2010 9:27 AM (in response to thedigitaldog)Go Andrew! Three cheers! Hurrah! Hurrah! Hurrah!
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18. Re: Lighting temperature considerations for print evaluation?
Tim Lookingbill Jul 12, 2010 10:14 PM (in response to jpcaponigro)Geez! John. That's brilliant.
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19. Re: Lighting temperature considerations for print evaluation?
RichPate Jul 15, 2010 8:09 AM (in response to jpcaponigro)jpcaponigro wrote:
Go Andrew! Three cheers! Hurrah! Hurrah! Hurrah!
Yes, indeed. Thanks John Paul, Andrew, Larry, p_d_f, and Tim.
VERY helpful information here that has helped me, and I'm sure many others, set up a color management system that is better tailored to the lighting of the final print display environment.
Now to decide how to come up with a Munsell N8 neutral gray paint for my print viewing area and studio. But that can be for another thread.
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21. Re: Lighting temperature considerations for print evaluation?
thedigitaldog Jul 15, 2010 12:33 PM (in response to Gyno-jiz)Here’s a list of other possibilities for the paint. Its from a post to the ColorSync list, Danny gathered up all the possibilities based on various treads. There is no guarantee that the paints specified are still on the market.
Hello Steve,
Here is a compendium of answers. The Pittsburg recipe is in there.
Danny Pascale
dpascale@babelcolor.com
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From: Chris Murphy <lists@colorremedies.com>
To: coloru <colorsync-users@lists.apple.com>
SendDate: Tue, 19 Dec 2006 14:15:05 -0500
Subject: gray paint
Sherwin-Williams 2129 Zircom is apparently no longer available and seemed to be one of the more popular formulations for gray wall paint. Does anyone have a suggestion for something else?
Chris Murphy
Color Remedies (TM)
New York, NY
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From: Robin Myers <robin@rmimaging.com>
To: colorsync-users@lists.apple.com
SendDate: Tue, 19 Dec 2006 13:50:10 -0800
Subject: Re: gray paint
After checking my spectral database, I find the following paints which may be useful:
Glidden
00NN 62/000
00NN 53/000
00NN 45/000
Robin Myers
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From: Bret Hesler <bhesler@thebault.com>
To: <colorsync-users@lists.apple.com>
SendDate: Tue, 19 Dec 2006 15:51:13 -0500
Subject: Re: Gray paint
This is from a document I downloaded from Gretag Macbeth
(SPL tech bulletin logo 1203.doc):
Surround Recommendations:
N-7 Paint Formula
Recommended for interior walls
Behr Paint available at Home Depot
Base Premium Plus Interior Flat (1500A) pastel base
Formula
Colorant OZ 48 96
B Lamp black 0 15 1
I Brown oxide 0 3 1
T Medium Yellow 0 1 1
Recommended for the metal walls of a SpectraLight booth
Polyurethane
Sherwin Williams
Tel: 201-933-3800
Formula F63VXA3082-4350
Bret Hesler
L.P. Thebault Company
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From: "Calabria, Anthony" <Anthony.Calabria@Benjaminmoore.com>
To: <lists@colorremedies.com>
CC: colorsync-users@lists.apple.com
SendDate: Tue, 19 Dec 2006 16:01:08 -0500
Subject: RE: gray paint (Chris Murphy)
Chris,
Try either Benjamin Moore 1459 (Metro Gray) or 2112-60 (Cement Gray) in
product 215 (flat finish). Both have a CIE L* around 80 and are quite
neutral.
Anthony
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From: Daniel Vezina <daniel_v@videotron.ca>
To: "colorsync-users@lists.apple.com" <colorsync-users@lists.apple.com>
SendDate: Wed, 20 Dec 2006 23:02:59 -0500
Subject: Re:Gray Paint
GretaMacbeth published a recipe a few years ago for those that want to make
viewing booth. This gray is similar to what you can find in small GTI
viewing booth. Probably not as perfect as you wish but maybe it's a good
starting point, especially for large surface if you're tight on the budget.
I used it for my own studio and I find it OK (but you may have more strict
requirements than me).
The recipe is this one:
Brand: Pittsburgh Paint
Serie: Manor Hall
Recipe :
B1Y30
C26
M16
I went to a Pittsburgh dealer and give the recipe to them. They mixed it for
me with this info. It is not a std Pittsburgh color, it is a custom mix from
Greta. They choose the right base to mix for me. I think they used a neutral
base for pastel colors.
Good luck!
Daniel Vezina
Technical Director
www.numart.ca
Les productions Numart Inc.
PQ, Canada
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From: "Calabria, Anthony" <Anthony.Calabria@Benjaminmoore.com>
To: <colorsync-users@lists.apple.com>
SendDate: Thu, 21 Dec 2006 15:40:07 -0500
Subject: RE: gray paint (Chris Murphy)
Chris,
Try either Benjamin Moore 1459 (Metro Gray) or 2112-60 (Cement Gray) in
product 215 (flat finish). Both have a CIE L* around 80 and are quite
neutral.
Anthony
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From: PixelPusherz <pixelpusherz@gmail.com>
To: colorsync-users@lists.apple.com
SendDate: Tue, 19 Dec 2006 18:40:30 -0500
Subject: Re: gray paint
Yes, I had this same problem when I requested it (and its Zircon, not Zircom). But the resourceful chap I spoke with managed to look up the formula, even though it was not a current color. Here's the formula that got printed on the sticker I have:
Colorant 32 64 128
R2 Maroon 1 - 1
Y3 Deep Gold 3 1 1
B1 Black 15 - -
SInce I don't mix paint for a living I have no idea what these numbers mean, but the color is quite pleasing! Otherwise I'd just take a ColorChecker chart to a paint store (one that real professional painters use) and have them match one of the neutral patches on the bottom. The Zircon is pretty damn close to Munsell N8. If I had to do it again I probably would have chosen something closer to N6.5 or N5.
Hope this helps!
Eric Bullock -
22. Re: Lighting temperature considerations for print evaluation?
Tai Lao Jul 15, 2010 3:04 PM (in response to thedigitaldog)It's great to have you participating here again, Mr. Rodney.
Thank you for that very valuable information.
Wo Tai Lao Le
我太老了




