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Author Topic: Colorchecker Passport and Fine Art Reproduction  (Read 17521 times)
WombatHorror
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« Reply #40 on: January 18, 2012, 08:36:32 PM »
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Not really. See:http://www.color.org/ICC_white_paper_20_Digital_photography_color_management_basics.pdf

but in his case the goal IS to get accurate reproduction and in his sort of scenario you do not have any of the stuff that paper there goes on about, he does want direct colorimetric matching (when it comes to his having to make prints though, if he does, then it gets tricky since you will have to squeeze the gamut onto his printers and there are many methods and true testing is time consuming and tricky and not much work has compared different methods and various method can work better at various times and then his viewers need to view the print under expected conditions and not having just stared at a green light for an hour or anything weird hah, etc.
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WombatHorror
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« Reply #41 on: January 18, 2012, 08:41:41 PM »
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I do fine art reproduction for a living and have found that the Passport profiles are a little too vivid, plus the 24 samples are not very evenly distributed in the color spectrum, so there are some pretty big holes that the software has to guess at (I know MacBeth's motivation for choosing the colors they chose, but it doesn't help me much).  I've had better luck with the Qp card, and their free Qpcalibration software.  The 35 colors in the Qp chart are more helpful for art reproduction purposes, at least for me, and I find that I start with a closer approximation using that system than what I was using with a MacBeth chart and DNGProfiler (which I liked better than the Passport software).  Photo printing is so much easier to do than art reproduction, just because the standards are so high when side by side comparisons are as easy as they are with art.

I will have a look at the Qp thingy. It certainly doesn't hurt to have more patches, even 35 is not so many really. And speaking of that yeah I wonder if 35 is enough to be worth the upgrade price. It maybe better to go at least CC SG.

« Last Edit: January 18, 2012, 09:12:03 PM by LarryBaum » Logged
WombatHorror
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« Reply #42 on: January 18, 2012, 09:11:20 PM »
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2. Shoot RAW but do not use ACR for RAW conversion it does not have a wide enough gamut to accommodate all the colours you may need to preserve, it is also built for speed not accuracy detail smoothing and demosaic errors will appear.  I use a heavily modified version of Rawtherapee that includes slow but accurate demosaicing my own input and output spaces tuned to fine art and is floating point for greater accuracy and detail.

How does ACR not have a wide enough gamut? You can set it to ProPhotoRGB 16bit for final result and I think they present using Melissa (ProPhotoRGB primaries with TRC of gamma 2.2) while using ProPhotoRGB primaries with TRC gamma 1 while calculating so various slider work better applied there than after conversion to gamma 2.2 or sRGB TRC or what not).
« Last Edit: January 18, 2012, 09:24:34 PM by LarryBaum » Logged
Ellis Vener
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« Reply #43 on: January 21, 2012, 06:16:22 AM »
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Roscolo:

What lighting are you evaluating the print and the original art work with?
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Ellis Vener
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bill t.
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« Reply #44 on: January 23, 2012, 01:03:51 PM »
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This is where we were not long ago, so everybody cheer up.

Check the non-linear, marvelously crossed-over gray scale and the rich play of color casts across the matte surface.  Back in the day there were a lot more just like this, and NO PHOTOSHOP and NO PROFILES.  You kids today have it too easy.

Roscolo, let us know if you try that QP thing, or if you find some other repro-magic.

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Colorwave
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« Reply #45 on: January 23, 2012, 01:54:29 PM »
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LOL, Bill.  I sometimes get 4" x 5" chromes from clients that were shot by someone who got plenty of mileage from his color charts.  The first color swatch on the left is labeled, Blue, BTW.  Nice separation between the Magenta and Red swatches, too.  (Note to self:  don't store any color charts in a window sill or on the dash of my car)
« Last Edit: January 23, 2012, 01:56:23 PM by Colorwave » Logged

yannb
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« Reply #46 on: January 23, 2012, 05:37:35 PM »
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Hello,

For a demo of color reproduction using a digital camera all the way to hard copy proofing, I started using Adobe's DNG Profile Editor to create a .dcp profile from a Colorchecker I shot. Next, I used Rags Gardner ACR calibration scripts (see here: http://www.rags-int-inc.com/ ) to really fine tune ACR settings like contrast, hue, brightness etc, get delta E's down. These values, together with the raw profile, I then applied to another picture I shot under the same lighting conditions. I then converted the raw file to ProPhoto RGB, and then absolute colorimetric to the printer profile. The printer profile had also been tuned with an iterative process using EFI Colorproof XF.

I have enclosed a jpg version of some real objects next to their reproduced counterparts. I'm not saying that every colour is perfect (let's say less than 1 delta E 2000), but this was the closest I could get using dcp profiles.

Mind you, it's not only reproducing colors found in fine art that is challenging. Think of photographing samples of wood panel floor (parquet), carpets, bricks, all for the purpose of offset-printing a catalogue with colors that need to be as close as possible to the original. Many commercial studio photographers I have met are struggling with this kind of work, and sadly more often than not, it's trial and error.

Regards,
Yann
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bill t.
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« Reply #47 on: January 24, 2012, 01:22:29 PM »
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Thanks for sharing that exercise and for pointing out those scripts and techniques.

I'm amazed a web image can make it to my Firefox screen with that much accuracy.  For my particular evaluation regimen, if I slightly brighten the image in PS those charts are pretty much spot-on.  There's a little blue contamination in the grey background here and there, maybe form a window or nearby object.  But remarkable overall.
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Roscolo
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« Reply #48 on: January 26, 2012, 04:44:14 AM »
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Roscolo:

What lighting are you evaluating the print and the original art work with?

Sorry I have neglected this thread. I evaluate print and original art under daylight (as in actual daylight), daylight balanced fluorescent, and 3200K lamps. I lean towards the 3200K lamps because most of the artwork and prints will be displayed under tungsten lighting conditions.

Used to use daylight tubes exclusively, but had enough scenarios where I relied on that lighting to make prints, then delivered prints and client looked at the prints in their home or studio under tungsten lighting where they will display them and they didn't always look as good.
« Last Edit: January 26, 2012, 04:47:50 AM by Roscolo » Logged
Tim Lookingbill
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« Reply #49 on: January 27, 2012, 09:36:42 PM »
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Sorry I have neglected this thread. I evaluate print and original art under daylight (as in actual daylight), daylight balanced fluorescent, and 3200K lamps. I lean towards the 3200K lamps because most of the artwork and prints will be displayed under tungsten lighting conditions.

Used to use daylight tubes exclusively, but had enough scenarios where I relied on that lighting to make prints, then delivered prints and client looked at the prints in their home or studio under tungsten lighting where they will display them and they didn't always look as good.


If you're not editing your images so they appear pleasing under a particular light, then you're editing according to how the image looks on a neutral looking (6500K) calibrated display. You should never be editing your images for any particular light.

If prints match your calibrated display under one particular light (daylight fluorescent) and don't look correct under 2300K tungsten, something's wrong that can't be fixed by you, unless your client wants to not be so picky.

I've never had to edit my images for any particular light. My eyes quickly adapt to seeing the print under any given light except mercury vapor street lights which nothing looks good under.

The only color I can imagine not looking right under tungsten would have to be yellows, maybe purples, blues and cyans and where fresh, vibrant grass greens may look a bit cooked. But the warmth of the tungsten actually makes the print look better for these colors in my experience due to color constancy optical effects with WB color cast.

Below is an image I shot of a Skittles bag with my DSLR taken under all the lights I have and view my prints under. The Skittles bag was specifically chosen for its intense yellow to clearly show the spectral reflectance holes each artificial light brings out. As you can see the yellow looks a lot better under the GE Soft White tungsten (even better than actual daylight). It's a desirable color error. But this image is to really show how it's almost impossible to get a print to look the same under any given light unless you view them side by side under each light and that's not how we view prints.

The Smithsonian isn't concerned about these color errors viewing 100+ year old fine art painting under their MR16 tungstens, so why should your client?
« Last Edit: January 27, 2012, 09:41:32 PM by tlooknbill » Logged
Roscolo
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« Reply #50 on: January 28, 2012, 12:25:08 AM »
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As your illustration demonstrates, there is a huge difference between 6500K and 2800K household tungsten. We're talking blue vs. orange. Absolutely changes the appearance of artwork and prints and anything else that reflects light. Like I said, I try to look at prints vs. originals in both lighting conditions, but these days, for fine art repro, I tend to compare the prints I'm making against the originals under tungsten 3200K lighting as most of the work I am producing will be displayed in a gallery, museum or home environment under tungsten light. With fluorescents more common in homes now, that is changing for the home environment. My clients aren't picky so much as they want the print to match the artwork under the lighting in their environment. I do have many clients who want this level of accuracy, including a state museum. Hence my disappointment in the Colorchecker. I've always used just my own eyes, and my eyes are better than the Colorchecker. My expectations for the Colorchecker were perhaps a bit high. I have ordered the QP Card, though, thanks to the recommendation on this thread, and I'll report back how it does vs. the Colorchecker.

I'm an architectural photographer by trade. And I've operated a gallery for the last 20 years. I didn't really set out to be a fine art giclee' printer, but somehow the other two trades have somehow combined that I have gotten exponentially more and more clients for fine art repro, and those clients seem to have a higher and higher demand for accuracy. I stand corrected. You're right. They're damn picky! Smiley
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Tim Lookingbill
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« Reply #51 on: January 28, 2012, 11:52:20 AM »
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Quote
I've always used just my own eyes, and my eyes are better than the Colorchecker.

Quote
I try to look at prints vs. originals in both lighting conditions, but these days, for fine art repro, I tend to compare the prints I'm making against the originals under tungsten 3200K lighting

Inkjet ink on paper and paint or any other media in a fine art piece can have completely different spectral reflectance characteristics especially under 3200K tungsten lighting that make it impossible for a color target to fix all possible color perception errors. Note I said perception which isn't how the color on those targets are measured. The eyes are very forgiving when it comes to looking at the overall appearance of any object or scene lit by any particular light.

Also to consider is how would one know if it's the light, the paint/ink or our eyes causing the errors? And what's considered an error if the entire piece looks pleasing but a spectrophotometer indicates huge Delta E number discrepancies. Do we go with what's pleasing? or accurate according to the numbers?

Note the lemon yellow turning cadmium yellow under the tungsten lights of the Skittles shots. Which yellow is the correct one? Who defines it? Our eyes? or some spectrophotometer? What if we don't like what the spectrophotometer says it should look like according to the numbers? The X-rite Color Checker patch pigments are manufactured to exhibit stable, spectrally flat colors under a D50 light source as measured by a spectrophotometer. Fine art paint isn't.

You'ld have to create color target that exhibits every possible spectral reflectance induced color error compounded by both tungsten light and any odd spectral properties inherent in the pigments, suspension medium and substrate of any given fine art piece.

IMO I think you're better off fixing each color error by eye as you encounter with each fine art piece viewed under tungsten because I doubt you're going to have trouble with all the colors in all the pieces. But if this QP card gets you closer, then it may be worth the effort.

Look forward to seeing what you find.
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Tim Lookingbill
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« Reply #52 on: January 28, 2012, 12:18:55 PM »
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There's something else that came to mind that wasn't touched upon and that's the gamut of the inkjet ink compared to the fine art paint when viewed under tungsten.

The Skittles demo points to this issue even viewing on an sRGB display compared to a wide gamut display. I can tell you the way the Skittles yellow appears under the GE Soft Whites is a lot more intense than what I'm seeing viewing the image inline on my sRGB display in this thread. Because my eyes adapted to trying to match this intensity I thought I got pretty close, but after coming back, it isn't as intense as I'ld thought. I actually maxed out the yellow saturation in ACR on the Raw image. A dual illuminant camera profile didn't help either.

If you have paints in any of the fine art pieces that gain in similar intensity under tungsten, you may find your printer inks may be the limiting factor in which you'll have to know when to rule that out so you don't spin your wheels.
« Last Edit: January 28, 2012, 12:20:37 PM by tlooknbill » Logged
bill t.
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« Reply #53 on: January 28, 2012, 12:35:04 PM »
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Thanks for that excellent demonstration photo.  You should make a poster, would sell in droves to giclee makers.

Yes the spectral reflectance thing is one of the big bugaboos, not to mention the tendency towards metamerism which that and other effects bring to inkjet prints.  And there's this newly recognized kid on the block called "subsurface scattering" which is a close cousin to spectral reflectance.

Hey Roscolo, I'm feeling kinda poorly about having pitched that Colorchecker to you.  It works for my wife's very punchy pastel work (yes it's possible!) but have never tried it with subtle colors, or in situations where it's necessary to reproduce the subtle surface qualities and shading of the original media on the giclee media.

I just tried out the Datacolor "SpyderCHECKR" which is a sort of giant sized Passport.  It's got the exact same patches in a different arrangement, plus an additional 24 patches in much more subtle shades.  And yes, those deep-blue and crimson-red patches that the Devil put there are still present.

It's more trouble to use.  You have crop it tightly in Lightroom, then send that image to the Datacolor software.  But what it does is not create a DNG, but rather a lightroom preset with the controls in the HSL panel and elsewhere all tweaked around.  You need to have the same Lightroom profile applied as when you made the preset.  I have to say the match looked not too good last night under tungsten only, but this morning with sunlight coming through the windows it looks pretty decent, relevant to the tlooknbill was saying.  Would NOT want to say this is "the solution" but it's an interesting approach.  It also gives you a choice between what it calls "Saturation" and "Colorimetric" intents, Colorimetric seems to be more subtle.

I have also found that with the X-rite Passport, I can considerably get away from the slight oversaturation by playing with just the Hue and Luminance controls on just the red channel and magenta channels.  I think the X-rite Passport might be giving us a Saturation intent, rather than a colorimetric one, but I see no way to specify anything like that in the software.  

Also, I bought one of the QPCard201's from BH Photo and the darned thing only works through .jpg's!  Good grief, what's that about!  You apparently need the 203 model (or something) to work at the RAW, and nobody in the US seems to carry it.  Sigh.


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Roscolo
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« Reply #54 on: January 28, 2012, 03:02:24 PM »
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Also, I bought one of the QPCard201's from BH Photo and the darned thing only works through .jpg's!  Good grief, what's that about!  You apparently need the 203 model (or something) to work at the RAW, and nobody in the US seems to carry it.  Sigh.


You can order it straight from their website and it's less expensive that way also. The 201 is JPEG only. I ordered the 202 card and one of their neutral gray targets, QP 101. The QP 202 is larger and supposedly a little more sensitive than the smaller cards. The QP 202 is Only $45. Much more reasonable than the $90 - $100 passport Colorchecker. Check out their plug-ins for editing camera profiles. Some of the links don't work unless you create an account, but creating an account just entails putting in your name, address and an email address. There is a menu on the right for changing the prices from Euros to Dollars. And if you do an order, the tax is removed at the last step of the ordering process.

I'll follow up here when I get the thing as I'm going to try it on some of the same paintings I used the Colorchecker on. Once you know the Colorchecker's default is grossly oversaturated and know to correct for it, the Colorchecker is a little more useful. The level of accuracy I'm having to produce, no matter what I use, I will usually be having to go in and adjust individual areas of paintings. And that's not really such a big deal. Again, I didn't really ask for all this business in this area, but I usually go in the direction the customers and the $$$ guide me to.

Most of these customers have had prints made at online giclee' printers and other places, and these artists aren't getting the level of accuracy they need. So I've gotten tremendous word-of-mouth business in this area. I'm always able to get pretty spot-on accuracy, but with all the extra business, I just need to speed up the time / labor it takes to go from first proof to perfection.
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bill t.
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« Reply #55 on: January 29, 2012, 02:18:43 PM »
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Here's a smartphone pano of a gallery space.  6300K on the right, 2600K to the left, all on the same wall.  It's every giclee maker's worst nightmare and the bane of every artist and the norm for most galleries with a window at one end.

In taking pictures of installations in my customers' homes I often see interior walls in the 2600K to 2800K range.  That's the same color temp as sodium lighting, but of course with a more complete but still highly biased spectrum.  What can we do about these situations?  The answer...get used to them.

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digitaldog
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« Reply #56 on: January 29, 2012, 02:26:50 PM »
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One of my worst nightmares is hearing the ‘term’ giclee. ;-)

Our eyes and visual system would treat the scene you illustrate quite differently than the smartphone (or any camera system).
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Andrew Rodney
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Nigel Johnson
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« Reply #57 on: January 29, 2012, 02:39:30 PM »
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Here's a smartphone pano of a gallery space.  6300K on the right, 2600K to the left, all on the same wall.

OFF TOPIC

Bill,

If only the photo was a raw file, it looks like a perfect image to try out the localised colour temperature adjustment in LR4 Beta! I wonder how well it would work on the JPEG - when I have installed the beta (currently doing backups before a necessary OS upgrade) I may give it a try.

Regards
Nigel
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bill t.
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« Reply #58 on: January 29, 2012, 03:34:46 PM »
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One of my worst nightmares is hearing the ‘term’ giclee. ;-)

Our eyes and visual system would treat the scene you illustrate quite differently than the smartphone (or any camera system).

And that is generally the case at the gallery, the eye does not register either blue or yellow walls even when it can see both areas at the same time.

HOWEVER, I have to insist that the overall psyhological effect of say an image with either a markedly cool or warm ambiance is different over in the cool window light to the right, versus in the warm light to the left.  It's pretty dramatic in some cases.  And of course most of the print colors look different in the two extremes, although very few viewers pick that up directly.
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Tim Lookingbill
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« Reply #59 on: January 29, 2012, 06:37:52 PM »
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It looks as if LED's are improving enough to please museum curators as shown here...

http://www.hogarthlighting.co.uk/acatalog/ironmongershall.html

I'm a bit skeptical LEDs could make paintings look that good since they have far worse spectral reflectance qualities than some daylight balanced fluorescents. Right now they're just too expensive for me to try them out.
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