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Author Topic: ACR workflow for photography of paintings  (Read 151309 times)

George Middleton

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ACR workflow for photography of paintings
« on: June 10, 2015, 12:26:13 pm »

Dear Luminous Landscape experts,

I’m hoping you may be able to suggest improvements to or advice and feedback about my ACR workflow so that I might capture and process colors more accurately. I’m a painter and photograph my own work, from which I prepare jpegs to post on my website. The work is for sale so an accurate representation of colors is important.

My current capture workflow:

I shoot outdoors on overcast days against a wall with white background paper using a Canon 550D and a Canon EF-S 60mm f/2.8 Macro USM lens with a tripod and remote shutter.

I set up the shot and then shoot a custom white balance reference through a white balance lens cap, which I then set the camera to use. I then shoot a number of exposures of the painting, aiming for ISO 100 and 1/125 shutter speed and f5.6. If the lighting changes noticably during the shoot, I’ll redo the custom white balance.

My processing workflow:

I bring the RAW images into ACR viewing them on a warmed-up NEC PA301W wide gamut monitor calibrated every two weeks with the NEC MDSV puck. I use the NEC Spectraview II software set on “Photo Editing” with a D65 white point Gamma 2.20 and the “native” gamut. I have the advantage of comparing my RAW captures with the actual painting.

I have ACR set as follows: Camera Profile: Adobe Standard, Lens correction enabled for the Canon 60mm lens.

My results prior to any white point or color adjustments in ACR:

Paintings with muted colors seem pretty accurate, requiring very little correction. Paintings with strongly saturated hues- particularly blues but also reds, yellows, and greens exhibit noticable hue and saturation shifts definitely requiring correction. Some shots seem to require none or very little white balance adjustment, while others require a large WB adjustment. Any large WB adjustment tends to improve the colors to a good “starting” place.

If I apply any of the in-camera settings to the image in ACR- such as “Camera Neutral”, “Camera Standard” etc, they usually seem pretty de-saturated compared to Adobe Standard, so I leave it set to Adobe Standard as the starting point.

My post-processing workflow:

After doing any WB adjustment, I try to do most of the color correction in ACR. A file is then output to PS at the (default) size in ProPhotoRGB 16bit and a “master” image is saved. (In addition to jpegs for the internet, I’ll eventually make another targeted file for an archival quality inkjet print.) Spot removal, cropping etc are then done to the image. I’m still experimenting whether it’s best to do my capture sharpening in ACR or PK Sharpener. If other color corrections are still needed, I’ll do these with adjustment layers and masks. I’m still learning the various basic techniques in PS for targeted color corrections.

From the corrected master image, I duplicate the file, prepping it for output as a jpeg. Viewing the image as sRGB with the soft-proofing function, I notice that images of paintings with muted colors shift very little; those with strongly saturated colors exhibit noticable shifts regardless of ReCol or Perceptual rendering intents. I then try to bring those shifted colors into line using adjustment layers. After a PK Sharpener output sharpening, a jpeg of the appropriate size is then made with sRGB embedded.

My questions:

1. Will I benefit by using the X-rite ColorChecker Passport- shooting a reference color card before and after each photo shoot, and creating a twin-illuminant custom camera profile for use in ACR with the images from that particular photo shoot?

2. Am I overlooking anything obvious that could give me more accurate captures to begin with, or in any other part of my workflow?

3. If I am doing everything possible for color accuracy up front, should I adjust my attitude and expectations to accept the results as viewed in ACR as always a starting point, and that color adjustments big or small to the RAW capture are inevitable and normal?

4. If I am doing everything possible for color accuracy in adjustments to the RAW capture and the master image, should I adjust my attitude and expectations to accept the conversion to an sRGB jpeg- with it’s resulting small or large color shifts- as a starting point, and that color adjustments big or small to the jpeg-targeted file are inevitable and normal?

Thank you very much for reading this, and for your advice and suggestions!
-George
« Last Edit: June 10, 2015, 12:42:56 pm by George Middleton »
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AlterEgo

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Re: ACR workflow for photography of paintings
« Reply #1 on: June 10, 2015, 12:54:20 pm »

read this topic = http://forum.luminous-landscape.com/index.php?topic=100015.0

you will discover (if you survive the reading) a lot of good things, including that reproduction of paintings includes making targets with the same paints ...  and that your paintings (and targets) you need to photograph under the same controlled light ... and you do not want to use white background.
« Last Edit: June 10, 2015, 12:58:27 pm by AlterEgo »
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mouse

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Re: ACR workflow for photography of paintings
« Reply #2 on: June 10, 2015, 04:06:32 pm »

Dear Luminous Landscape experts,

I’m hoping you may be able to suggest improvements to or advice and feedback about my ACR workflow so that I might capture and process colors more accurately. I’m a painter and photograph my own work, from which I prepare jpegs to post on my website. The work is for sale so an accurate representation of colors is important.

I hate to be the bearer of bad news, but..  If your principal concern is accurate representation of colors in the images, as viewed on your website, by prospective customers on their monitors, using their browsers, you are fighting a loosing battle.

Consider that, if you are experiencing problems with color accuracy on your own monitor, after all your efforts at calibration and correction, just imagine what happens to the image after uploading to the web site and then downloading via an unspecified (and quite possibly non-colormanaged) browser to a monitor whose quality and calibration are well beyond your control.

The good news is that, I would imagine any reasonably sophisticated prospective purchaser of art work would not rely very heavily on the subtle differences in saturation and hues as seen on a web image.
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digitaldog

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Re: ACR workflow for photography of paintings
« Reply #3 on: June 10, 2015, 04:17:27 pm »

I hate to be the bearer of bad news, but..  If your principal concern is accurate representation of colors in the images, as viewed on your website, by prospective customers on their monitors, using their browsers, you are fighting a loosing battle.
Absolutely. We don't know what kind of display calibration if any they have, what browser, whether it's color managed. You're going to be reducing everything to SatanicRGB (sRGB). It will not hurt at all to build a custom DNG camera profile for your sensor. But you can throw 'accurate' and 'color' out the window. Make them look as good as you can on your calibrated and profiled display while soft proofing to sRGB then hope for the best with respect to what anyone else will see from those numbers.
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Andrew Rodney
Author “Color Management for Photographers"

George Middleton

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Re: ACR workflow for photography of paintings
« Reply #4 on: June 10, 2015, 04:55:23 pm »

I hate to be the bearer of bad news, but..  If your principal concern is accurate representation of colors in the images, as viewed on your website, by prospective customers on their monitors, using their browsers, you are fighting a loosing battle.

Absolutely. We don't know what kind of display calibration if any they have, what browser, whether it's color managed. You're going to be reducing everything to SatanicRGB (sRGB). It will not hurt at all to build a custom DNG camera profile for your sensor. But you can throw 'accurate' and 'color' out the window. Make them look as good as you can on your calibrated and profiled display while soft proofing to sRGB then hope for the best with respect to what anyone else will see from those numbers.

read this topic = http://forum.luminous-landscape.com/index.php?topic=100015.0

Thank you all very much for the replies. I will read the article, and yes- I understand I am dealing with a situation where the best I can hope for is an end result that is reasonably accurate to my eyes on my monitor.
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mouse

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Re: ACR workflow for photography of paintings
« Reply #5 on: June 10, 2015, 05:14:55 pm »

Thank you all very much for the replies. I will read the article, and yes- I understand I am dealing with a situation where the best I can hope for is an end result that is reasonably accurate to my eyes on my monitor.

That's fine as long as you recognize that the reasonably accurate result viewed on your monitor may bear little resemblance to what the prospective customer sees on their monitor. :)
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kirkt

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Re: ACR workflow for photography of paintings
« Reply #6 on: June 11, 2015, 03:44:25 pm »

Take a look at this write-up about exactly what you are trying to understand:

http://trumpetpower.com/photos/Exposure

kirk
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rubencarmona

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Re: ACR workflow for photography of paintings
« Reply #7 on: June 12, 2015, 10:12:45 am »

I'm an artist myself and to reproduce my paintings I use a SpyderCheckr and feel quite good as I processed my images (on a calibrated monitor) and printed them at a print store. The colors came surprisingly near to the originals. So +1 for the color reference card.
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Ann JS

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Re: ACR workflow for photography of paintings
« Reply #8 on: June 12, 2015, 03:42:28 pm »

Just one thought: do you paint with acrylics?

I have come across a number of pigments which must be emitting in the UV or IR ends of the spectrum because they record on both film and sensors very differently from the way that the human eye perceives them.

You may have to isolate these colours onto separate masked layers in Ps and adjust each one manually.
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George Middleton

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Re: ACR workflow for photography of paintings
« Reply #9 on: June 17, 2015, 11:54:26 am »

Just one thought: do you paint with acrylics?

Thanks for the tip Ann. Yes I do paint with acrylics.
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George Middleton

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Re: ACR workflow for photography of paintings
« Reply #10 on: June 17, 2015, 12:13:28 pm »

Take a look at this write-up about exactly what you are trying to understand:

http://trumpetpower.com/photos/Exposure

kirk

Thanks Kirk, looks like  a great all-in-one reference.

read this topic = http://forum.luminous-landscape.com/index.php?topic=100015.0

you will discover (if you survive the reading) a lot of good things, ..

I read the entire thread. Amazing bunch of scientists and engineers to say the least..
I now have a better understanding of the issues involved in characterizing a sensor.

I started using the ColorChecker, and I see a definite improvement right off the bat in ACR using the custom camera profile. It was interesting that when I attempted to make a dual-illuminant profile with ColorChecker captures from the beginning and end of the shoot- the software said no go- illuminants are the same, tho I thought the outdoor lighting had fluctuated a bit..

I'm an artist myself and to reproduce my paintings I use a SpyderCheckr and feel quite good as I processed my images (on a calibrated monitor) and printed them at a print store. The colors came surprisingly near to the originals. So +1 for the color reference card.

Thanks Ruben, that's very encouraging.

.. including that reproduction of paintings includes making targets with the same paints ...  and that your paintings (and targets) you need to photograph under the same controlled light ... and you do not want to use white background.

AE, I don't understand yet why I would not want to use a white background.. (I'm such a beginner :))

As for creating a custom color card with my artist's pigments- is there a recommended software to 'read' the card, or can I fool ColorChecker into doing that? What would be the important parameters to follow in making such a card?

One of the main things I've learned during my latest ACR-centric workflow compared with my earlier work- I've realized I was over-sharpening way too early..
« Last Edit: June 17, 2015, 12:16:10 pm by George Middleton »
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AlterEgo

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Re: ACR workflow for photography of paintings
« Reply #11 on: June 17, 2015, 12:21:06 pm »

AE, I don't understand yet why I would not want to use a white background
idea was that anything that will alter (reduce) the contrast through unwanted reflections back to your lens is bad...
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AlterEgo

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Re: ACR workflow for photography of paintings
« Reply #12 on: June 17, 2015, 12:28:06 pm »

As for creating a custom color card with my artist's pigments- is there a recommended software to 'read' the card, or can I fool ColorChecker into doing that? What would be the important parameters to follow in making such a card?

again that is what people who do serious reproduction work are apparently doing - they create a chart using the pigments matching the painting (which is certainly not an easy process), measure those patches with spectrophotometer and then the program like the one Torger created can use the data for profile building... but then anybody will be wise to start with basics - that is with a off the shelf target with all the fine strings shown in that topic about glossy/semi-glossy targets vs matte targets, avoiding drop in contrast and any unwanted reflections, etc, etc... even the simplest thing like take a shot of colorchecker passport ends up as a serious excercise once you start paying attention to all those nuances... like one joke (with a good portion of truth in it) from one other forum - do not wear blue jeans while standing close to the target when you are shooting it.
« Last Edit: June 17, 2015, 12:31:22 pm by AlterEgo »
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Lundberg02

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Re: ACR workflow for photography of paintings
« Reply #13 on: June 18, 2015, 02:31:42 am »

From my feeble attempts to photograph some of my collection, I can certainly say that avoiding any reflections is critical, especially with oils and acrylics.  Another thing, I believe you are saying that you convert from Pro Photo to sRGB in Photoshop with Perceptual rendering intent? No you aren't. Photoshop does not do anything but Relative when converting an image from Pro Photo to aRGB or sRGB. You can install an icc profile for sRGB that will allow perceptual, but you have to go find it wit a bit of googling. You can SEE perceptual by soft proofing, but you can only GET it by printing and using the printer mfg's perceptual rendering intent. I know of no icc profile with aRGB perceptual that can be installed, but every decent printer has it. You might want to make sure your calibration profile is actually perceptual as well ( the subject of a recent thread in Color Management).
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George Middleton

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Re: ACR workflow for photography of paintings
« Reply #14 on: June 21, 2015, 07:49:04 am »

idea was that anything that will alter (reduce) the contrast through unwanted reflections back to your lens is bad...

Ok, thanks AE. I've got gray and black background paper now- I'll be trying those on the next round of captures.. and also reducing as much as possible the background area around the painting.
« Last Edit: June 21, 2015, 08:03:15 am by George Middleton »
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George Middleton

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Re: ACR workflow for photography of paintings
« Reply #15 on: June 21, 2015, 08:11:06 am »

again that is what people who do serious reproduction work are apparently doing - they create a chart using the pigments matching the painting (which is certainly not an easy process), measure those patches with spectrophotometer and then the program like the one Torger created can use the data for profile building... but then anybody will be wise to start with basics - that is with a off the shelf target with all the fine strings shown in that topic about glossy/semi-glossy targets vs matte targets, avoiding drop in contrast and any unwanted reflections, etc, etc... even the simplest thing like take a shot of colorchecker passport ends up as a serious excercise once you start paying attention to all those nuances... like one joke (with a good portion of truth in it) from one other forum - do not wear blue jeans while standing close to the target when you are shooting it.

Thank you, I had really no appreciation for this at all before, other than say an obvious reflection from a glossy painting.

I'm beginning to literally see the more subtle effect of reflections from other sources- not so much when I do the captures- my setup seems to be fairly 'clean' that way- but when I compare the captures with the paintings indoors, I've realized I cannot do that properly indoors- too many colors bouncing from other sources and lighting that is substantially different from the capture lighting...

To get a better comparison I run outside, look at the painting still on the wall, then run inside and compare... I suppose it's time for a tethered setup!
 
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George Middleton

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Re: ACR workflow for photography of paintings
« Reply #16 on: June 21, 2015, 08:20:07 am »

From my feeble attempts to photograph some of my collection, I can certainly say that avoiding any reflections is critical, especially with oils and acrylics.  Another thing, I believe you are saying that you convert from Pro Photo to sRGB in Photoshop with Perceptual rendering intent? No you aren't. Photoshop does not do anything but Relative when converting an image from Pro Photo to aRGB or sRGB. You can install an icc profile for sRGB that will allow perceptual, but you have to go find it wit a bit of googling. You can SEE perceptual by soft proofing, but you can only GET it by printing and using the printer mfg's perceptual rendering intent. I know of no icc profile with aRGB perceptual that can be installed, but every decent printer has it. You might want to make sure your calibration profile is actually perceptual as well ( the subject of a recent thread in Color Management).

Ok, I didn't realize that. On my system, in "convert to profile", it allows a preview in either RC or Perc with a ProPhoto image.. Whether that's actually happening under the hood I don't know.
But from my research, most are recommending RC anyway. All my recent captures I'm doing RC on the conversion to sRGB- I see no or barely any difference anyway when I try them both.

The only time I see a real difference between RC and Perc is when I soft-proof the ProPhoto image with different printer/paper profiles.
« Last Edit: June 21, 2015, 08:22:11 am by George Middleton »
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George Middleton

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Re: ACR workflow for photography of paintings
« Reply #17 on: June 21, 2015, 09:23:37 am »

I'm an artist myself and to reproduce my paintings I use a SpyderCheckr and feel quite good as I processed my images (on a calibrated monitor) and printed them at a print store. The colors came surprisingly near to the originals. So +1 for the color reference card.

Yes, thank goodness. I've noticed the same in my recent work. If the exposure and white balance are right, the colors just seem to fall in line with very little correction needed. Before, I used the ColorChecker, there were colors I thought maybe the 550 couldn't capture but now that doesn't seem to be the case.

However, while most of my work converts to sRGB with little or no obvious change, in some images, there are definitely a range of saturated blues, magentas, aquas that basically get depressingly compressed and desaturated- really altering the look of the painting. I don't yet know how to compensate for those- or if it's even possible. I've been trying various types of adjustment layers on a copy of the ProPhoto image while soft-proofing in sRGB, but no joy so far..

Truly Satanic RGB as Andrew says!
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Lundberg02

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Re: ACR workflow for photography of paintings
« Reply #18 on: June 26, 2015, 12:02:42 am »

As usual, googling produces TMI without directly answering my question, but I get the impression that the gamut of acrylics is smaller than sRGB. CMYK might be a different story. I could not find an article or image that showed the gamut of acrylic art paint or oil paint either, superimposed on CIE. These gamuts have to be smaller than Adobe RGB monitor color, because they aren't emissive.
So I don't think you need to worry about rendering much. If you had ColorThink you could make scatter diagram of the actual loci and probably see that any given painting has a very restricted space.
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George Middleton

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Re: ACR workflow for photography of paintings
« Reply #19 on: June 26, 2015, 08:51:14 pm »

As usual, googling produces TMI without directly answering my question, but I get the impression that the gamut of acrylics is smaller than sRGB. CMYK might be a different story. I could not find an article or image that showed the gamut of acrylic art paint or oil paint either, superimposed on CIE. These gamuts have to be smaller than Adobe RGB monitor color, because they aren't emissive.
So I don't think you need to worry about rendering much. If you had ColorThink you could make scatter diagram of the actual loci and probably see that any given painting has a very restricted space.

Thanks Lundberg.
I don't know- it does seems like the sensor is capturing all the colors and the wide gamut monitor is displaying them...

But with certain vivid blues, turquoises, and yellow greens in certain paintings and in their corresponding ProPhoto files- upon conversion to sRGB, those particular colors are squashed pretty good is the problem.. not a pretty translation and RI doesn't make a difference. The colors look accurate to me on screen in the ProPhoto file comparing with the ptg.

The paintings without those particular saturated colors translate nicely with very little shift if any.

But maybe I’m not taking the pics right, still learning picture-taking 101.

One thing I just discovered-
The paintings with substantial varnish, all their captures seemed soft, not sharp to me. At first, I thought it was my focusing, or autofocus wasn’t finding focus well.. Switched to all manual focusing with the magnified option and same results..

Then I captured a painting <without> varnish and it was tack sharp- wow, now I see what they been sayin’ bout that Canon 60mm lense. At least I think this is the case; we’ll see on the next round..
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