Colorimetric Accuracy in the Field
Colorimetric Accuracy in the Field
- Subject: Colorimetric Accuracy in the Field
- From: Jeffrey Stevensen <email@hidden>
- Date: Mon, 03 Jun 2013 17:49:00 -0400
I've been following this discussion and though it is geek-intriguing, in which I include myself. And I'm still catching up. But it seems completely irrelevant to being a working photographer in the field. Mr. Goren seems to be advocating, to use a reference to our earlier, photo-chemical past, "the perfect film developer."
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>> I'm sure I could have taken my i1 Pro into the field with me and gotten spot measurements of everything in sight I could lay my hands on
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> Indeed, that's hard and a lot of work. But short of that, what proof do we have? Isn't the goal of colorimetry an non ambiguous set of color measurements that don't rely on a personal interpretation of what we see as color?
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I've got to side with Mr. Rodney throughout. He asks for the definition of "colorimetric accuracy" and in reply gets assurances based on memory. If I stand on a beach at magic hour in golden light, is the goal a capture of the subject in a perfect colorimetric rendering of that moment's unique and beautiful light, which is what I take to be the end result of some in the "pro-colorimetric" side of this debate? Certainly not a capture of the subject that ignores the momentary unique lighting and says, this is what it would have looked like under some sort of "standard" light; there would be no point to doing that except for some scientific goal with clearly stated conditions of measurement accuracy and toolset accuracy.
I think I'm interested in reproducing my perception of what I see, which is the object or scene in that unique lighting, and hopefully a little extra personal poetry of imagination. Anything requiring "matching" must state all the objectively-measured conditions and definitions of what is a match. That masterful matching print of the painting or museum piece will definitely include the specification for the conditions of viewing, including lighting levels, lighting color temperature, evenness, etc. to stay within the accepted deviation constituting a "match." There is no such thing as the original and copy matching to some fine, objective numeric standard across all mediums and viewing conditions. And even if it did, Mr. Goren states
>>> Colorimetry is "the science and technology used to quantify and describe physically the human color perception
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Ah! We are back to human perception, "perceptual rendering"! Anybody on this list care to step up and claim to have perfect human "standard observer" vision?
> in contrast, my workflow with Raw Photo Processor amounts to shooting a target, feeding that target to a Perl script that spits out white balance and exposure numbers, doing a copy / paste of those (three) numbers back into Raw Photo Processor, and applying those settings to the shot of the artwork. That's the sum grand total of my color-correcting workflow; everything else is either sharpening or lens geometry and peripheral illumination correction or panorama-type stitching or cleaning up smudges on the original or the like.
So rendering the scene from raw as described, personal expression is thus confined to… composition only? Choice of subject? Angle of view? Perspective and lens choice? Just going to a momentary 2D rendering? How is this "accurate" to a changing, moving, scene-scanning, 4D space-time personal experience through one unique set of eyeballs?
> I output from RPP to a BetaRGB TIFF, do whatever needs to be done in Photoshop without any color transformations, and then feed the BetaRGB TIFF to Argyll for a gamut-mapped perceptual rendition to the printer profile, and print the result.
We all want and usually get pretty close to making the print look awfully "accurate" in an ICC-manged workflow with a variety of tools, but this comes after rendering the raw file to where we like it, so no argument there.
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> I daresay getting comparable quality out of Adobe's rendering engine, if even possible, would require many, many hours of very intensive and skilled post-processing.
To be science, one must specify all the conditions under which the experiment is conducted, the single variable to be tested and how the final result is then measured. Mr. Rodney is right that that has not been provided, nor is what artists do, nor even generally what clients hire photographers to do.
My sincere appreciation to all parties for a fascinating diversion, but now to make some money...
Jeff Stevensen Photography
82 Gilman Street
Portland, ME 04102
207-773-5175
207-807-6961 cell
http://www.jstevensen.com
blog http://photosightlines.com
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