Re: Colorimetric Accuracy in the Field
Re: Colorimetric Accuracy in the Field
- Subject: Re: Colorimetric Accuracy in the Field
- From: José Ángel Bueno García <email@hidden>
- Date: Mon, 03 Jun 2013 23:57:39 +0100
I'm photographer. I do not art. Go out with your Sinar and your SG
ColorChecker.
2013/6/3 Stanley Smith <email@hidden>
>
> Those of us in the museum world are very concerned with colormetric
> accuracy, and go to great lengths to achieve this-- even to the point of
> developing multi-spectral capture methods (I worked recently with Roy
> Berns and Sinar AG to develop a six-channel system that achieves
> accuracy on a SG ColorChecker of less that 1 CIEDE2000). Our need for
> this has little to do with how the image ends up looking on what ever
> display or paper-- it is mostly useful in scientific painting
> conservation analysis. I honestly cannot think of another situation
> where this level of accuracy is useful or practical. It's like walking
> towards a wall in intervals covering half the distance each time. Will
> you ever get to the wall? No, but you'll be close enough.
> Photographers don't care-- they goose the colors later anyway to express
> their interpretation of a scene-- this is not new-- Ansel burned and
> dodged fiercely. Leave the science to the scientists. Go out and make
> art.
>
>
>
>
>
> Stanley Smith
> Head of Collection Information and Access
> J. Paul Getty Museum
> 1200 Getty Center Drive, Suite 1000
> Los Angeles, CA 90049-1687
> (310) 440-7286
>
>
>
> >>> On 6/3/2013 at 02:49 PM, in message
> <email@hidden>, Jeffrey Stevensen
> <email@hidden> wrote:
>
>
> 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."
>
> >
> >> 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
> >
> > 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?
> >>
>
> 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
> >
>
> 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.
> >
> > 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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