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: Tue, 04 Jun 2013 00:24:06 +0100
And with Nikon D90 get dE2000=1.67 with flash units without Pirex on a
ColorChecker. Where is your goal?. And your images from X-ray or UV, where
do you evaluate and compare?, isn't a display?. And when you go to any kind
of meeting or to publish your analysis and conclusions, don't you print on
paper?.
2013/6/3 José Ángel Bueno García <email@hidden>
> 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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