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Author Topic: DCF Full Spectrum plug-in  (Read 66614 times)
nemophoto
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« Reply #40 on: April 24, 2006, 11:01:57 AM »
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Frankly, all this is "much ado about nothing". Either use the pluggin. . . or not. It does work. I shoot fashion where color is always a problem with garments. Most files are handed to clients in AdobeRGB (their request). In my view, I've done my job when I can get the garments as close as possible. It's the pre-press house that needs to do final color matching.

Andrew's example of how he matched the purple-ish Laker's jersey has a flaw. Sure, he matched the purple, but the gold was still off and greenish on my monitor (yes, calibrated).

The point is, you can chose to buy the plugin or not. I've bought lots of pluggins and actions over the years that have proved either ineffective or a waste of money. Case in point: Andrew's own PixelGenius enterprise produces PhotoKit Sharpener. I bought it. Used it some and decided I prefer using Nik Sharpener 2.0. It's not that PK Sharpener is no good, only my preference.

It's sad to see people be so bombastic in their approval or disapproval of products. There are lots out there that ARE total garbage. In this case, we're talking subtleties, not a "blow you away" pluggin. To me, a lot of this smacks of a "turf war" and who's the expert or not.
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digitaldog
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« Reply #41 on: April 24, 2006, 11:12:28 AM »
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Andrew's example of how he matched the purple-ish Laker's jersey has a flaw. Sure, he matched the purple, but the gold was still off and greenish on my monitor (yes, calibrated).
[a href=\"index.php?act=findpost&pid=63567\"][{POST_SNAPBACK}][/a]

Looks just fine to me (yup, calibrated display). Are the two sets of RGB numbers identical? Probably not. But that's a moot point. I could easily have messed with the yellows too. The color appearance after my edit doesn't seem to be an issue.

What IS an issue is the BS factor of the site selling this product. I think we've all been pretty clear that a plug-in that provides  a "make blues pretty" button is fine as long as you tell folks that's what it does. But to put up a bunch of bogus technical nonsense about how cameras can't "see" blue or suggesting you photography your display when viewing their site and examining the LCD on a PHD camera as evidence that there's some kind of color issue with digital cameras is insulting and well, plain BS.

No one is disputing the plug-in might have merit for some users who don't know Selective Color in Photoshop from the crop tool. If it fixes your blues and you find the $50 a worthwhile investment, far from anyone to fault that. But lets cut the Krap and stop providing URLs that don't back up the fact that the premise provided on the web page about this product is Krap.
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Andrew Rodney
Author “Color Management for Photographers”
http://digitaldog.net/
PeterLange
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« Reply #42 on: April 24, 2006, 04:53:48 PM »
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“Existing, practical cameras and scanners have spectral responses that don't closely resemble either the cone fundamentals or transformations of the CIE color matching functions. Therefore, these cameras see some colors differently from the way that vision sees those colors.”


Nope; sorry I have to disagree.


Michael,

In the meantime state-of-the-art digital cameras were reported to have a metamerism index of above 90% or so (according to ISO 17321).  Since perfect color reproduction is scaled to a value of 100, any sensor that achieves a metamerism index above 90 should be capable of providing great color.

Actually the spectral response of Bayer R/G/B filters can come close enough to a linear combination of the CIE XYZ matching functions (depending on the camera of course). So that a simple 3 by 3 matrix can be used in software to recover the corresponding XYZ values, or for direct conversion to a common output space like sRGB, aRGB, pRGB ...  In other words, within a quite large 'triangular' matrix gamut digital cameras see nearly the same as the human obverver. Note, I don’t say perfectly.

Talking about: a preferred color reproduction, a pleasing rendition (output-referred), Color Appearance Models, etc. ... that’s a different story.

So where exactly lies the problem which your plug-in intends to cure?

Please be clear.

Peter

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allan67
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« Reply #43 on: April 24, 2006, 06:09:27 PM »
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I did a test today to see if there's really a problem with DSLR not seeing purple colours.
Used 30D to take a shot of my MTB club jersey - it has a very nice gradient from light blue through deeper blue to purple. Effectively, on the camera's LCD the colours really looked very much off - the purple became blue and blues were shifted to cyan. BUT, when the RAW file was opened in ACR 3.3 (calibrated for the shooting conditions using GMB chart as explained by Bruce and others) everything became very much normal - all hues snapped to their correct values and the screen to object match was nearly perfect (needed a bit of saturation increase to get exact match).
FWIW.
Allan
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Hermie
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« Reply #44 on: April 25, 2006, 05:27:39 AM »
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From the FAQ's on Munsell Color Science Laboratory:

Question:
"Digital image sensors (such as those used in digital cameras)use red, green, blue ink-based color filters to generate color. Do they therefore have a color gamut that limits the range of colors that they can detect? (255)"

Answer:
"Let's start with the short answer to your question; there is no such thing as a camera, or scanner, gamut. A gamut is defined as the range of colors that a given imaging device can display. To say that a camera had a gamut would be to imply that you could put a color in front of it that it could not possibly respond to. While it is certainly possible that two colors that are visually distinct might be mapped into the same color signals by a camera, that does not mean that the camera could not detect those colors. It just couldn't discriminate them. For example, a monochrome sensor will map all colors into a grayscale image and encode it as such. Certainly the encoding has a gamut (in this case a lightness range with no chroma information), but did the camera responded to all the colors put before it. It is the encoding that imposed the gamut. In the color world, encoding is based on some explicit or implied display. For example, sRGB is a description of a display and therefore defines a gamut (but only if the sRGB values are limited in range). If a camera encodes an image in sRGB, that doesn't mean that the range of colors the camera detected are only from within the sRGB display gamut, but it means the camera data have been transformed to best use that sRGB encoding. As long as a camera has three or more sensors that span the visual spectrum, then it will respond all the same stimuli as our visual system. Whether the camera can discriminate colors as well as the human visual system will depend on the encoding of the camera signals, quantitization, and the details of the camera responsivities. (To return to the black and white system, that camera encodes all the colors into a gray scale. They could then be displayed as any color within a given display, but many colors from the original scene would be mapped to the same values.)

Since there is no such thing as a gamut for an input device, then there is no way to compute it or calculate a figure of merit. Generally, the accuracy of color capture devices is assessed through the accuracy of the output values for known inputs in terms of color differences. Also, sensors are sometimes evaluate in terms of their ability to mimic human visual responses (and therefore be accurate) using quantities with names like colorimetric quality factor, that measure how close the camera responsivities are to linear transformations of the human color matching functions. Doing an internet search on "colorimetric quality factor" will lead you in the right direction."

Herman
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jani
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« Reply #45 on: April 25, 2006, 06:47:49 AM »
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Guys, the horse is nearly a wet puddle on the ground, it can't pull the plow anymore.
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Jan
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« Reply #46 on: April 25, 2006, 10:39:32 AM »
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Guys, the horse is nearly a wet puddle on the ground, it can't pull the plow anymore.
[a href=\"index.php?act=findpost&pid=63638\"][{POST_SNAPBACK}][/a]
No kidding, there's nothing left to beat.
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PeterLange
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« Reply #47 on: April 25, 2006, 01:46:11 PM »
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From the FAQ's on Munsell Color Science Laboratory: ...

Hermie,

Please let me briefly comment on this Munsell quote, because I still believe that the whole story is much simpler than it seems:

The naked RGB triplets as released from Bayer interpolation *can* be assigned to a quite large matrix space as the input profile. To my best knowledge, that’s the way Camera Raw works. And this approach will work so much the better, the closer the spectral response of Bayer R/G/B filters comes to a linear transform of the CIE XYZ matching functions.

BUT – unlike output devices which have a rigid output gamut – this input gamut more describes a sphere of accuracy. Within this sphere the camera 'sees' about the same as the human observer. But, even outside from this sphere, a camera will probably respond to 'everything’ like e.g. spectrally pure laser beams. Just, this doesn’t lead to accurate data.

So if the Munsell lab likes to capture laser beams, then they’re right. There’s probably no camera and input gamut (which would be suited for such purposes). However, from a practical perspective the input gamut of today’s cameras is large enough for almost everything coming in front of my lenses.
 
 
Anyway, I’d still love to hear what Micheal Bevans from tribecalabs has to offer regarding the science part of his product. A nice ab initio explanation would be fine…

 Peter

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P.S.: Did you notice my post on sensor design + reference literature before RG forums went down.
« Last Edit: April 25, 2006, 01:54:45 PM by PeterLange » Logged
Hermie
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« Reply #48 on: April 25, 2006, 02:35:26 PM »
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P.S.: Did you notice my post on sensor design + reference literature before RG forums went down.
[a href=\"index.php?act=findpost&pid=63665\"][{POST_SNAPBACK}][/a]

No I didn't. Do you have any links for me?

Herman
« Last Edit: April 25, 2006, 03:24:04 PM by Hermie » Logged
Nick Rains
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« Reply #49 on: April 25, 2006, 04:49:15 PM »
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Equine flagellation aside...

It's interesting to note that Jon Cone sells the plugin on his site. I would imagine Jon can be assumed to know a thing or two about digital imaging.

I have the DCF plugin - Mike was kind enough to send me a copy for review and we exchanged emails about its effects.

I am no colour guru but I know what looks 'good'. My point to Mike was that I thought DCF made normal images 'less good' by making the blue skies too mag. and the greens too yellow. Now it may be that this is more 'accurate', but I personally don't want 'accurate' I want 'good' - not the same thing at all.

Blue skies with too much mag. are buggers to offset print, they are better to be slightly too cyan. However, digital camera do have a tendancy to exaggerate greens and Mike refers to the fluoro green effect. I like the bright greens but it is more accurate to tone them down and make them more yellow. Hence the example posted above is possibly more 'accurate' in the greens, but to my eye, I prefer the brighter green.

I was tempted to get out the GM chart but I thought what's the point? DCF does nothing for my files that I cannot do in PS and, on default, I don't like the effect.

Like Nemo says: get the plugin, check it out, if you don't like it, move on.

One effect that has not been mentioned is the Fill Light slider, a bit like RSP. This works very well with no mystery, and if some beginner had problems with certain tonal adjustments in PS then the plugin is probably worth having for this feature alone.
« Last Edit: April 25, 2006, 04:56:42 PM by Nick Rains » Logged

Nick Rains
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digitaldog
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« Reply #50 on: April 25, 2006, 05:37:42 PM »
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It's interesting to note that Jon Cone sells the plugin on his site. I would imagine Jon can be assumed to know a thing or two about digital imaging.

He knows a thing or two about selling... Other than that, I wouldn't assume anything. Or maybe Jon can come on down and take over for Mike about what this product is supposed to do (I submit again it's a make pretty button and there's nothing wrong with that. Let's just cut the technical nonsense off Mike's and Jon's site; both are used to sell the product and the marketing hype is over the top).

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I am no colour guru but I know what looks 'good'. My point to Mike was that I thought DCF made normal images 'less good' by making the blue skies too mag. and the greens too yellow. Now it may be that this is more 'accurate', but I personally don't want 'accurate' I want 'good' - not the same thing at all.

Accurate is a buzz word that really yanks my chain. Accurate is by my definition colorimetrically correct (measured) color of the scene and by virtue the capture from a digital camera is scene referred. It will be accurate and quite ugly! Our jobs is to make output referred color which can't be accurate by my definition but can be pleasing or what YOU the image creator which to express of the image. Accurate color is often used to sell something. This was used early on in the color management days and maybe that's why the term upsets me because so few are willing to define it. It makes selling SOOOO much more difficult once really defined!

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I was tempted to get out the GM chart but I thought what's the point? DCF does nothing for my files that I cannot do in PS and, on default, I don't like the effect.

I think most of us are in agreement on that!
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Andrew Rodney
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paulbk
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« Reply #51 on: April 25, 2006, 07:21:57 PM »
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re: "... I don't like the effect."

I agree. I own DCF and think the hype and theory on tribecalabs' web site is, at best, misleading. If not 100% boloney. I thought Jon Cone was a color/print expert so it must be worth a try. Not necessarily so. DCF adds too much magenta to clear blue skies and green grass. See my examples page 2 of this thread, post #36.

Live and learn.

fyi.. Jon Cone's DCF page here
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paul b. kramarchyk
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« Reply #52 on: April 25, 2006, 09:19:57 PM »
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Accurate is a buzz word that really yanks my chain. Accurate is by my definition colorimetrically correct (measured) color of the scene and by virtue the capture from a digital camera is scene referred. It will be accurate and quite ugly! Our jobs is to make output referred color which can't be accurate by my definition but can be pleasing or what YOU the image creator which to express of the image. Accurate color is often used to sell something. This was used early on in the color management days and maybe that's why the term upsets me because so few are willing to define it. It makes selling SOOOO much more difficult once really defined!
I think most of us are in agreement on that!
[a href=\"index.php?act=findpost&pid=63677\"][{POST_SNAPBACK}][/a]

I am actually far more interested in the way one sees colour and interprets vision than I am in technical colour stuff - although they are obviously related. it's a fascinating subject since it includes technology, psychology and physiology plus a bit of philosophy!

I, too, find the whole 'accuracy' concept flawed for real world applications such as selling nice photographs to hang on the wall and simply please the eye.
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Nick Rains
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PeterLange
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« Reply #53 on: April 26, 2006, 12:31:27 AM »
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By means of Calibrating Camera Raw:

“You’ll just get more accurate hue and saturation relationships in your images”.

Cited from: http://www.creativepro.com/printerfriendly/story/21351.html
by Bruce Fraser


Peter

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Nick Rains
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« Reply #54 on: April 26, 2006, 01:21:49 AM »
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By means of Calibrating Camera Raw:

“You’ll just get more accurate hue and saturation relationships in your images”.

Cited from: http://www.creativepro.com/printerfriendly/story/21351.html
by Bruce Fraser
Peter

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[a href=\"index.php?act=findpost&pid=63699\"][{POST_SNAPBACK}][/a]

Sure, and your point is?

I have done the calibration as describe by Bruce and indeed find the results reasonably 'accurate' vis a vis the theoretical Lab values of the test chart. But the world is not a test chart and I find the results, applied to real world subjects, less than totally pleasing - subjectively of course.
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Nick Rains
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PeterLange
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« Reply #55 on: April 26, 2006, 12:16:58 PM »
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I, too, find the whole 'accuracy' concept flawed for real world applications such as selling nice photographs to hang on the wall and simply please the eye. [a href=\"index.php?act=findpost&pid=63690\"][{POST_SNAPBACK}][/a]
.....

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Sure, and your point is?

I have done the calibration as describe by Bruce and indeed find the results reasonably 'accurate' vis a vis the theoretical Lab values of the test chart. But the world is not a test chart and I find the results, applied to real world subjects, less than totally pleasing - subjectively of course. [a href=\"index.php?act=findpost&pid=63700\"][{POST_SNAPBACK}][/a]

My point is that there's no way to nice photographs without a system-immanent idea of color accuracy.  It’s hardwired deeply inside the input-pipeline starting with the sensor design.

Other people like Mr. Canon and Mr. ACR have already sorted this out for us behind the scenes (more or less). Even more, they already provide a first basic suggestion for a pleasing rendition on the top, output-referred, so that the user can focus on this last step to get everything ‘right’ within the limited dynamic range of the monitor and printer.

Calibration can definitively improve the communication between both gentleman mentioned above.  And yes, there are different concepts how this can be accomplished.

You may not believe in this line of thoughts, but on the other side if accurate color counts nothing, would you allow your children to paint new Bayer filters for your camera, or, let them randomize and tape down the Calibrate tab settings in ACR? I wouldn’t.

Sorry for leaving the original topic of thread.

Peter

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bruce fraser
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« Reply #56 on: April 26, 2006, 01:50:02 PM »
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"Accurate" is not necessarily the final goal, but it tends to make for a much better starting point than randomly inaccurate....
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digitaldog
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« Reply #57 on: April 26, 2006, 02:26:43 PM »
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In the case of the ACR calibration routine, you're taking output referred numbers in a defined color space and attempting to match those numbers to a target that would have those same values output preferred. So in this case, I think hitting those values (and I've never got dead nuts exact numbers but close), does assist in getting a good starting point as a new ACR default.
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Andrew Rodney
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Nick Rains
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« Reply #58 on: April 26, 2006, 06:10:22 PM »
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.....
My point is that there's no way to nice photographs without a system-immanent idea of color accuracy.  It’s hardwired deeply inside the input-pipeline starting with the sensor design.

Other people like Mr. Canon and Mr. ACR have already sorted this out for us behind the scenes (more or less). Even more, they already provide a first basic suggestion for a pleasing rendition on the top, output-referred, so that the user can focus on this last step to get everything ‘right’ within the limited dynamic range of the monitor and printer.
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[a href=\"index.php?act=findpost&pid=63753\"][{POST_SNAPBACK}][/a]

OK, I see what you're getting at, and I agree. Let me clarify my statements.

I feel that a pixel-peeping pursuit of pure accuracy is a flawed concept and will not lead to better pictures. Fujichrome was always a bit bright but it looked 'good' compared to Ektachrome which was arguably more accurate. Studio guys shot Ektachrome since they needed to match product colours, stock and landscape photographers shot Fuji because the colours looked better.

Having said that, as Bruce says, reasonably accurate colour is a necessary starting point but since it is such a hard thing to literally achieve, I rely on the camera to give me accurate enough colour and then I take it from there to the point which seems most satisfying. I have tried different methods to improve the basic colour response of the camera, ie calibration, and I have not found anything that meaningfully improves upon what the RAW converter is already able to do.

Which leads me back to the thread - plugins which base their approach on correcting real or imaginary inaccuracies in image capture are fighting an uphill battle. As Andrew pointed out earlier, once you define what you mean by 'accurate colour' you enter a very difficult region.

So, as long as Mr Canon has sold me a camera that gets me into the (small) ballpark I am happy. Somewhere in that ballpark is a distrubution of colours that I personally find appropriate and pleasing, whether or not those colours are strictly 'accurate' does not interest me.
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Nick Rains
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PeterLange
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« Reply #59 on: April 27, 2006, 06:12:20 AM »
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OK, I see what you're getting at, and I agree. Let me clarify my statements.

I feel that a pixel-peeping pursuit of pure accuracy is a flawed concept and will not lead to better pictures. Fujichrome was always a bit bright but it looked 'good' compared to Ektachrome which was arguably more accurate. Studio guys shot Ektachrome since they needed to match product colours, stock and landscape photographers shot Fuji because the colours looked better.

Having said that, as Bruce says, reasonably accurate colour is a necessary starting point but since it is such a hard thing to literally achieve, I rely on the camera to give me accurate enough colour and then I take it from there to the point which seems most satisfying. I have tried different methods to improve the basic colour response of the camera, ie calibration, and I have not found anything that meaningfully improves upon what the RAW converter is already able to do.

Nick,

Believe me, some problems on the way to get just nice photographs were the sole reason which brought me to all this technical stuff. Anyway, I hope that my posts did not damage the reputation of this discipline even more than some of the “science” which was offered related to the topic of this thread.

Referring to the term ‘reasonably accurate color’, it raises the fascinating question about the dosage of accuracy which a pleasing color should still contain. At the risk that it’s anytime possible to find examples for the opposite, I’d like to suggest a rule of thumb as follows:
Hue > Saturation >> Brightness.

Even a pleasing, output-referred rendition relies on a certain degree of Hue accuracy. Yes, there are tolerance ranges and a preferred reproduction of a specific color can involve hue shifts. But, my best guess is that strong memory colors such as skin tones are among the first who leave, if the camera + Raw converter fail to meet the hue of some related (red) patches on the ColorChecker chart.
Saturation seems to be of more volatile nature and pretty much subject of personal taste. Brightness can almost never be accurate due this whole subject of dynamic range compression (scene to output) and respective compensation measures (application of a sigmoidal tone curve).

So in full agreement with Bruce and Andrew that ‘reasonably accurate’ makes a better starting point - as well as in the sense that ‘options are good’ - let me refer to this former post here for some more details: http://www.adobeforums.com/cgi-bin/webx/.3bbf4d7a


P.S.:  Looking at your website and in particular the breathtaking online gallery, what could I ever tell you about image processing & pleasing rendition…

Peter

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