Re: RPP raw photo processor 64
Re: RPP raw photo processor 64
- Subject: Re: RPP raw photo processor 64
- From: Andrew Rodney <email@hidden>
- Date: Sun, 02 Jun 2013 12:08:12 -0600
On Jun 2, 2013, at 11:44 AM, Ben Goren <email@hidden> wrote:
> All cases? Don't be silly. Point the camera at the Sun and no print or monitor or what-not is going to reproduce the experience of looking at the Sun or even just of having it in your field of vision.
Or keep the lens cap on... No need to go into theoretical possibilities that few if anyone would attempt. Let's stick to good old pointing the camera at a scene we'd like to capture, view on-screen and print.
> But, in most typical non-problematic lighting conditions, yes, it's generally possible within the limits of the tools being used.
Ah, so along with using 'reasonable' to define this goal, there's additional limits of our tools. Like those that make ICC camera profiles or the targets we have access to?
> In the case of Dr. Berns's work, yes. The copy is practically indistinguishable from the original.
Output to what? Everything? An Epson wide gamut printer? An sRGB-like behaving display? They visually match or they numerically match (or both)?
> Here's the proverbial picture worth a thousand words. It's from this past spring, in the Superstition Mountains on the east side of the Valley of the Sun. The foreground is basically a colorimetric rendition. The sky was about a stop brighter than the foreground; I developed it separately and composited the two together (with a soft mask, not unlike a custom-shaped graduated neutral density filter). On reflection, I might have over-darkened the sky, but not excessively.
Worth a thousands words as it is a match from and two what? And on reflection, the sky needs to be darker so it's not colorimetric accuracy in action? The sky is colorimetrically too light or your memory of the scene suggests it's too dark? There's a difference.
> You'll have to take my word for it, of course, but, within the limits of the sRGB gamut (and many of the flowers lie outside of said gamut), this is a very, very close match to what I actually saw.
What is the colorimetric accuracy of the colors you recall you saw? Is there a time limit in terms of how long ago you saw that color and recall it matching?
> That constitutes colorimetric accuracy...for a ColorChecker. If all you're shooting are ColorCheckers, that's perfect.
I agree! It's exactly the failure I've seen over the decades trying to profile digital camera systems. In a controlled situation, it's possible. Then change a few parameters and you're back to fixing the image for pleasing (memory) colors.
> In practice, there are always going to be minor errors throughout the spectrum.
So what's the size of this colorimetric accuracy fudge factor? It's getting larger as we talk.
> But I'd also argue that it's analogous to a situation in which musicians didn't understand basic acoustics (including the relationship between frequency and pitch), but did understand when something was out of tune.
Again, this is an art, not a science as I would suggest Ludwig Van illustrated after he went deaf <g>.
> They want the ``pop'' of the Velveeta-like landscapes but with natural-looking skin tones and they don't want blocked shadows or blown highlights.
Which the ACR engine and plenty of other raw converters can provide. That pop they want that you illustrate prove my point that they don't want accuracty, they want pleasing color.
> Respectfully, your complaints indicate to me that you've never actually worked with a quality colorimetric workflow
Oh I've tried and in rare cases produced something close enough to make the client happy. But further, I'm trying to understand this idea of yours (and others) about the definition of quality colorimetric accuracy. I'm seeing a lot of areas where a fudge factor is being used making it difficult to accept what the term really means. When you starting suggesting that the final output (whatever that is) matches what you recall at the scene, now we're way out in left field in terms of defining this so called accuracy. What's the dE error's in your brain's memory of a scene you saw a week ago? What's the accuracy of your color perception, and under what physical and mental conditions? I'm all for a definition of actual, colorimetric accuracy. To me, that would indicate nothing perceptual but rather using some instrument to measure scene color and some output color. Otherwise, we are using personal interpretation and anyone can then say "this matches" while the other can say "no it doesn't". The moderator then has to say to each: Prove it.
> If I may be so bold, you yourself would seem to fit into this category, especially if your last attempts at implementing a colorimetric workflow were some time ago and with a 24-patch ColorChecker.
Depends on what you use that target for. And if you understand when it was designed and for what purpose. If your definition of colorimetric accuracy is capturing a 24 patch Macbeth, making a print that matches it visually on any number of output devices, that's doable and in fact Bruce illusrated this way back in 2004 in ACR! If someone suggests it's an ideal target for making ICC camera profiles, I'm on your side, it's not. It wasn't designed for it anyway. There were no DSLR's when the Macbeth was created yet the tool itself is useful in some situations. The only bad reputation it has is from people who don't use it correctly or for what it was designed for. This is why a don't complain that a kitchen knife makes a poor screwdriver.
Andrew Rodney
http://www.digitaldog.net/
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