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Author Topic: Yet One More ProPhoto RGB Query  (Read 2047 times)

JimAscher

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Yet One More ProPhoto RGB Query
« on: March 01, 2011, 08:27:09 am »

There is so much good material in this forum concerning the merits of employing ProPhoto RGB, but a search on my part has failed (for me) to answer the following query, which I will preface with a quote from Vincente Versace's 2011 update of his book "Welcome to Oz 2.0."

His page eight, with a heading "Setting Up Photoshop for a Non-Destructive Workflow," discusses the relative merits of ProPhoto, sRGB, and Adobe RGB.

He then has a separate "NOTE" on the page which reads as follows"

"Once you capture in or convert into a smaller color space, all you have are the colors of that space.  So if you have been converting your sRGB captured files into ProPhoto RGB thinking that you have maximized the gamut of color, what you really have done is similar to pouring a quart of water into a gallon container; it is still only a quart of water."

The use of the words "capture' and "captured' in the above quote are what concern (and puzzle) me.  My cameras only have the options of designating as color space sRGB and Adobe RGB.  Does this therefore mean, according to my understanding of Versace's NOTE, that any attempted use of ProPhoto RGB in my Lightroom or Photoshop processing is of no real benefit because of the inherent limitations of my cameras' color "captures" in either sRGB or Adobe RGB?

Is this really so?  Or am I -- one again! -- confused.
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digitaldog

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Re: Yet One More ProPhoto RGB Query
« Reply #1 on: March 01, 2011, 08:34:25 am »

If you shoot raw, you can process and encode in virtually any RGB color space a converter supports, when you shoot JPEG, the settings on the camera provide (for most cameras), sRGB or Adobe RGB (1998).
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howardm

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Re: Yet One More ProPhoto RGB Query
« Reply #2 on: March 01, 2011, 09:37:52 am »

it's one of the more confusing things the camera manuals don't make clear in that the s/aRGB setting only affects non-raw capture and also that the image you see on the LCD is the processed jpg thumbnail.

JimAscher

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Re: Yet One More ProPhoto RGB Query
« Reply #3 on: March 01, 2011, 09:47:09 am »

Ah, that REASSURES me, as I do only shoot in RAW.  Yes, it IS confusing, that the camera manuals don't clarify this actual effect of an in-camera color designation.  Thanks, guys.
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Tim Lookingbill

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Re: Yet One More ProPhoto RGB Query
« Reply #4 on: March 01, 2011, 12:49:33 pm »

How do you know what the camera captured? Can you prove it?

A digital camera filters photons into RGGB buckets called pixel sites that get turned into voltage readouts by your camera's electronics which get converted into 1's and 0's by a high bit Analog to Digital converter. Technically your camera records black, white, gray level relationships between pixels.

The Raw converter and display gamut really determines what these gray pixel variations and relationships look like on a computer. COLOR RELATIONSHIP is an important aspect of reconstructing what those pixels look like because of optical effects that can occur editing color on a transmissive display.

For instance is the green seen that hue of green because the surrounding pixels are a certain shade of a complimentary color like red or red orange? You've heard of an image having a color "patina"? It's the overall color subtleties that produce this. Saturation levels and different hue transitions can trick the eyes into seeing color a certain way. There's a lot of complicated optical phenomenon that occur when reconstructing an image on a transmissive display especially during edits. ProPhotoRGB allows coaxing of these color subtleties and patina's especially on a wide gamut display over any other color space. I've seen it for myself.

I have shot flowers and other vibrant objects that I couldn't reproduce in any other color space but ProPhotoRGB only limited by the gamut of monitor. There are some inkjet printers that can deliver a reasonable facsimile of these hue relationships, color subtleties and patina's. If you don't shoot vibrant colored objects then ProPhotoRGB isn't necessary, but it doesn't hurt either.

Working in ProPhotoRGB also renders a more manageable looking histogram in ACR on some high contrast shots taken outdoors that gives me a huge amount of headroom in my edits in a more systematic approach (i.e. adjusting endpoints on the Linear point curve is more linear than the Exposure slider on some images. Try it. It'll make you look at the image in a different way you hadn't seen before).

Of course if all you shoot is fashion shots in a light controlled studio then AdobeRGB will suffice.
« Last Edit: March 01, 2011, 01:00:48 pm by tlooknbill »
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