Color Space - Shooting and Editing

Started 3 months ago | Discussions thread
Iliah Borg Forum Pro • Posts: 27,578
Re: Color Space - Shooting and Editing
4

Ernie Misner wrote:

Kaj E wrote:

Sagittarius wrote:

Flyer4Ever wrote:

Hi everyone,

I'm aware of the differences and limitations of the 3 color spaces: sRGB, Adobe RGB and ProPhoto RGB but in order to be editing in the higher color spaces, do we also need to shoot in Adobe RGB?

Currently I am shooting in sRGB but after importing into LR, I export to Photoshop in ProPhoto RGB and save as PSD. Once I'm happy with the result, I'll export to jpg and convert to sRGB to display on web.

I'm curious if I need to shoot in Adobe RGB from the very beginning in order to preserve the color space. Or can I continue shooting in sRGB and exporting to PS as ProPhoto RGB and then convert to sRGB for web? I'm also confused how it's possible to convert my sRGB RAW to ProPhoto RGB PSD if I didn't shoot in a wider color space to begin with..

Thanks in advance!

If you shoot in RAW, it does not matter what color space you shoot in. RAW file can be opened in any color space. When you convert it to another format, than you can choose color space.

The advantage of shooting in Adobe RGB is that the wider gamut of the embedded image which is used for the display of the histogram in camera is more useful than the sRGB histogram. If you shoot sRGB the camera histogram shows clipping when there is none when you edit in a wider gamut.

We all (raw shooters) desire a true raw histogram, so shooting in AdobeRGB gets us one step closer to that it sounds like? Have you done an in-camera test where you shoot the same scene twice with the camera set to sRGB for one shot and AdobeRGB for the second shot, and then compared how much different the histogram is between the two? Or would that even work?
Also do you set your picture mode to neutral rather then landscape or vivid to get a more (or less) accurate histogram for your raw file? Thanks.

Look at a sensor as at a collection of millions of exposure meters, each being covered with some wide-band colour filter - because that's what a sensor effectively is. What's the output of such an array? It's exposure information. How do we go from exposure information to colour information? - we need to convert. Is this conversion unambiguous? - generally, no.

Why is it ambiguous? - for example, because of different metamerism issues. The approach to analyzing issues caused by metamerism can be found in "Measuring Colour" by R.W.G. Hunt and M.R. Pointer, 4th Edition, Chapter 6, "Metamerism and Colour Constancy", of specific interest is the presentation in 6.17, "Worked Examples".

You can extrapolate those metamerism issues the chapter explains to sensors, adding an issue that arises from sensor adding illuminant-depending metameric error of its own; which will lead to Chapter 12, "Colorimetry with Digital Cameras", and specifically to 12.3, "Metamerism" and 12.5, "Practical Considerations In Digital Camera Characterisation".

Common raw files (same as a scanner output) are in a device space which isn't colorimetric. This device space is exposure-based, while input colour profiles are essentially functions that convert raw data numbers from exposure space to colorimetric space. Because the exposure space is not colorimetric, for each device a multitude of such functions exists.

Further, input colour profiles determine the initial "look" of the render, and even if an unambiguous colorimetric colour transform from the device space to a colorimetric space exists, one can (and often does) prefer non-colorimetric look (including opting for artistic white balance). Capture files not meant for reproduction are nearly always open to artistic interpretation.

Incidentally, the two paragraphs right above this one suggest that different profiling tools and different users may prefer different "looks" as the standard.

"True raw histogram" can't use an ambiguous conversion that input colour profiles offer, and it's not about how raw data looks to an eye after it has being rendered through a profile and clipped by a tone curve. True raw histogram should "expose" the exposure space directly.

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