Raw file colour space - only sRGB?

[Mike Rawcs]

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I've just read a review of the T that states that the DNG files only use sRGB colour space and that Adobe RGB is not an option. Is this the case?

 

Mike.

[pico]

I've just read a review of the T that states that the DNG files only use sRGB colour space and that Adobe RGB is not an option. Is this the case?

 

Mike.

 

I would be interested in reading that review.

 

To the best of my knowledge, sRGB is used in the color preview only.

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[jip]

RAW is neither sRGB or Adobe RGB...

 

It's RAW...

 

depends on your editor how you export it

[jaapv]

DNG has indeed no colour space, being a raw format. Only the embedded thumbnail is sRGB, but that is neither here nor there.

I normally develop the DNG to ProPhoto, and so does Lightroom.

 

What review was that?

[Mike Rawcs]

Thanks for the replies. the review is here....

 

Leica T (Typ 701) - Photo Review

 

The reference is in the 'What's missing' section.

 

Perhaps it refers to jpegs?

 

Mike.

[Mike Rawcs]

The M240 manual shows ...

WORKING COLOR SPACE

The requirements in terms of color reproduction differ considerably

for the various possible uses of digital picture files. Different color

spaces have therefore been developed, such as the standard RGB

(red/green/blue) that is perfectly adequate for simple printing. For

more demanding image processing using appropriate software, e.g.

for color correction, Adobe˝ RGB has become established as the

standard in the relevant sectors.

Setting the function

1. In the main menu (see p. 154/246) select Color Space

(page 2, IMAGE section), and

2. Select the desired function in the sub-menu.

Notes:

• If you want to have your prints produced by major photographic

laboratories, mini labs or Internet picture services, you should

select the sRGB setting.

• The Adobe RGB setting is only recommended for professional

image processing in completely color-calibrated working

environments

 

I can't find a corresponding page in the T manual.

 

Any clarification welcome.

 

Jip, my interpretation of how the colour space works is that it affects the colour gamut that is captured. Adobe RGB will capture a wider range of colour shades than sRGB and therefore affects the Raw file. How important this is, I don't know. If sRGB is recommended for printing, what is the advantage of capturing with an Adobe RGB colour space?

 

Mike.

[pico]

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Thanks for the replies. the review is here....

 

Leica T (Typ 701) - Photo Review

 

The reference is in the 'What's missing' section.

 

"Users of the T also get no choice of colour spaces; it's sRGB only. This probably won't matter to most potential purchasers but there are plenty of serious photographers who prefer the wider gamut that Adobe RGB provides, particularly for landscape photography."

 

The author is wrong.

 

[Mike Rawcs]

Thanks Pico. How do you know? I can't seem to find anything about the Ts colour space.

 

Mike.

[pico]

Jip, my interpretation of how the colour space works is that it affects the colour gamut that is captured. Adobe RGB will capture a wider range of colour shades than sRGB and therefore affects the Raw file.

 

Range of color shades is 'gamut'. It does not effect the raw data. It effects the output you choose.

 

That said, to date most printers are designed to the sRGB gamut. Some professional (high-end) printers can handle the gamut of Adobe RGB.

 

What Mike referred to is a menu option. It sets a code in the raw data to treat the data as RGB or sRGB in processing. I'm pretty sure it is just a handy default that can be changed in the processing software's options. In my opinion, it's a confusing and makes sense only to someone who does almost exclusively RGB printing.

Edited February 16, 2015 by pico

[adan]

The difference between a raw file (i.e. DNG, NEF, CRF, RWL.... most manufacturers has different raw file extenstions, but they all mean "raw") and a jpeg file is that raw files are simply grayscale data - how much light, total, hit each pixel on the sensor. From none (black) to white.

 

Until the raw file is decoded through a raw converter, or image program that has a raw converter - it is simply brightness levels, not colors. Although it contains information that can be used to determine colors, by way of knowing which pixels had red Bayer filtering, which had green, and which blue.

 

Raw files are somewhat like the B&W separation negatives in the top row of this diagram - they are monochrome brightness maps: http://www.sirspeedystpete.com/images/4ColorSeparation.jpg

 

There is no "color" to map to a color space, so neither a way to, or a need to, assign a color space for a raw file.

 

When you open a raw file with your computer, at that moment (and not before) you decide which color space to create the colors in, usually through the preferences you defined for your imaging program. Your software turns the raw numerical light/dark values into a color picture at that point.

 

A jpeg goes through the color decoding process while still in the camera, to create a finished picture. Therefore you need to choose a color space - in camera - for shooting jpegs.

 

It may well be that - FOR JPEGS - the T offers no choice for choosing an in-camera color space - it may well use only sRGB. But that will have no meaning for raw DNG pictures, which do not have a color space until you start handling the picture yourself at the computer.

 

As to what a color space is, and the difference between Adobe 1998 and sRGB:

 

There is a "global" color map of all possible colors, called CIE 1931 or CIE xyz: CIE 1931 color space - Wikipedia, the free encyclopedia

 

All other color spaces are subsets of that global space. Adobe 1998 is a larger subset than sRGB - it includes some colors not included in sRGB (mostly in the saturated intense greens, cyans and blues).

 

Think of the global CIE color map as "the world" - in which Adobe 1998 is "the United States" and sRGB is "Texas."

 

It's important to note that an 8-bit RGB jpeg contains ~17 million colors (256 x 256 x 256 values for R, G and - REGARDLESS of the color space used. An sRGB jpg will contain a different set of 17 million colors than the 17 million in an Adobe 1998 jpg - but they both contain 17 million, spread over slightly different parts of the CIE 1931 master map of colors.

 

(The reason being - of course - that there are a infinite number of colors in the master map. Pick any two colors, and no matter how close they are on the map, another color can be found in between them.)

 

Another point to clarify:

 

Devices (cameras, printers, inks, scanners) do not have color spaces - they have "gamuts." The range of colors they can record or reproduce. If you try to photograph a red outside the gamut of a given camera, it will be recorded - but shifted in hue or saturation to the nearest in-gamut red (i.e. recorded inaccurately). Same for printing - send you printer a blue outside its gamut, and it will print its best approximation of that blue within the gamut its inks can handle (an innaccurate approximation of the real blue).

 

Files are defined in terms of color spaces, and one can talk about the gamut of a color space - its borders within the master set of colors - as just ONE of the characteristics of a Color Space (other characteristics include white point, black point, etc.). As with devices, colors outside the gamut of a color space get transformed (numerically and visually) into the nearest in-gamut color when a color space is defined for an image.

 

So a gamut and a color space are two different things.

[pico]

Andy Piper, Think of the global CIE color map as "the world" - in which Adobe 1998 is "the United States" and sRGB is "Texas."

I love it. A great mnemonic. I laughed in appreciation.

 

To expand a bit on the interpretation of raw data, there are methods in the DNG standard to accommodate methods that do not look for a Bayer array, for example the Fovean sensor, and tri-color sensors.

--

Pico who is from the gamut impoverished state of Rhode Island.

Edited February 17, 2015 by pico

[Mike Rawcs]

Thank you Andy and Pico.

 

Mike.

[bernie.lcf]

Leica's Maike Harberts has explained in an interview (about the process of designing the Leica T) that the choice of color space was left out by design. Her point was that this is a hardly used feature and causes more harm than benefit.