Are these statements about the Pro Photo color space true?

[Edalongthepacific]

1. There is an advantage in converting sRGB files to ProPhoto in Photoshop as, even though you won't get additional colors, adjustments such as saturation will have a larger range of colors to work with when using the ProPhoto color space.

2. Canon and Nikon RAW files (CR2/NEF) are not confined within the sRGB or Adobe RGB color space options of a digital camera. They have a color space closer to the ProPhoto color space.

3. No monitor known to mankind can produce even 85% of the visible colors of the ProPhoto color space.

4. Many advanced "photo" style inkjet printers using 12 or 13 inks can print colors found only within the ProPhoto color space.

[Schewe]

#1 Not really, if you've captured into or transformed into sRGB, you've cut those colors that existed in the camera out. You can't regain them just by going to PP RGB. and editing the colors by slamming the saturation won't be optimal. Once gone, they really are gone–it's far better to start in PP RGB.

#2 true for the first part, not really for the second part. PP RGB is the only color space in ACR or LR that can contain the colors your camera can capture but the camera color space and PP RGB are very different.

#3 correct, heck, about 13% of the colors in PP RGB aren't even real colors they are imaginary for the purposes of containing the real colors.

#4 Sorta...high-end printers can indeed print colors outside of the gamut of sRGB or ARGB but there are other color spaces that may be able to contain those colors. However, it's moot since in ACR and LR, PP RGB is the only color space that maintain the camera color gamut.

#5 If you are going to use PP RGB, be sure to do post in 16 bit/channel or above (you didn't ask that but I answered anyway).

[MarkM]

Well #1 actually is actually true. After converting to from sRGB to PP RGB the saturation controls will be able to push the colors beyond the original sRGB gamut. Whether you're going to like the results of that is, or course, a different question. You'll be artificially creating colors rather than regaining lost information.  So Schewe is also right—you're better of starting with PP RGB in the first place.

[Tim Lookingbill]

Edits will look slightly different when performed in Photoshop depending on the tool used and color space applied in.

In the sample screenshot of my print test target below the top source sRGB version that includes a linear looking grayramp was lightened by entering 1.15 in the middle slider in Photoshop's Levels.

Prior to this a duplicate of the sRGB version was made and converted to ProPhotoRGB where I applied the same Levels edit. Note the lighter looking gray patch next to black in the ProPhotoRGB version evidenced in the DigitalColor Meter RGB readout differences between the two.

That's about the only differences you're going to see "editing" in these spaces.

[MarkM]

That's about the only differences you're going to see "editing" in these spaces.

That's not my experience. You can get dramatic differences between these two spaces when performing edits, especially when you apply saturation controls to the images.

[digitaldog]

Well #1 actually is actually true. After converting to from sRGB to PP RGB the saturation controls will be able to push the colors beyond the original sRGB gamut.

True but it is like starting with a pint of water and then throwing that into a gallon container only to add a pint of oil. The container is larger yes, but what you fill later isn’t very useful or drinkable. Heck, you can open a document in sRGB from the get go, crank up saturation and extend the gamut of a lot of colors (within the container size) but the results are usually butt ugly.

[Tony Jay]

Others may disagree but I can't see the point of shooting using sRGB unless that image will only ever be displayed electronically and little or no post-processing is envisaged.

Shoot with adobeRGB, edit in the PPRGB in Lr, Ps or whatever, then use sRGB as an export colour space if the image is to be displayed electronically only.

Regards

Tony Jay

[Tim Lookingbill]

That's not my experience. You can get dramatic differences between these two spaces when performing edits, especially when you apply saturation controls to the images.

I agree with you, Mark. That's why I included the "about" in my statement. However, I've found for the best pushing of saturation working in ProPhotoRGB coming from sRGB is to apply the edits in 16 bit linear ProPhotoRGB in ACR/LR instead of 1.8 gamma ProPhotoRGB which I have ACR set as output space.

You'll notice my little gray patch demonstration opens up shadows when applying a simple gamma style adjustment in Levels. This is pretty much how it behaves but even more so in linear ProPhotoRGB in ACR/LR.

Just to confirm but from my foggy memory on this subject when it was asked, I understand all jpeg and tiff data (no matter their gamma encoded color space) are being converted to this linear space when opened in ACR/LR, right?

[MarkM]

Just to confirm but from my foggy memory on this subject when it was asked, I understand all jpeg and tiff data (no matter their gamma encoded color space) are being converted to this linear space when opened in ACR/LR, right?

I don't know what ACR/LR does with tiffs and jpegs. I don't really use LR this way, but I think it's an interesting question.

the results are usually butt ugly.

I don't think anyone here would disagree with that.

[Schewe]

Just to confirm but from my foggy memory on this subject when it was asked, I understand all jpeg and tiff data (no matter their gamma encoded color space) are being converted to this linear space when opened in ACR/LR, right?

Yes...more or less. All of the processing is done in PP RGB colors in linear but, there are other excursions in there that are HSL as well. But processing JPEGs in ACR or LR is better than trying to convert sRGB to 16 bit PP RGB in Photoshop for editing...

[Tim Lookingbill]

Thanks for the confirmation, Jeff.

Now I know why I like editing in ACR instead of Photoshop even for jpegs and tiffs.

[Nora_nor]

Lightroom is said to use something called Melissa colour space which is different from ProPhoto

http://sites.google.com/site/chromasoft/icmprofiles

[digitaldog]

Lightroom is said to use something called Melissa colour space which is different from ProPhoto

The RGB primaries are the same. The gamma encoding is different from ProPhoto RGB. And it isn’t really useful other than showing you numeric values outside of LR.'s soft proofing and it’s histogram. It isn’t the processing color space and for most, it isn’t the output color space (although it is possible to use if you have that profile loaded on your system. I don’t know why you’d do that).

[Schewe]

Lightroom is said to use something called Melissa colour space which is different from ProPhoto

Melissa RGB is ProPhoto RGB colors with an sRGB tone curve and the ONLY place you find it is in the Develop RGB readouts and the histogram plot. It's not used as a processing workspace in the ACR/LR pipeline, that's PP RGB and a linear gamma.