Prophoto in NIK, sRGB on export. Problem?

[Downrigger]

I struggle with color space concepts.

It seems that after RAW processing in Lightroom that the Nik softwares take up the image in prophoto color space. After the images return to LR, as Tiff files and with or without additional LR tweaks, I have been exporting them as JPEGs for print or screen in sRGB, a "smaller" color space, as I understand it. This must toss out or modify some of the color information in the Tiff, and I don't know if this is consequential in a minor, or major way.

Should I just stay in prophoto for export? Why, or why not, or does it really matter?

Thanks in advance for any education on this.

[Manfred M]

Mark - it depends on what you do with the image. Anything displayed on the internet is sRGB, so if you post in one of the wide gamut colour spaces like AdobeRBG, ProPhoto, etc will come out looking dull and muddy when you view a file in the web browser. This has to do with how the colours are mapped; as all colour spaces represent values as RGB values, but each colour space will not have the same value for the same colour (i.e. (0,255,255)) will not look the same,even though the same integer values are used to describe a colour.

I use ProPhoto as my default colour space and convert to sRGB before posting. I have a wide gamut monitor that convers most of the AdobeRBG color space.

While there are potential losses in colours, these tend to primarily be in the brilliant greens and brilliant blues. It really depends on the colours in your image, so the impact is often not noticeable in a lot of shots unless they have those neon greens or electric blue tones.

[Downrigger]

Thanks, Manfred. That helps.
So, am I right that when you convert from prophoto to sRGB, your conversion takes to sRGB only the R/G/B values from prophoto that have a location in sRGB? However when you post prophoto on the internet, the R/G/B values in prophoto that lie outside sRGB's range are somehow included in the internet image by virtue of compression, hence loss of fidelity and muddiness?

[Manfred M]

When you convert; the software algorithms will map in-gamut colours correctly and out of gamut colors as best as it can.

If you do not map, whether it be a commercial photo printer or the internet, the receiving software will assume the data is sRGB and apply the numeric values directly, and incorrectly. Because the wide gamut colour spaces have more brilliant colours at the extremities; using the intermediate values means colours that are relatively brilliant in sRGB will be mapped to duller versions. This is not necessarily linked to compression, but I suspect that this could take a bad situation and make it worse.

[PhotomanJohn]

Mark - How the out of gamut colors are mapped into the new color space is a function of the rendering intent you select for the conversion. There is a good tutorial under Color Management and Printing called Color Space Conversion that should help you out.

John

[DanK]

Mark - How the out of gamut colors are mapped into the new color space is a function of the rendering intent you select for the conversion. There is a good tutorial under Color Management and Printing called Color Space Conversion that should help you out.

John

It's necessary to distinguish between exporting for print and for display on the web. At least as far as I know, LR gives the choice between relative and perceptual rendering only for printing. You actually don't need to export at all for this. You can leave the file in prophoto, and when you go to the print module or the softproofing module, it will give you the choice between the two renderings for the color space of the combination of printer and paper you have chosen. However, when exporting as a jpeg for the web, I haven't noticed that choice in the export dialog. It just asks for a color space. Am I missing something?

[Downrigger]

It just asks for a color space. Am I missing something?

I don't think so - that's the way it looks to me. So I'm guessing there's a default rendering (which?) in LR for whatever color space you choose for image export.
I don't print so wouldn't know if there's a rendering option in the print menu.

[PhotomanJohn]

It's necessary to distinguish between exporting for print and for display on the web. At least as far as I know, LR gives the choice between relative and perceptual rendering only for printing. You actually don't need to export at all for this. You can leave the file in prophoto, and when you go to the print module or the softproofing module, it will give you the choice between the two renderings for the color space of the combination of printer and paper you have chosen. However, when exporting as a jpeg for the web, I haven't noticed that choice in the export dialog. It just asks for a color space. Am I missing something?

Dan - That is an interesting comment about Lightroom. I am primarily a Photoshop user where one converts the color space before the file is converted to jpg or other file format. This is done under the edit menu using the Convert to Profile command which asks for the rendering intent to use. There must be an equivalent way to do it in Lightroom.

Edit: A little web research says there is not a way to do it in Lightroom. Differing views say it would be of no value where others say that Lightroom designers just wanted to make it simpler.

John

[Downrigger]

In LR5, in soft proofing, you can see the areas lost/altered on your image according to color space and rendering intent. I notice that sometimes it's a lot! I just can't see where the choice rendering intent (perceptual vs. relative) is an option when exporting a file.

[DanK]

In LR5, in soft proofing, you can see the areas lost/altered on your image according to color space and rendering intent. I notice that sometimes it's a lot! I just can't see where the choice rendering intent (perceptual vs. relative) is an option when exporting a file.

I couldn't find it in the export dialog either, but it is in the print module, very near the bottom of the right-hand panel, in the section where you select a profile, etc.

[davidedric]

Maybe this is because when you soft proof in Lightroom you are proofing against defined printer and monitor profiles, hence the software can show the out of gamut colours for either, and you can judge which rendering intent you prefer. When you export to a file you have no idea of the destination device, so giving a choice of rendering intent wouldn't make a lot of sense. ??

Dave

[Manfred M]

In LR5, in soft proofing, you can see the areas lost/altered on your image according to color space and rendering intent. I notice that sometimes it's a lot! I just can't see where the choice rendering intent (perceptual vs. relative) is an option when exporting a file.

Rendering intent is really a printing parameter; we have to map a RGB image to a CMYK device, so additional information is needed in the translation process. The different colour spaces used on screens are also about mapping, but more about how a three digit RGB value is mapped to a specific colour.

To give an extreme example; a PowerPoint presentation or vector graphics drawing will tend to go for "crunchy" colours whereas an photographic image is all about tonal subtleties. For the photo, I would go perceptual and for the graphics I would go relative. Just to complicate issues (and also because it is used for far more than photo editing), Photoshop has four different rendiering intents; Perceptual, Absolute Colormetric, Saturation and Relative Colormetric.

There is no value in adding rendering intent in a file; that is a decision that impacts the printed output only.

[Downrigger]

This is all very helpful. I have learned a good deal about this. Thank you Manfred, Dave, Dan, John et al.

So... as I understand it:

1. Exporting TIFFs or dngs from LR (which are more or less in a prophoto space) for web display as Jpegs in sRGB is therefore done with some default algorithm/rendering intent (one does wonder what it is), and the soft proofing module can't help me to see what is being altered or lost in those exports. I am just meant to keep my device calibrated and assume the best.

2. When I export to make files for the specialty shop that does my printing, I assume it best send them files in Prophoto, as worked, and let them take it from there.

[Manfred M]

When I export to make files for the specialty shop that does my printing, I assume it best send them files in Prophoto, as worked, and let them take it from there.

Mark - this is a very bad assumption; most print shops, includiing many of the higher end custom ones work sRGB only.

I do ask and I will tend to deal with ones that do provide me with ICC profiles for the printers and papers that they do use. It is safest to do the conversion to sRGB yourself before sending the image off for printing.

[Downrigger]

Thanks, Manfred - I do intend to ask what works for the shop I use - now that I know a little more about what I am asking for, thanks to this thread. They are a custom shop, so I assume they work in a larger gamut than sRGB, wouldn't that be true of better custom printers?

[Manfred M]

Thanks, Manfred - I do intend to ask what works for the shop I use - now that I know a little more about what I am asking for, thanks to this thread. They are a custom shop, so I assume they work in a larger gamut than sRGB, wouldn't that be true of better custom printers?

I would ask, but assume in general that they don't.

I've run into a couple of shops that do AdobeRGB, but none that handle ProPhoto. One of the shops did their own converstion from AbobeRGB to sRGB; which is okay; at least they understood the need to pay attention to the embedded colour space, rather than assuming that it is sRGB.

I prefer doing that myself as I have had to tweak the image after I changed colour spaces. On the other hand, I tend to do my own printing and will only go to a custom shop when I have large quantities or want a print that is larger than what my printer can handle.