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Let's say I've loaded my print shop's ICC profile for the printer/paper/ink combination I'll be using into Lightroom, I've soft-proofed the image in the Developer module with said ICC profile, and I'm ready to export to JPG before sending to my print shop. What embedded color profile do I want in my JPG?

My rationale says that I want to embed Prophoto RGB into the JPG because that is what Lightroom uses as its color space, and since the soft-proof is a conversion between the the ICC profile and my color space, I need to embed my color space to ensure my soft-proofing work remains true after I export - to keep an apples-to-apples comparison.

Am I making false assumptions or applying some false logic, or do I understand the workflow correctly?

Thanks!

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You need to export to one of whatever various color profiles your print shop can use and embed the profile you actually designated in your export settings. The vast majority of print shops can handle sRGB, Adobe sRGB, and various CMYK based profiles. If they can handle Prophoto RGB (ROMM - Reference Output Medium Metric) then you can use that, too.

But in most cases it isn't really going to make much difference in the end. When you loaded the printer/ink/paper's color profile onto LR, LR limited itself to only using the colors that the profile said that particular printer/ink/paper combination is capable of reproducing. If all of those colors fall within sRGB then there will be very little, if any, difference in using a wider colorspace to export the image. If all of those colors fall within Adobe RGB then there will be very little, if any, difference in using a wider color space than Adobe RGB to export the image.

In fact, depending on the contents of the image, you could have smoother transitions for tones and hues by using the smaller colorspace, which has less 'distance' between each discrete value at the same bit-depth than a larger color space will have. Theoretically, your best result would be to use the smallest color space that includes all of the colors the printer/ink/paper profile allows.

The other question you must answer is what colorspace your monitor is using. Just because LR uses ROMM internally does not mean you are seeing the image on your monitor in ROMM. If your monitor is a standard sRGB (or Adobe RGB) monitor, the internal ROMM image is already being translated into sRGB (or Adobe RGB) before you're seeing it as you are editing.

We can all view the following CIE 1931 chart showing the Prophoto RGB (ROMM) color space on whatever monitor we are using. But if the monitor is not capable of showing the full gamut of ROMM colors, the colors we're seeing on the chart are not the actual colors at each location within ROMM. Even if we did have a monitor capable of displaying ROMM, if the chart was saved and properly tagged in sRGB, all of the colors displayed are going to fall within the sRGB color space. The differences between colors within the sRGB space and those outside the sRGB space are simulated. All of the colors displayed actually fall inside sRGB.

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  • \$\begingroup\$ "LR limited the Prophoto RGB colorspace to only using the colors that the profile said that particular printer/ink/paper combination is capable of reproducing"... This doesn't make much sense to me. You are either using ProPhoto RGB or you are not using ProPhoto RGB. There's no such thing as a limited version of ProPhoto RGB. That would be a different colour space. \$\endgroup\$
    – osullic
    Dec 22, 2017 at 16:50
  • \$\begingroup\$ @osullic What it means is that only colors contained within the profile are being used. Other colors within the ROMM colorspace that can not be reproduced in the profile are being transformed to colors, using the ROMM colorspace model, that can be reproduced by the printer/ink/paper. The colors displayed are limited to those that can be reproduced by the printing system. \$\endgroup\$
    – Michael C
    Dec 22, 2017 at 17:04
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I should say that I am not familiar with Lightroom, but I am familiar with colour management.

What you should do is edit your images in a "device-independent" working space, such as ProPhoto RGB. You can use soft-proofing (which I think you are doing) to visualise the final output in your print shop's profile. It should go without saying that you need to use a calibrated monitor - calibrated using a hardware calibration device, such as those from Datacolor or X-Rite.

As a final step in your editing workflow, you convert the image from ProPhoto RGB to your print shop's profile, and export as JPEG with that (print shop) profile embedded.

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  • \$\begingroup\$ Can you clarify "export with that print shop's profile embedded?" You're not referring to their ICC printer profile, but rather whatever color space profiles they can accept (e.g. Adobe RGB, sRGB, etc.), yes? \$\endgroup\$
    – the_meter413
    Dec 23, 2017 at 20:19
  • \$\begingroup\$ An ICC profile defines a colour space. If you convert to and export in this colour space, your image will be in a colour space that the printer can accept, by definition. If you export as, say, Adobe RGB, then at some point at the print shop, your image will be converted to the colour space defined by the printer profile. But exporting your image already converted means you have handled this step yourself. \$\endgroup\$
    – osullic
    Dec 23, 2017 at 22:11
  • \$\begingroup\$ You can equally export the image as ProPhoto RGB, as long as it's an acceptable colour space for the print shop. As I said, at some point, your image will be converted to the colour space as defined by the ICC profile. But if you have soft-proofed to your satisfaction, then it shouldn't really be an issue. \$\endgroup\$
    – osullic
    Dec 23, 2017 at 22:17

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