Unexpected result after converting image profile to softproof profile

[Mark D Segal]

Mark, could you talk a little bit more about "Preserve RGB Numbers" is used for and what it actually does?  It looks to me like it shows a preview of the transformation without a rendering intent.  Are you saying that a commercial printing service would print without applying a rendering intent, and that we should re-adjust the image with a curve to apply a rendering intent by eye?  I'm not trying to make an argument here, just trying to learn about this

Typically, one does not use this setting for soft-proofing, except in the case of sending photos to an outside lab for printing. If the lab specifies the colour space (which you use for this purpose)  and the lab provides their printer/paper profile, when you use this for soft-proofing, by checking Preserve RGB numbers it will simulate what the print will look like if you send those RGB numbers to that profiling combination.

It's often considered best practice to edit the photo using a colour working space (ARGB etc) before doing conversions to printing lab profiles. You can softproof for Rendering Intent and in the case of Relative whether or not to use BPC as well (usually recommended to use it).

However, when you convert, which should be one of the last steps in your preparation procedure, you are presented the choice of Rendering Intent and for Relative Colorimetric Intent,  whether to also use BPC. The choice between these Rendering Intents is a matter of taste. It's what makes the photo look better. If you choose Perceptual there is no option to select BPC because it's supposed to include for that adjustment internally. If you choose Relative, it's usually best to also use BPC as it will help maintain shadow detail. Once the photo is converted, it is of course purposed to that printing set-up, and you may wish to amend some of the edits already done. Perhaps best to use a duplicate photo or keep it all on Adjustment Layers so the photo can be easily repurposed down the road.

[digitaldog]

The Preserve RGB options are not useful really. It shows a soft proof of what you would get if you sent the image to the output device with out the print profile which is rather ugly.

[Mark D Segal]

The Preserve RGB options are not useful really. It shows a soft proof of what you would get if you sent the image to the output device with out the print profile which is rather ugly.

Not useful in general, but according to Tom, in the specific case of preparing the photos for a service bureau who tells you the colour working space and gives you their printer profile, it's useful for predicting, under softproof, what will come out of their printer - which in that particular case would seem to be useful.

[digitaldog]

Not useful in general, but according to Tom, in the specific case of preparing the photos for a service bureau who tells you the colour working space and gives you their printer profile, it's useful for predicting, under softproof, what will come out of their printer - which in that particular case would seem to be useful.

Nope. More useful I CMYK workflows with EXISTING CMYK (what does this CMYK look like on THAT CMYK device)

[Doug Gray]

Typically, one does not use this setting for soft-proofing, except in the case of sending photos to an outside lab for printing. If the lab specifies the colour space (which you use for this purpose)  and the lab provides their printer/paper profile, when you use this for soft-proofing, by checking Preserve RGB numbers it will simulate what the print will look like if you send those RGB numbers to that profiling combination.

Mark's last two three posts are comprehensive and accurate. I would like to add why "Preserve Color Numbers" exists in the soft proof menu because it's due to variations in how Photoshop otherwise shows an image after it has been converted to a printer's RGB device space.

After conversion, an image may, or may not, accurately show what it will look like when printed. This is because, after conversion, Photoshop doesn't know (or forgets - it could track this with metadata) what Intent the conversion was done with or whether BPC had been selected so it uses the default settings in the "Color Settings Menu" for display purposes.

Soft proofing with "Preserve Color Numbers" is their way of showing you what the print will look like. When selected the only option you have is to select are "Show Paper Color" or not. If not selected Photoshop will use the printer profile to show colors based on a Relative Colorimetric interpretation. If selected, it will show colors based on Absolute Colorimetric which will slightly reduce luminance and slightly shift the tint to align with the intrinsic tint that would be printed. This avoids variations that occur based on the default settings in "Color Settings" because how the printed image will appear at that point should not be subject to the vagaries of whether it should be corrected for BPC or Perceptual which might have been selected.

This is what happens behind the scenes. If you don't select "Show Paper Color" it will show the same image as if you had done a "Convert Profile" selecting Relative Colorimetric and not BPC to a standard RGB space that encompasses its gamut. When selected, it will show the same as if you had converted using Absolute Colorimetric. Once converted to a standard RGB space these images are not affected by the "Color Settings" Intent and BPC settings. So the "Preserve Color Numbers" is just a quick way to see a proof on an already converted image without having to do the above.

[smthopr]

So, "preserve RGB numbers" is a way to soft proof an image that has already been converted to the printer profile space?  In other words, it converts the image back to your display space so that it can again be viewed as "normal"?

[Mark D Segal]

It does what I said it does in Reply #20.

[smthopr]

So, "preserve RGB numbers" is a way to soft proof an image that has already been converted to the printer profile space?  In other words, it converts the image back to your display space so that it can again be viewed as "normal"?

Actually, if I convert my image to the printer profile space, and select "preserve RGB numbers"  there is no change in the preview.  And, photoshop automatically converts the image to my display profile anyways when soft proofing is off.

Therefore, I can't see how this setting would help me, or the original poster, for softproofing at all.  Other than some technical issue, that I don't have, this setting doesn't generally apply to printing at home or sending a file to a commercial printer.  I can see using it only if I wanted to experiment with performing the color space conversion to printer space by eye, instead of using the printer profile conversion process.  An interesting idea, but not for normal printing...

[Mark D Segal]

Didn't say it was for printing at home; I would never use it for that either. I recall saying it's only used when preparing images for service bureaux where they provide the colour working space in which they want the images and their printer/paper profile, for softproofing.

[Mark D Segal]

Love the cinema on your website. Very cool stuff indeed.

[smthopr]

Didn't say it was for printing at home; I would never use it for that either. I recall saying it's only used when preparing images for service bureaux where they provide the colour working space in which they want the images and their printer/paper profile, for softproofing.

I understood that you were saying it's for when the printer provides a profile.  I just don't see it working for that at all either.  If you've converted your image to the printer profile, it will have no effect in the softproof as long as the image is tagged with the profile.  So, do you mean convert to the printer profile and then, in "assign profile", check "do not color manage" to remove the color space tag?  Yes, then this works.  I think the 2nd step of removing the tag wasn't clear to me in your post.

[smthopr]

Love the cinema on your website. Very cool stuff indeed.

Thank you so much Mark!!!!

[Doug Gray]

So, "preserve RGB numbers" is a way to soft proof an image that has already been converted to the printer profile space?  In other words, it converts the image back to your display space so that it can again be viewed as "normal"?

Yes, but only to display what the image would look like printed. As Andrew pointed out, it's rarely useful. And this has been even more true since Adobe, in their infinite wisdom, decided to disallow actually printing images in device space which requires disabling color management. There are workaround, but I digress.....

Most people just softproof the various options before printing or, more rarely, before converting to send out.

In fact the only things I can remotely think this is good for is: if you save a converted image you sent out for printing and forgot what conversion intent options you chose from the original. In that case you can use Preserve Color Numbers in soft proof and load the original in another window and run it through the Soft Proof conversion options to find out what you had once selected.

Here's another possibility. Say you are making a collage of images on a large size print and some you think look better using Perceptual while others look better using Relative. You can convert the images to the printer space then paste them on the large, blank collage which should have been pre-assigned to the printer's profile space. It might look off until you soft proof it with the Preserve Color Numbers.

It's all a very big stretch to come up with scenarios where the option is useful. That's all I can think of.

[Doug Gray]

Actually, if I convert my image to the printer profile space, and select "preserve RGB numbers"  there is no change in the preview.  And, photoshop automatically converts the image to my display profile anyways when soft proofing is off.

It is often the case but don't count on it. As I pointed out, how an image that has been converted to a printer profiles looks depends on the settings in the global "Color Settings" menu. For instance, if you happen to have those settings set to Rel. Col and BPC is not checked you won't see a change. OTOH, if you have BPC you will, especially if you are printing mattes.

[Tim Lookingbill]

Here's a demonstration of Soft Proofing to a Fuji Frontier Dry Lab inkjet printer that prints in the sRGB space: (meaning printer maintains similar saturation/hue/contrast of an image converted to sRGB given that it was edited on a calibrated/profiled display).

I downloaded from Dry Creek Photo's website a printer profile of the same model as the sRGB Fuji Frontier. Converted my ProPhotoRGB edited image to sRGB and assigned the Fuji printer profile TEMPORARILY FOR SOFT PROOFING (same as choosing Preserve RGB Numbers/PRGBN).

Below is the difference between the Fuji print and the actual source image and a picture of how it appeared on my display Soft Proofing through the printer profile in relation to sRGB space. Note the greenish yellows turned redder. That's about how off what you can expect Soft Proofing EXACTLY as described above.

If you convert to the printer profile Preserve RGB Numbers will not work because the image's RGB numbers are displaying through the printer profile in relation to your calibrated display.

[Doug Gray]

Actually, if I convert my image to the printer profile space, and select "preserve RGB numbers"  there is no change in the preview.  And, photoshop automatically converts the image to my display profile anyways when soft proofing is off.

Therefore, I can't see how this setting would help me, or the original poster, for softproofing at all.  Other than some technical issue, that I don't have, this setting doesn't generally apply to printing at home or sending a file to a commercial printer.  I can see using it only if I wanted to experiment with performing the color space conversion to printer space by eye, instead of using the printer profile conversion process.  An interesting idea, but not for normal printing...

I just checked this on the current version of CC. It's quite different than when I last had looked it and your observations are correct. It appears Adobe now uses the fact the image is in a printer's profile space to disable the various Intents in soft proofing. You can select Perceptual, Relative, Abs., Sat., BPC or not and NONE of them affect the softproof! Needless to say, selecting Preserve Color Numbers doesn't either though it does shift the now grayed out Intent to Relative. They all show exactly the same thing. Also, the settings in the global "Color Settings" dialog have no effect.

The only options that change the proof view are Show Paper Color and Blacks.

So in this incarnation of Photoshop Preserve Color Numbers does absolutely nothing because they bake it in.

But only if the image itself has the same printer profile. If, for instance, you select a different printer profile from the one the image has then it becomes unbaked! Suddenly, the various intents work.

So basically the Preserve Color Numbers does nothing normally. But there is one place where it is still necessary. If, after you convert the image to the printer profile and save it but not with the printer profile embedded. Then, when loaded in Photoshop unmanaged or arbitrarily assigned an RGB working space, Preserve Color Numbers will correctly produce a view proof.

[Mark D Segal]

Oh my goodness!! :-)

[Tim Lookingbill]

 The OP indicates he's printing at Costco that uses an inkjet printer that prints RGB data. So he needs to test the accuracy of the RGB profile Costco provided by printing two versions...one with the image converted to the profile and the second converted to sRGB (asking technician to set the printer driver to sRGB space if they can).

If both are off then Costco needs to get their printer maintenance to calibrate the printer. I asked that of Walmart photo dept tech and they soon called the technician under contract to do a maintenance/calibration routine and all was back to normal.

[Doug Gray]

The OP indicates he's printing at Costco that uses an inkjet printer that prints RGB data. So he needs to test the accuracy of the RGB profile Costco provided by printing two versions...one with the image converted to the profile and the second converted to sRGB (asking technician to set the printer driver to sRGB space if they can).

If both are off then Costco needs to get their printer maintenance to calibrate the printer. I asked that of Walmart photo dept tech and they soon called the technician under contract to do a maintenance/calibration routine and all was back to normal.

Good to know Walmart responded to your observation re the printer being off.

Note that DryCreek requires conversion to printer profiles in their database then submittal to Costco. If you, like the OP, are discussing DryCreek Costco profiles we probably should stick to their process.

[Tim Lookingbill]

Good to know Walmart responded to your observation re the printer being off.

Note that DryCreek requires conversion to printer profiles in their database then submittal to Costco. If you, like the OP, are discussing DryCreek Costco profiles we probably should stick to their process.

The OP made it clear that Costco's process is not working and that an alternative is to see if they can just print in the sRGB space. The DryCreekPhoto profile soft proofing outlined above is not suppose to give that close a match if the profile is using a process that's FAR AWAY FROM sRGB.

If 'A'-(Dry Creek Photo profile) is not equal to 'B'(unknown Costco processes) but 'B' is equal to 'C'-(Print match to image in sRGB) then what process or color space is the Costco printer using to build the profile? It must be very close to sRGB or else the prints should be WAY OFF.

And the Walmart Photo dept tech told me the printer needed maintenance. I just showed him the prints that had thin white parallel lines in large flat swaths of blue skies in some prints. Kinda' what shows in home printers needing print head alignment.

I was even surprised Walmart Photo dept manager would go to the extent of calling the maintenance tech for what I thought was my being too picky for such a minor flaw considering the 8x10 print cost $3.