CM Policies: Preserve Embedded Profile or Convert to Workspace?

[dwanehollands]

Hi All,

Just wondering what peoples recommendations for Colour Management Policies in Photoshop. Do you set it to Preserve Embedded Profiles or Convert to Working RGB/CMYK/Gray?

Our policy has always been to convert to Working CMYK/RGB/Gray when we import images from other sources.

1. If the profile is embedded with the image will photoshop do a simple profile-to-profile conversion?
2. Does an image with "no profile" simply inheret the CMYK Working space profile,or does it attempt to do a conversion - what source colour space does it assume for the conversion?

What does your shop do?

regards,

Dwane

 

[Lukas Engqvist]

Re: CM Policies: Preserve Embedded Profile or Convert to Workspace?

In Photoshop, Colour Management is usually keep the profile if it has a profile, but let me expand.

RGB images
If there is a profile embeded and the image is ok… don't touch.
If it is a screen dump, I would tag sRGB and then convert to CMYK with maximum GCR after which i untagg. (the reason being I want to break the CMM cycle)
Untagged images, view with different ICC, usually can tell consumer picts or screen would be sRGB, Photoshoots are likeley to be AdobeRGB other profiles are usually included (also try colourmatch for print reruns). When it seemsI've found it, tagg the image.
We work with ECI RGB, so if I do any editing or the picture contains bright yellows I will convert to ECI RGB before editing.

CMYK images
Often CMYK images are tougher, In most cases convert to RGB so that they can be colur managed, often a shadow highlight can bring our lost information n shadows.

NOTE smartobjects
On a cover or if unsure of the purpose if you convert the RGB image before changing to CMYK you get the best of both worlds you can have adjustment layers in RGB and CMYK depending on if it is inside or outside of smart object.
So the Image can have adjustments in Hue saturation and shadow highlights (smart object within smartobject) in RGB, and then apply a sharpening in the CMYK shell on the RGB smart object. This bloats file size but is the ultimate non-destructive multipurpose image.

INDESIGN
When opening in InDesign I choose RGB enable all profiles, since sources can be mixed. CMYK dissable all profiles to honour values (this is why CMYK files with the wrong ICC need to be converted to RGB).

In The PDF I use the output intent to tagg the file for the CMYK to giva a clear label, embedding CMYK can give unwanted CMYK to CMYK between comatible CMYK profiles (ISO Coated v2, FORGA 27, FOGRA 39 & our own profile with higher GCR than standard profile etc)

 

[dwanehollands]

Re: CM Policies: Preserve Embedded Profile or Convert to Workspace?

Luke,

Thank you so much for such a comprehensive response!

I'm slowly digesting everything...

> (the reason being I want to break the CMM cycle)

What do you mean by breaking the CMM cycle? What is the problem with it? Something to do with the RGB>LAB>CMYK conversions?

> Untagged images, view with different ICC, usually can tell consumer picts or screen would be sRGB, Photoshoots are likeley to be AdobeRGB other profiles are usually included (also try colourmatch for print reruns). When it seems I've found it, tagg the image.

Ok, excellent TIP!

> We work with ECI RGB, so if I do any editing or the picture contains bright yellows I will convert to ECI RGB before editing.

Excellent TIP! I've heard that ECI (European?) RGB had better yellows.

> CMYK images
> Often CMYK images are tougher, In most cases convert to RGB so that they can be colur managed, often a shadow highlight can bring our lost information n shadows.

Another fantastic tip!

> NOTE smartobjects
> On a cover or if unsure of the purpose if you convert the RGB image before changing to CMYK

Do you mean convert to a particular RGB profile which is best performing for that particular smart object?

>you get the best of both worlds you can have adjustment layers in RGB and CMYK depending on if it is inside or outside of smart object. So the Image can have adjustments in Hue saturation and shadow highlights (smart object within smartobject) in RGB, and then apply a sharpening in the CMYK shell on the RGB smart object. This bloats file size but is the ultimate non-destructive multipurpose image.

Very interesting. Never had much to do with Adjustment layers.

> INDESIGN
> When opening in InDesign I choose RGB enable all profiles, since sources can be mixed. CMYK dissable all profiles to honour values (this is why CMYK files with the wrong ICC need to be converted to RGB).

Ahh, ok. And let Indesign do the conversion on those images? Safe or good conversion? Just use the Proof Setup as Working CMYK to ensure it will convert ok? (with proof colours on - toggle Gamut Warning on/off?)

> In The PDF I use the output intent to tagg the file for the CMYK to giva a clear label, embedding CMYK can give unwanted CMYK to CMYK between comatible CMYK profiles (ISO Coated v2, FORGA 27, FOGRA 39 & our own profile with higher GCR than standard profile etc)

OK, I'm a little confused by what you mean here. Is there a difference between tagging and embedding? I'm guessing the issue you're talking about is when the purity of C, M, Y, CM, CY, MY are 'contaminated' for sake of accuracy?

Thanks again Luke!

 

[madflexo]

Re: CM Policies: Preserve Embedded Profile or Convert to Workspace?

Anyone know of some websites that breaks down color management in photoshop? I'd like to learn more about how profiles and working spaces interact with photoshop. When to tag an image and when to discard all profiles.

Thanks
Steve

 

[Lukas Engqvist]

Re: CM Policies: Preserve Embedded Profile or Convert to Workspace?

haven't figure out how to do quotes yet ;P

I'll answer back to front.
Yes there is a difference between tagging a PDF as "output intent" and embedding. Tagging means the ICC tagg is outside the data, and it is still device CMYK. The reason I would suggest this is that device cmyck is untouched by colour managing.
If you tagg all CMYK you may end up getting richer blacks and contaminated yellows etc. And ICC profile is built on data, but there can be several ICC profiles ( eg with different GCR settings) from the same measuring data.
An example: there is an ISO coated with ink limit 300% ink and another with 350% ink, you would not want to convert colours between these profiles as they should be identical, but many colourmanagement engines will convert if you have embedded with the one and print with the other. The output intent is however a hint for me (as service provider) to know if the PDF file was created for a coated or uncoated paper, and so I want the label.

Yes, we do convert colours in InDesign, it has the same colour engine as Photoshop. So pictures are proofed and printability confirmed useing gamut warning to determine risk areas (note that gamut warning is just to make you aware of colours that are too intense, the soft proofing shows how colurs will be affected. We use relative conversion for coated papers and perceptual for uncoated as standard… but have found some images actually give better results using relative even on uncoated)

Adjustment layers are non destructive ways to compensate for out of gamut colurs. As they are selective I prefer using HSB to homegonise reds towards yellow yellows towards red very small increments (helps skin tones). Blues often need to go towards cyan and reduce saturation, reds towards magenta and darken. The nice thing with an adjustment layer besides being non destructive is that it can be copied from one image to the next, and it can also be used with a layer mask to limit the area it is applied. As a bonus if you save the file as a PSD you can enable or dissable the layer in InDesign.

Smart objects are also non destructive ways of editing.
If you have an RGB image and conver all the layers to a smart object then changing colour mode is a live effect.
(You just have to try it. I can't explain it here, and it would probably be a better tutorial or alternate post.)

I will try to show with simple formatting:

Indesign (colour managed)
PSD file (CMYK mode, ICC according to output)
Sharpening applied (optional layer mask for areas that don't need sharpening)
Channel mixer or Levels (to remove impurities in yellow)
Smart object (doubble click to open RGB file)
RGB (Tagged with ICC profile)
Smart object (applied shadow highlight for better detail in shadows)
Adjustment layer HSB (with optional layer mask) – for out of gamut colours and/or skintones
can be applied in blend mode colour
Adjustment layer Curves (with optioal layer mask) – for global adjustment
Original image untouched
/smart object
/smart object
/PSD
/indesign

since it is bloated file size this would be an exception, normally I would leave it at:

Indesign (colour managed)
PSD file (RGB mode, ECI ICC) - viewed in Photoshop using gamut warning and proof colours
Levels (to clip 2% to white)
Smart object (Shadow highlight & Sharpening applied )
Adjustment layer HSB (with optional layer mask) – for out of gamut colours and/or skintones
can be applied in blend mode colour
Adjustment layer Curves (with optioal layer mask) – for global adjustment
Original image untouched
/smart object
/PSD
/indesign

I find that using different RGB profiles is less of a problem than having no profiles.

 

[Lukas Engqvist]

Disgarding profiles

Disgarding profiles

There are only two instances you want to disgard a profile.
1) if you are exporting to web and have converte to sRGB (to get the file size down)
2) You are more interested in preserving the values than the appearance of a CMYK file. (a colured technical drawing where intensity/purity is more important than exact colur)

Adobe has a white paper on colormanagement http://www.adobe.com/studio/print/pdfs/CS3_color_workflows.pdf

 

[dwanehollands]

Re: Disgarding profiles

Re: Disgarding profiles

Again Excellent information. I understand why you want to switch off the tagging now. Keep the colors pure etc.

>FYI, to get the quoting working there are quote marks on the toolbar in 'plain Text' edit mode. If you click that on it will paste the info from the post that you replied to. In fact you only need to put a SHIFT-PERIOD at the start of a paragraph to get it to be boxed like that. Such as this one, had a single SHIFT-PERIOD at the beginning of it.

I've attached a picture of what I normally see in my browser.

Edited by: Dwane Hollands on Jul 31, 2008 10:08 PM

 

[Lukas Engqvist]

Re: Disgarding profiles

Re: Disgarding profiles

> {quote:title=dwanehollands wrote:}{quote}
> >FYI, to get the quoting working there are quote marks on the toolbar in 'plain Text' edit mode. If you click that on it will paste the info from the post that you replied to. In fact you only need to put a SHIFT-PERIOD at the start of a paragraph to get it to be boxed like that. Such as this one, had a single SHIFT-PERIOD at the beginning of it.
OK! cool, now you will be quoted ;P

And glad to be of help… would be interesting to hear if there are more ideas. Confirmation or confrontation as long as it's informative

 

[leonardr]

Re: CM Policies: Preserve Embedded Profile or Convert to Workspace?

> {quote:title=Lukas Engqvit wrote:}{quote}
> Yes there is a difference between tagging a PDF as "output intent" and embedding. Tagging means the ICC tagg is outside the data, and it is still device CMYK. The reason I would suggest this is that device cmyck is untouched by colour managing.
> The output intent is however a hint for me (as service provider) to know if the PDF file was created for a coated or uncoated paper, and so I want the label.
>

There is both good information and bad in the above comments, and I'd like to clarify the situation.

PDF 1.3 added the concept of an "Output Intent" (OI) to the PDF language at the request of the ISO 15930 (PDF/X) committee. The OI can either be an embedded ICC profile or the name of a profile at a "standard location" (eg. http://www.color.org). An OI in a standard PDF document can/will be ignored by a viewer (such as Acrobat).

HOWEVER, in a PDF/X file (X-1a, X-3, X-4, etc.) the conforming viewer is REQUIRED to use that profile as the source profile for all untagged content (images, vector, and text) in the matching color space. So that means that when you view a PDF/X file in Acrobat/Reader, it is using the embedded profile for source profile and NOT whatever working space you have defined. In addition, Acrobat/Reader will use that profile at print time as well. So color managed is ALWAYS involved and the OI is NEVER a "hint".

Hope this helps.

Leonard

 

[Lukas Engqvist]

Re: CM Policies: Preserve Embedded Profile or Convert to Workspace?

> {quote:title=leonardr wrote:}{quote}
> HOWEVER, in a PDF/X file (X-1a, X-3, X-4, etc.) the conforming viewer is REQUIRED to use that profile as the source profile for all untagged content (images, vector, and text) in the matching color space. So that means that when you view a PDF/X file in Acrobat/Reader, it is using the embedded profile for source profile and NOT whatever working space you have defined. In addition, Acrobat/Reader will use that profile at print time as well. So color managed is ALWAYS involved and the OI is NEVER a "hint".

Yes the point is that the customer will view the PDF with the correct output intent, this is necessary for the customer to have realistic expectations.

However it is not true that colour is allways managed. That depends on if the RIP is set to honour OI, ofcourse I don't usually print from Acrobat but drop the PDF on the RIP. But have not seen any effects on the PDF or output other than that Acrobat defaults to screen proof Output Intent.

We have been using this for a long time (PDF/X1 and PDF/X4) so I know that is a fact (there is the option in the PDF Print Engine to honour the Output Intet but it is not compulsory).
Embedding the profile forces Colour Management however, and taggs objects in the PDF as ColourManaged CMYK.
If you have different information I would like to know what the source for that information is, and under what circumstances, because I can't reproduce it.

 

[Lukas Engqvist]

Ignoring output intent

Ignoring output intent

> {quote:title=leonardr wrote:}{quote}
>An OI in a standard PDF document can/will be ignored by a viewer (such as Acrobat).
> In addition, Acrobat/Reader will use that profile at print time as well. So color managed is ALWAYS involved and the OI is NEVER a "hint".

In the print dialogue in Acrobat it is possible under the advanced menu to choose "Same as source (No Color Management)"

 

[leonardr]

Re: CM Policies: Preserve Embedded Profile or Convert to Workspace?

> {quote:title=Lukas Engqvit wrote:}{quote}
> However it is not true that colour is allways managed. That depends on if the RIP is set to honour OI,

If you do that, you are now outputting your documents in violation of the PDF/X standard.


>ofcourse I don't usually print from Acrobat but drop the PDF on the RIP. But have not seen any effects on the PDF or output other than that Acrobat defaults to screen proof Output Intent.
>

It's more significant with PDF/X-4 and live transparency.


> Embedding the profile forces Colour Management however, and taggs objects in the PDF as ColourManaged CMYK.
>
Correct. In fact, that's one reason why PDF/X-4 doesn't allow embedded profiles that match the OI profile.


Leonard

 

[leonardr]

Re: Ignoring output intent

Re: Ignoring output intent

> {quote:title=Lukas Engqvit wrote:}{quote}
> > In addition, Acrobat/Reader will use that profile at print time as well. So color managed is ALWAYS involved and the OI is NEVER a "hint".
> In the print dialogue in Acrobat it is possible under the advanced menu to choose "Same as source (No Color Management)"
>
True, but that's NOT the default - especially for PDF/X-compliant documents.

Leonard

 

[Lukas Engqvist]

Re: CM Policies: Preserve Embedded Profile or Convert to Workspace?

> {quote:title=leonardr wrote:}{quote}
> > {quote:title=Lukas Engqvit wrote:}{quote}
> > However it is not true that colour is allways managed. That depends on if the RIP is set to honour OI,
>
> If you do that, you are now outputting your documents in violation of the PDF/X standard.

Hmm… violation, sounds bad …but seriously that to me sounds as a weakness, since you would get different ICC profiles for different GCR values though the ICC profiles are from the same measurement data. This is especially a problem as Adobe setts "FOGRA 27" as the europe prepress default. I would never want to do a CMYK - CMYK conversion between FOGRA 27, FOGRA 39, ISO Coated v2, ISO Coated v2 300% (ECI).

It would be a violation if the profiles were from different measurement data. But since they are from the same data and ICC profile and not the source data is the basis to determine if CMYK - CMYK conversion should happen I would think that a "compatibility list" ought to be added to rips, (and be allowed without calling it violation of standard) in much the same way as fonts are compatible if style is normal & regular.

I guess the old saying to break the rules is OK as long as you do "wrong" the "right" way.