Book Printing

Hopefully a new question on ICC Profiles! Blurb's sRGB vs HP5000 CMYK...

Hi,

I know a lot of questions have been posted about colour management already but hopefully this is new information, a quick search didn’t show anything up. Here we go:

So the method most commonly used / endorsed is to edit your photos in sRGB IEC61966-2.1, and then proof them against the HP5000’s ICC profile, bringing the proof-ed image back to look identical to the original under the sRGB profile before sending it for printing.

But… Blurb actually give out their own sRGB ICC profile, available here:

http://blog.blurb.com/index.php/2007/02/13/color-profile-for-blurb-books/

So shouldn’t we be using that to either edit in instead of the sRGB IEC61966-2.1, or shouldn’t we be using that to proof against, i.e. sRGB IEC61966-2.1 against Blurb’s sRGB?

The differences between the normal sRGB and Blurb’s sRGB are quite significant, on my screen at least, generally having less saturation and contrast.

Also, the Blurb ICC profile is from Feb 2007, so are they still using the same one given all the discussion that’s gone on over the years? Anyone from Blurb able to comment?

Thanks!

Replytopic_b_normal
Posted by
prglewis
Mar 17, 2010 1:23pm PDT
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prglewis
 

Sorry my link above is wrong, it should be:

http://www.blurb.com/guides/pdf_to_book/intro

Look towards the bottom of the page under “A Brief Note on Colour”, point 2.

The direct download link is:
http://blurb.com/downloads/Blurb_ICC_Profile.icc.

And I didn’t spot a date on there, not sure if its from Feb 2007 or later…

Posted by
prglewis
Mar 17, 2010 1:48pm PDT
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prglewis
 

Hi,

The download link you reference directly above – http://blurb.com/downloads/Blurb_ICC_Profile.icc – is current and the correct one to use. 

Thanks!

– Kathy

Posted by
kathybad
Mar 17, 2010 5:26pm PDT
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kathybad
 

Thanks Kathy.

I have a question on the rendering intent as well. People seems to be using “Perceptual” as the rendering intent but I’ve been thinking about this…

Perceptual:
- Colour values are changed to keep the relationship between in gamut and out of gamut colours visually the same, so both in gamut and out of gamut colours are changed
- Suggests this is the standard for the Japanese printing industry

Relative Colourimetric:
- In gamut colours kept the same
- Out of gamut colours shifted to the nearest in gamut colour
- Suggests this is the standard for the North American and European printing industries

So shouldn’t we use Relative Colourimetric instead of Perceptual as this will preserve more of the original image colours?

All depends on how Blurb converts the colours from sRGB to CMYK I guess, do we have methodology info on that?

Cheers!

Posted by
prglewis
Mar 18, 2010 6:11am PDT
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prglewis
 

Good question. We actually have more color management help on the way to the site very very soon. In the meantime, go ahead and select "Perceptual" as the Intent and "Adobe ACE" as the Engine to achieve the best possible match between Adobe RGB and sRGB without losing subtle gradations and transitions.

Hope this helps.

– Kathy

Posted by
kathybad
Mar 18, 2010 8:56am PDT
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kathybad
 

Thanks Kathy, but I think you’re referring to converting between colour spaces through the Edit/Convert to Profile option. I’m still referring to proofing.

My image is in sRGB and I’m proofing in the Blurb ICC Profile and looking at the options under the View/Proof Setup/Custom menu, there’s no option for engine choice. So is it still the same, use Perceptual to proof?

Do the Blurb software or the printers use Perceptual as the conversion method when they’re converting from sRGB to CMYK for printing?

Thanks again.

Posted by
prglewis
Mar 18, 2010 9:11am PDT
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prglewis
 

OK, take two …

If you are Proofing your sRGB images within Photoshop, set your Proofing Condition to the Blurb ICC Profile as your Device to Simulate and set the Rendering Intent to Perceptual, leaving Black Point Compensation and Simulate Black Ink selected. Also, leave Paper Color unselected.

Our print network does use Perceptual Rendering when making the conversion from sRGB to CMYK for our print devices. This rendering intent gives the most pleasing results with the majority of photography as it maintains gradations and subtle shading much more effectively than Relative Rendering. Please note though, that ONLY colors outside of the CMYK color gamut are changed (rendered) when making this conversion.

And that should do it. For information beyond that, I encourage you to work with others in the forum or look to third-party resources. 

– Kathy

Posted by
kathybad
Mar 18, 2010 12:56pm PDT
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kathybad
 

Hi, Kathy

I just received the first copy of my book, Sotto Voce, which shows – among other production problems - a very dominant magenta cast.  I downloaded the new Blurb_ICC_Profile.icc but when I try to soft proof it in Photoshop it says cannot open because it is not available with this version of Photoshop!  I am using Photoshop CS3 for goodness sakes.  Can you tell me how to access it so my next book will not have this problem?  Many thanks. Robynne

Posted by
RLimoges
Mar 30, 2010 5:10am PDT
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RLimoges
 

Hi,

That does sound a bit strange. Have you watched our install video to make sure you followed the correct steps? If so, and still no luck, please contact Customer Support directly so they can diagnose the issue.

– Kathy

Posted by
kathybad
Mar 30, 2010 9:33am PDT
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kathybad