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mattzory
Known Participant
February 20, 2017
Answered

True B&W for Blurb Books

  • February 20, 2017
  • 2 replies
  • 3528 views

Hi All,

I've done one book several times thru the Blurb Book export module. The B&W is always tinted magenta. I do the conversion in LR. Here's the issue I believe: it goes to Blurb as sRGB. I've recently done the same book locally and the printer needed to convert all the BW's to grayscale in PS To get an untoned BW. Anyway around this using the LR to Blurb export module. I hope I've made this clear! Thanks.

Matt

This topic has been closed for replies.
Correct answer Per Berntsen

I think you may have a hard time getting neutral  B&W from Blurb. They apparently use the same CMYK icc profile for every type of paper, and the profile should be optimized for the ink/paper combination. One size doesn't fit all here.

How to get neutral results when printing B&W images in CMYK has puzzled me for years, but through a book I am about to print  soon with an extremely knowledgeable printer, I have learned a little about it.

First of all, the printing equipment has to be well calibrated. That includes the press itself, and the CTP (Computer To Plate) imagesetter. My printer calibrates the CTP weekly.

With proper calibration, using the correct profile, and a press operator who knows his job, you should now get neutral results when viewed by daylight (or the 5000 K light next to the printing press). When viewed in artificial light, there will be a magenta cast, which is caused by the way the ink absorbs and reflects colors when a different light source is used.

This color shift can be reduced (but not completely eliminated) by using a custom CMYK setup in Photoshop.

(There is no way to do this with Lightroom, since it only works in RGB.)

Open the CMYK file in Photoshop, then go to Edit > Convert to profile, and choose Custom CMYK, which will open this dialog.

By default, the GCR (Gray component replacement)  is set to Medium.

Changing the GCR to Heavy, uses less CMY and more black ink, as you can see from the curves.

With less colored ink, the magenta cast will be reduced when viewing in artificial light.

Please note that the other settings in this dialog are just default settings. Using this workflow would require that you work closely with the printer, who should be able to tell you what settings to use. I guess not all printers would be willing to, or have the required knowledge to do this. And you should of course do a test run first, and also be present when the real job is done.

Using grayscale images is also an option, but the tonal scale will be reduced a great deal compared to CMYK.

Another option is to print in  duotone, tritone, or even quadtone, (black plus one, two or three gray inks), but this is specialist work, and may be quite expensive.

2 replies

F. McLion
Community Expert
F. McLionCommunity Expert
Community Expert
February 21, 2017

Interesting discussion

I just went through some sort of a nightmare including long discussions with the technical boss of the print shop while trying to get acceptable B/W print on mid-sized canvas (0.6 by 0.6 m). At the end, they simply could not do it. All they have tried, the prints always had a color cast. They also were unable to give me a profile of their printer to be able to check/work with it. We agreed for a full refund.

I know this from various fine art paper I use and where it is impossible to print to without having the printer calibrated with every paper (separate color profile for every paper, generated with SpyderPrint).

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Per Berntsen
Community Expert
Per BerntsenCommunity Expert
Community Expert
February 21, 2017

F. McLion wrote:

They also were unable to give me a profile of their printer to be able to check/work with it.

That should raise a red flag, and the best thing to do would be to find a different printer who can tell you what profile to use.

I also had a nightmare experience many years ago, with images having all sorts of casts throughout the book - magenta, cyan and yellow. Some of them even had different casts in shadows and highlights.

Just remembered the name of the problem - when you see a color cast using a different light source - metamerism.

As pointed out by John Beardsworth, this is much less of a problem with modern inkjet prints - prints from my Epson 9880 change very little when viewed with different light sources. I use the Advanced black & white setting, which uses small amounts of colored ink in addition to the black and gray inks.

M
mattzoryAuthor
Known Participant
February 21, 2017

With my Epson I also use the Advanced B&W---works great. I also use a local lab for bigger things and they don't provide ICC's but they do provide awesome service. We know each other and I only see high quality work from them. If it's tricky I bring them a small print as a reference. The only thing they can't get neutral are metal prints. And Per, I had your exact issue when I first tried to reprint my Blurb book locally. The tech person there loved the problem by converting all the B&W files to grayscale in PS. I'd provided them as sRGB jpg.

john beardsworth
Community Expert
john beardsworthCommunity Expert
Community Expert
February 20, 2017

You're struggling with colour inks being used to produce B&W, so Blurb's printers and yours will mix and balance a number of colour inks and try to produce neutral output. While things are better than in the past, they're just not going to be perfectly-neutral. I've printed a lot of books through Blurb, including plenty of B&W content though none that were only-B&W, as far as I recall. If the colour cast is really bad, my suggestion would be to contact Blurb's support and see if they will reprint it with a human checking the B&W neutrality and maybe switching off some "auto" button.

M
mattzoryAuthor
Known Participant
February 20, 2017

Hi John,

Blurb suggested I do tests---send my images tinted one way or the other to counter the shift that occurs when they print. What would work best---I think---is if the B&W's could be sent converted to grayscale as my local print company did for me in PS. I have PS and could do that but it's so cool to have those templates that are built into LR already. The magenta shift that occurs isn't readily noticeable in all lighting situations and most of my customers wouldn't notice it---but I do! BTW, they agreed with me when I first brought it up and reprinted my whole order at no charge---but then I had twice as many with the magenta tint! (they did sell however...)

john beardsworth
Community Expert
john beardsworthCommunity Expert
Community Expert
February 20, 2017

Yes, I know the feeling - you have to be happy yourself. I've never been as content with B&W neutrality as I was when I used pure BW inks in my inkjet printer. 10 years ago there used to be a few different vendors, but today's printers produce much more neutral results and the market seems to have gone. I think Piezography​ is the only vendor around (could be wrong) if you can afford a dedicated printer.

I do have a theory that my mixed colour-B&W content is easier for Blurb's software. But it may just be that colour pages make your eyes less sensitive to any magenta shifts that may be there....

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