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Author Topic: Greyscale images become RGB in Scribus  (Read 3167 times)

typomaxx

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Greyscale images become RGB in Scribus
« on: April 04, 2012, 09:42:23 pm »
Hi,

I'm doing a book in Scribus. The final product should be a PDF X/3 with two colors: black and one spot color. The book contains illustrations saved as greyscale PNG in GIMP. When I place them within picture frames in Scribus a RGB profile is assigned to them; this is a problem for our printer.

I've found no way to tell Scribus to handle the illustrations as greyscale. I've searched the web, the documentation and this forum; I've found some people with a similar problem but no solution (at least none I was able to understand ;) ). At http://wiki.scribus.net/canvas/1.4.0_Release_Supplemental_Notes they mention a closed bug "9829: [PDF] [FIX] patch for always exporting greyscale images as greyscale in PDF (jghali) - closed." This seems to imply that it should be possible to tell Scribus to import and export illustrations as greyscale.

Any help is much appreciated. Thanks!
« Last Edit: April 05, 2012, 09:25:56 am by typomaxx »

Wena

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Re: Greyscale images become RGB in Scribus
« Reply #1 on: April 04, 2012, 11:40:13 pm »
typomaxx, to produce Grayscale i usually use "desaturate"  under the pull down colour menu in Gimp.

You mention a 'spot colour'  is it inside the book, just one colour?

You also mention above that it is in RGB, you must have elected for it to be so! Gimp normally export in CMYK. Is it that the printer needs it to be in RGB?

Has the printer given you instructions to produce RGB?

Are you using Gimp 1.4?

Wena

typomaxx

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Re: Greyscale images become RGB in Scribus
« Reply #2 on: April 05, 2012, 09:09:16 am »
Hi Wena,

sorry for the confusion. I'll try to clarify:

- I use the latest stable version of GIMP (it's 2.6.12 I think). There I save the PNG as grayscale image. No problem about that - the PNG on my hard drive contains only black and its color mode is grayscale.

- My printer needs it to be in grayscale mode.

- When I import the PNG into an image frame in Scribus and checking its properties Scribus has a RGB profile attached to it. This is the problem. I don't know how to convince Scribus to handle it as grayscale image. (I've activated color management within Scribus; I think I need it because of the spot color appearing elsewhere in the book and because of the PDF X/3 format - but I'm not shure about that; it's possible that there's the reason for the unwanted behavior.)

Nermander

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Re: Greyscale images become RGB in Scribus
« Reply #3 on: April 05, 2012, 09:15:45 am »
When exporting a PDF in Scribus you have three choices:

Screen/web - gives RGB PDF
Printer - gives CMYK PDF
Grayscale - have a guess

The problem here is that since PDF/X-3 allows images do be included "as is" I am not sure if any conversion will be done when exporting to PDF/X-3. The whole point with X-3 is to leave the conversion to the printer.

typomaxx

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Re: Greyscale images become RGB in Scribus
« Reply #4 on: April 05, 2012, 09:37:00 am »
Hi Nemander,

thanks for your answer. I use the "printer" export option - I don't think that I can use "grayscale" because of the spot color.

I think the problem is related to the X-3 format. When choosing X-3 the option "use color profile" at the "color" tab of the PDF export option dialog is marked - and it's not possible to unmark it. I'm not sure but I think that's the reason the grayscale image becomes a RGB image. With other PDF formats it's possible to unmark this option (and to deactivate color management completely), but our printer wants X-3.

Perhaps I should try to find a grayscale ICC profile and assign it to the images?

Nermander

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Re: Greyscale images become RGB in Scribus
« Reply #5 on: April 05, 2012, 09:52:40 am »
Yes, using a grayscale profile sounds like a possible solution.

I think the "use color profile" you are referring to is what profil to use for images not containing a profile, and that is because since PDF/X-3 allows embedding the images without conversion every image must have a profile. So the profile selected there will be used for all images not having a specific profile.

typomaxx

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Re: Greyscale images become RGB in Scribus
« Reply #6 on: April 05, 2012, 10:03:14 am »
Well, I've just tried to assign a grayscale profile within Scribus to the images but it's not possible - I've installed grayscale ICC profiles but within Scribus I can only choose between RGB profiles; the grayscale profiles are not offered as an option.

Ok, I'll try to embed a grayscale profile into the image within GIMP. Stay tuned ;-) (No, don't do it, this will take some time...)

Thanks for your help so far!

Nermander

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Re: Greyscale images become RGB in Scribus
« Reply #7 on: April 05, 2012, 11:00:25 am »
I have since long given up to try to learn color management, but I think the profile for a grayscale image is different than the profile for a grayscale printer. So make sure the profile you have is really intended for images.


typomaxx

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Re: Greyscale images become RGB in Scribus
« Reply #8 on: April 06, 2012, 09:27:54 am »
Hi,

embedding a "Dot Gain"-profile into the image with Photoshop worked! A friend of mine tried it for me - I had no such profile to try it with GIMP myself. Now Scribus associates the image no longer with a RGB profile but shows "Embedded Dot Gain" instead. Great!

Thanks for your help!

 

palmate