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Author Topic: PDF/X-3 should have Black & Spot color, has CMYK and spot color  (Read 4747 times)

typomaxx

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Hi,

I've got the layout of a book ready: black text, greyscale illustrations and some dots, lines and parts of the text in a spot color. The printer requires a PDF/X-3 of the book. But my exported PDF has CMYK information in addition to black and the spot color. I don't know why.

I've defined the spot color as such. The illustrations have embedded "Dot Gain 15%" greyscale profiles. I've checked "use embedded profiles". I'm forced to choose an output profile; Scribus gives me only CMYK profiles to choose from - perhaps that's the reason for the unwanted behavior?

Any tips? It should be possible to make a PDF with Scribus that contains only two colors... but how?

Thanks!

utnik

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Re: PDF/X-3 should have Black & Spot color, has CMYK and spot color
« Reply #1 on: April 17, 2012, 12:03:09 am »
hi typomaxx

did you uncheck 'save as pdf' → 'color' → 'convert spot colors to process colors'? – this box is checked by default, but you need it unchecked.

utnik
« Last Edit: April 17, 2012, 12:16:17 am by utnik »

typomaxx

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Re: PDF/X-3 should have Black & Spot color, has CMYK and spot color
« Reply #2 on: April 17, 2012, 07:52:30 am »
Hi utnik,

yes, I've unchecked this box. I've got no problems with the spot color - the color separation for the spot color is correct. The CMY channels contain data of the illustrations - despite the fact that they have embedded greyscale profiles and - when analyzing the PDF - are reported as "greyscale". My guess is that the output profile of the PDF X-3 should be a greyscale profile - but Scribus don't offer me one (despite the fact that there's one installed).

max

utnik

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Re: PDF/X-3 should have Black & Spot color, has CMYK and spot color
« Reply #3 on: April 17, 2012, 08:59:50 am »
hi typomaxx

where are this illustrations from?
if you build them in scribus, you have to select the pure 'black' (0%,0%,0%,100%) – depending on your color set, there are many different shades of 'black'.
if the illustrations are generated in another application, you should check the colors before the import.
acording to the specifications of pdf/x-3, scribus doesn't convert the colors while generating the pdf…

utnik

edit: how are the grays in your illustrations buildt? (cmy, cmyk, k only, rgb…)
« Last Edit: April 17, 2012, 10:14:00 am by utnik »

mrdocs

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Re: PDF/X-3 should have Black & Spot color, has CMYK and spot color
« Reply #4 on: April 17, 2012, 10:26:01 pm »
Scribus does not support grey scale icc profiles. We did and it was problematic, as many gray scale profiles were garbage and caused crashes and other problems.


utnik

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Re: PDF/X-3 should have Black & Spot color, has CMYK and spot color
« Reply #5 on: April 17, 2012, 10:36:40 pm »
Scribus does not support grey scale icc profiles.

as long as all the shades of gray are generated by the 'K' channel only, the imported picture may be a cmyk file – all other channel are empty…

utnik

typomaxx

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Re: PDF/X-3 should have Black & Spot color, has CMYK and spot color
« Reply #6 on: April 19, 2012, 08:46:32 am »
Hi, I've done these illustrations in GIMP and saved them there as greyscale. When generating a PDF/X-3 Scribus forces me to attach a color profile to the illustrations (or to use the embedded one). I don't know why Scribus does this; the PDF/X-3 standard doesn't require an illustration to have a color profile. The result is that the GIMP illustrations (without color profile embedded) become RGB illustrations in the PDF/X-3. To avoid this I asked a friend to save the illustrations in Photoshop with "Dot Gain 15%"-profiles embedded into them. Scribus accepts these embedded profiles; nevertheless there's information in the CMY channels when exporting a PDF/X-3.

My "solution" so far was to generate a PDF 1.3 of the book with the GIMP illustrations and color management disabled. This PDF has at least no data in the CMY channels. Let's hope that the printer is able to work with it...

Thanks for your help! (And give me a hint if you know why I can't generate a PDF/X-3 with Scribus without using color profiles for images...)
« Last Edit: April 19, 2012, 08:48:19 am by typomaxx »

utnik

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Re: PDF/X-3 should have Black & Spot color, has CMYK and spot color
« Reply #7 on: April 19, 2012, 09:48:57 am »
hi typomaxx

…Scribus forces me to attach a color profile to the illustrations (or to use the embedded one). I don't know why Scribus does this; the PDF/X-3 standard doesn't require an illustration to have a color profile.

that's exactly what the pdf/x-3 standard requires: all images must have an embedded color profile – this is mandatory!

if yo have a correct grayscale profile in gimp, use this. otherwise you need the 'separate' plugin to export your grayscale picture in cmyk (hapefully with empty cmy channels…)

another possible solution (not tested by be, but looks elegant…):
  • build your layout with text, images and spot color objects
  • select the imported picture
  • add: 'properties' → 'images' → 'image effects' → 'grayscale'
  • go to: 'edit' → 'colors' and klick 'remove unused'
now you should have 100% black and your spot color remaining.

i'm not sure, if this works – but with your project, i would try it and check with my printer (and post the result here…)

utnik

Nermander

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Re: PDF/X-3 should have Black & Spot color, has CMYK and spot color
« Reply #8 on: April 19, 2012, 11:24:25 am »
Are you 100% sure that the images you save in GIMP are really saved as real grayscale? To achieve that you will have to use Image -> Mode -> Convert to color profile.

Otherwise I think "grayscale" images will still be saved as RGB images.


I'd suggest using for example ImageMagick to do the conversion to make sure it is really grayscale.

typomaxx

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Re: PDF/X-3 should have Black & Spot color, has CMYK and spot color
« Reply #9 on: April 21, 2012, 12:46:34 am »
Hi utnik,

that's exactly what the pdf/x-3 standard requires: all images must have an embedded color profile – this is mandatory!

I've also thought this but I'm not sure any longer that this is true. The german "Bundesverband Druck und Medien" writes in his statement about PDF/X-3 specifications that I've read some days ago (in this PDF on page 16 if you're able to read german: http://www.bvdm-online.de/Aktuelles/Downloads.php?Action=GetFreeFile&FileID=19 ): "By the way: it's in no way mandatory that you have to use ICC profiles for pictures or other objects in PDF/X-3 files - in fact it's completely permitted to build a PDF/X-3 with CMYK and spot colors." It's possible that I don't understand the true meaning of this sentence but to me it seems that the use of color profiles for images in PDF/X-3 files is not mandatory.

Concerning the idea of using the Scribus effect "greyscale": I've already tried this but only with the first two illustrations to test it - without success. Since you've got the same idea I've added this effect to all images (thinking that perhaps unwanted colors remained because I didn't use the "greyscale" effect on all illustrations), used "remove unused colors" and generated a PDF/X-3 with "ISO Uncoated Yellowish" as output profile: There's still color information in the CMY channels of the illustrations. Don't ask me why! (But thanks for your idea.)

@nemander: I didn't know that, thanks for the hint. I'm out of office for a week starting tomorrow; I'll try it when I'm back. But I'm not sure that it will help: The illustrations I've used to generate the PDF/X-3 are converted to greyscale in Photoshop (with attached "Dot Gain 15%" profile). For the PDF 1.3 that I've generated as an alternative with deacticated color management I've used the GIMP illustrations - and there's no color information in the CMY channels so it works as desired already.

By the way: Yesterday the printer told us that they've succeeded in converting the PDF so that it contains only two colors and everything's ok now. Today they've told us that their "program" (?) (perhaps the software of their printing machine?) won't open the PDF file but that there's no error message so that they don't know why (and we have no hint how to "fix" our seemingly unbroken PDF file so that it works). Still very exciting ...

Nermander

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Re: PDF/X-3 should have Black & Spot color, has CMYK and spot color
« Reply #10 on: April 21, 2012, 02:17:28 pm »
When googling about the issue I found posts indicating that Photoshop 7 had a bug where grayscale images were saved as RGB. So if they were made with Photoshop 7 that might be the issue.


 

palmate