Author Topic: Ink coverage does not match the settings  (Read 773 times)

Bluemate

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Ink coverage does not match the settings
« on: February 02, 2017, 01:22:47 am »
Hi there,

This is my first project with Scribus and I've created a simple visit card, with a coloured shape as background, a logo image and a text area above this shape.

The shape is black on the first 2/3 (from the left) and then for the last 1/3 I've set a color gradient going from black on left to red on the right. It looks great on the screen. If I export it as a .pdf the gradient become...  :-X :-\ well a mixture of grey not looking good at all.

So I exported as a .jpeg image since the compagny who will print the cards accept this type of file as well and previous prints came out great like that.

Now my problem is that the Mr. from support at the printing compagny is keeping telling me that they cannot send it to print because the black area of my project (the black part of the above mentionned shape) has an ink coverage over 300%. He show me a print screen of a tool mesuring a total of 324% ink coverage.

I've checked everything I could but don't understand where the problem come from. There is no other lyer below or above this black shape and the color I used is a black composed of C60% M40% Y40% K100% which if I count it right comes to 240% which is far from the 324% told by the printer.

Could someone provide me with hints ? What is going on with that ink coverage here ?

Thanks


Nermander

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Re: Ink coverage does not match the settings
« Reply #1 on: February 02, 2017, 05:49:04 pm »
A JPEG cannot (as far as I know) contain CMYK data, thus your JPEG is most likely RGB.

This means that if you used CMYK colors in your Scribus document, those got converted to RGB when you exported to JPEG.

Bluemate

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Re: Ink coverage does not match the settings
« Reply #2 on: February 04, 2017, 10:38:39 pm »
Thank you for your reply Nermander.

So this alone would explain the jump from 240% ink to 324% ??

Nermander

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Re: Ink coverage does not match the settings
« Reply #3 on: February 05, 2017, 12:20:14 pm »
No, but it could.

This has been a topic before, to be able to convert between RGB and CMYK you need color profiles. If color management is not correctly set up, or disable, Scribus will use some kind of default setting and that setting will most likely cause problem.

It is not useful to look at the colors as you have defined them in Scribus, because those numbers are before any conversion. You need to look at the numbers after conversion. Since the JPEG most likely does not contain CMYK data, the printer probably performs some additional conversion (that you have no control over).


My advice is: If you do not fully understand color management, stick to RGB colors and possibly spot colors. With color management, there are way to many things that can go wrong.

(I personally understand enough about color management to understand that I need to learn more before I try to use it...)

utnik

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Re: Ink coverage does not match the settings
« Reply #4 on: February 05, 2017, 04:36:59 pm »
hi bluemate

if you really sent a .jpeg file, it looks as your printer did something wrong while converting to process colours.
rgb doesn't define ink coverage – it defines light values.
the ink coverage is calculated in the conversion to the print color profile – and a full rgb black (no light) wont be more than the maximum coverage allowed by the output profile.

utnik

Bluemate

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Re: Ink coverage does not match the settings
« Reply #5 on: February 09, 2017, 01:55:04 pm »
Thanks for your answer guys.

Well, yes the color management was activated and the color profil for CMYK was setup to ISO coated v2 300%.

And now I've exported to a .tiff image, which if I'm right can contain CMYK data, but the printer keep telling me the same. The black shape get to a 324% ink coverage  :-X

a.l.e

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Re: Ink coverage does not match the settings
« Reply #6 on: February 09, 2017, 03:26:13 pm »
AFAIK, the export to images is only for preview purposes.

export to pdf if you want to use the result for production.

if you need other formats, you'll need to further convert the PDF.
with a tool that retains all the settings you did.

but i'm not 100% sure of it.

please check the TIFF you got and see if the CSS profiles are in there / if it's indeed a CMYK image with all the characteristics you expect from the settings you have defined.
and please report back about your findings.

Nermander

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Re: Ink coverage does not match the settings
« Reply #7 on: February 11, 2017, 09:22:50 pm »
Bluemate, did you read what utnik wrote?

if you really sent a .jpeg file, it looks as your printer did something wrong while converting to process colours.
rgb doesn't define ink coverage – it defines light values.
the ink coverage is calculated in the conversion to the print color profile – and a full rgb black (no light) wont be more than the maximum coverage allowed by the output profile.

What utnik describes here is not something that Scribus is involved in, it is what the printer does.

 

palmate