Highlighted

Multiply vs PSD with Transparency in Regards to Black Blacks, Knockouts and Color Separation?

New Here ,
Oct 27, 2020

Copy link to clipboard

Copied

Hello InDesign Wizards!

 

I'm setting up a document with comics pages and I need a hand. These are intended for print.

 

Presently I have a Photoshop file with color and a Photoshop file with black and white (lineart) that I layer on top of the color file in InDesign.

 

1. I want the color file to be visible under the black lineart file, and the white pixels in the lineart file to be completely transparent.

2. I don't want the black lines to "knock out" the color underneath them.

3. I want the black lines to be black, and not transparent at all.

 

Currently I have the black and white lineart file set as a bitmapped Photoshop file. When I bring it into InDesign, I place it on top of the color file and I set the transparency to "multiply." This way, the color file underneath can be seen, and when I look at the color separation panel, the black is not knocking out the color.

 

However, when I export a PDF, it looks like it may be possible to see some of the variations from the color file coming through from under the black, particularly when there's a field of black.

 

I'm wondering if I should be setting this file up in a different way. I've tried creating a non-bitmapped lineart PSD file where only the black lineart is present, where I've removed the white pixels and they're instead transparent. But when I overlay this on top of the color file in InDesign, when I look at the separation layer, the black is knocking out the lines on the color file.

 

Any help would be greatly appreciated!

 

S

TOPICS
Print

Views

109

Likes

Translate

Translate

Report

Report
Community Guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more

Multiply vs PSD with Transparency in Regards to Black Blacks, Knockouts and Color Separation?

New Here ,
Oct 27, 2020

Copy link to clipboard

Copied

Hello InDesign Wizards!

 

I'm setting up a document with comics pages and I need a hand. These are intended for print.

 

Presently I have a Photoshop file with color and a Photoshop file with black and white (lineart) that I layer on top of the color file in InDesign.

 

1. I want the color file to be visible under the black lineart file, and the white pixels in the lineart file to be completely transparent.

2. I don't want the black lines to "knock out" the color underneath them.

3. I want the black lines to be black, and not transparent at all.

 

Currently I have the black and white lineart file set as a bitmapped Photoshop file. When I bring it into InDesign, I place it on top of the color file and I set the transparency to "multiply." This way, the color file underneath can be seen, and when I look at the color separation panel, the black is not knocking out the color.

 

However, when I export a PDF, it looks like it may be possible to see some of the variations from the color file coming through from under the black, particularly when there's a field of black.

 

I'm wondering if I should be setting this file up in a different way. I've tried creating a non-bitmapped lineart PSD file where only the black lineart is present, where I've removed the white pixels and they're instead transparent. But when I overlay this on top of the color file in InDesign, when I look at the separation layer, the black is knocking out the lines on the color file.

 

Any help would be greatly appreciated!

 

S

TOPICS
Print

Views

110

Likes

Translate

Translate

Report

Report
Community Guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
Oct 27, 2020 0
Most Valuable Participant ,
Oct 27, 2020

Copy link to clipboard

Copied

Use PSD files with transparent backgrounds. Set a blend mode of multiply for the black line art file.

Likes

Translate

Translate

Report

Report
Community Guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
Reply
Loading...
Oct 27, 2020 0
Adobe Community Professional ,
Oct 27, 2020

Copy link to clipboard

Copied

How are you viewing the PDF exported from InDesign? Some PDF viewers fonts honour opacity modes. Some don't render them properly. Use Acrobat Pro and separation preview. Better yet, combine the images in Photoshop and bring them in as a single image.

 

I would also try using Live Trace in Illustrstor and setting the artwork to overprint in Illustrstor. Make sure transparent parts are transparent and not white. 

Likes

Translate

Translate

Report

Report
Community Guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
Reply
Loading...
Oct 27, 2020 0
Adobe Community Professional ,
Oct 27, 2020

Copy link to clipboard

Copied

Bitmap images—Black and White in the ID Links panel—can be set to Overprint in the Attributes panel, and if you set the parent frame’s fill to None the white pixels will effectively become transparent even though there is no transparency on the page.

 

So a placed Bitmap with its parent frame set to white:

 

Screen Shot 6.png

 

Set to [None]

 

Screen Shot 7.png

 

The Bitmap selected and set to knockout:

 

Screen Shot 8.png

 

The bitmap set to Overprint in the Attributes panel with the Black plate hidden:

Screen Shot 9.png

Likes

Translate

Translate

Report

Report
Community Guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
Reply
Loading...
Oct 27, 2020 0
Adobe Community Professional ,
Oct 27, 2020

Copy link to clipboard

Copied

However, when I export a PDF, it looks like it may be possible to see some of the variations from the color file coming through from under the black, particularly when there's a field of black.

 

Also, offset inks are somewhat transparent, so when Black overprints a color InDesign and Acrobat will show the black only transparency effect. Can you show a screen capture?

 

Black overprinting 2 colors with an uncoated CMYK profile assigned to the document. You would expect this to happen on press printing to an uncoated sheet:

 

Screen Shot 11.png

Likes

Translate

Translate

Report

Report
Community Guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
Reply
Loading...
Oct 27, 2020 0
New Here ,
Oct 28, 2020

Copy link to clipboard

Copied

Thank you Scott and Bob for your earlier replies! I'll look at my PDF again in a couple of different viewers.

 

Rob, your reply is just what I was looking for. I hugely appreciate the thorough screenshotting and explanation. I'm going to try to replicate this now.

 

Regarding transparency when it comes to black overprinting: I recognize this is the nature of offset. If I color the bitmap with Registration or a Process Black (K100), will this reduce transparency at all? Or is that what we're seeing in this example?

Likes

Translate

Translate

Report

Report
Community Guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
Reply
Loading...
Oct 28, 2020 0
Adobe Community Professional ,
Oct 28, 2020

Copy link to clipboard

Copied

You can’t use Registration because it would create a total ink and drying problem on press.

 

If you add any CMY to the black lines they will no longer overprint, but in that case why bother to separate the black line and color into seperate files? If you create and edit the art in an RGB editing space and make a conversion to CMYK the black lines will be converted the destination CMYK space’s black point—i.e. GRACol Coated Perceptual would convert to 85|75|60|100.

Likes

Translate

Translate

Report

Report
Community Guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
Reply
Loading...
Oct 28, 2020 0
New Here ,
Oct 28, 2020

Copy link to clipboard

Copied

Registration: Ah, right... it's been a while since I set up a print file like this. So definitely will avoid that.

 

I forgot to mention in my original post that one of the reasons I have the lineart on a separate layer is so I can have it at a higher dpi than the color. The lineart is 1200 dpi, while the color is 600.

 

I guess I'm not sure what you mean that it wouldn't overprint if I add CMY. Is "Overprint" reserved for pure black? Now I'm asking basic print questions, not InDesign specific I suppose, so I understand if you can't get too deep into this topic with me. Thanks either way.

Likes

Translate

Translate

Report

Report
Community Guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
Reply
Loading...
Oct 28, 2020 0
Adobe Community Professional ,
Oct 28, 2020

Copy link to clipboard

Copied

 Is "Overprint" reserved for pure black?

 

[Black] will only overprint the CMY plates when their value is set to 0, so with CMY set to 0:

 

Screen Shot 12.png

 

If I set Cyan to greater than 0 Black does not OP my 100 cyan fill (note that the document’s CMYK profile here is Uncoated GRACol and the black appears gray, which would be the case on and uncoated sheet.

 

Screen Shot 13.png

 

If CMY is set to 1 black knocks out:

Screen Shot 14.png

 

A rich black also knocks out but its appearance changes because of the extra CMY underneath

Screen Shot 15.png

 

 

 

so I can have it at a higher dpi than the color. The lineart is 1200 dpi, while the color is 600.

 

I doubt the difference between 600 and 1200 ppi will be noticeable and worth the extra effort. There will still be some halftone interference where the screened color meets the black line, so unless you are running an exceptionally high resolution line screen, you would be better off with a composite 600ppi.

 

You might want to get a high res proof or press test comparing the resolutions. Also, watch out for down sampling in the workflow. A default export to PDF will down sample to 300ppi, and it is common for printers to down sample in their RIP—if you are running extra resolution and want it to output make sure the printer knows.

 

 

Likes

Translate

Translate

Report

Report
Community Guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
Reply
Loading...
Oct 28, 2020 0
Adobe Community Professional ,
Oct 28, 2020

Copy link to clipboard

Copied

Hi SophieWork,

you write:

 

"…However, when I export a PDF, it looks like it may be possible to see some of the variations from the color file coming through from under the black, particularly when there's a field of black. …"

 

It would help to see a screenshot of a typical piece of artwork where this happens ( InDesign document with Overprint Preview enabled ).

 

Setting black line art to overprint would help for "thin" strokes, yes. But in case of black fills it would not, because the colored motif below will show through, its Cyan, Magenta and Yellow components. In that case the Black of the line art should be enriched with a neutral mix of Cyan, Magenta and Yellow percentages. But not too much; not the maximum color that is suggested by the printing condition.

 

You could do this with all your line art, but in case of thin strokes it would depend on the quality of the offset prints if annoying effects will be visible that come from mis-registering the four printing plates. But this effect is only visible if the color motif below does consist of very light colors. It's also a question of the quality of the printing paper.

 

Regards,
Uwe Laubender

( ACP )

Likes

Translate

Translate

Report

Report
Community Guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
Reply
Loading...
Oct 28, 2020 0