Problem with transparency when printing with black background - Scribus

Question

I am currently realizing a poster with Scribus (I am a beginner) and run into troubles while printing with black background.

I have several pictures with transparent backgrounds (png). First, the general background of the document was set to cyan and there was no problem. Everything printed fine. Now I switched to a black background and here started the problems. All my pictures appear on print to be frame with black which is slightly different that of the background one (not the case in the pdf).

I am printing after export to pdf using my office printer:

I tried several thing which did not work.

• Created my own black with 100% K -- no improvement
• Used Rick black -- worst: contrast is even more marked
• Downloaded Scribus 1.5 to export to PDF X-4 -- no improvement
• Checked all pictures properties for knock out properties
• Switch to overprint properties -- no improvement
• Activated color management -- but there I am not sure what to do further...

I guess it's not a transparency problem as everything works fine when background is cyan, and I am completely stuck so any help/suggestions would be welcome on this.

Thanks!

Answer 1

PNG (and RGB) can be really fine in a print workflow.

Of course, if you want to be sure that the colors are matching, you'll have to setup a color managed workflow (and activate the color profiles).

Now, you're not saying how you're printing. One important thing: always first create a PDF and then print that PDF. You should probably not directly print from Scribus.

If you're printing on a home / office laser printer, you should probably go for a PDF 1.4. You mention that you tried PDF X-4. That should also work with PNG and transparencies (as far as I know, it's based on 1.4). But the whole printing workflow should then really support PDF X-4.

On the other side, if you want to switch to a CMYK workflow, you can use a TIFF with transparencies. Or fill the background with the same color as you have in the final document (and change the frame's shape in Scribus so that you don't hide parts of your document).

Finally, I've done a lot printing on office printers with PDF 1.4, PNGs and transparencies and I never had any issues. But it was almost always on white backgrounds.

There is one thing you have to make sure: the whole printing workflow should support PDF with transparencies (or you should have a "clean" flattening at some time). When a ripper flattens a PDF, it normally does it in a "stupid" way and you simply get a solid color.

Edit (since I cannot upload files in a reply):

I've now created a transparent PNG with a black rectangle filling part of it and a black RGB shape in Scribus that is below the image. Here is the PNG file:

I cannot upload here the SLA (scribus 1.5) and PDF:

• square.sla
• square.pdf

On screen, they look fine to me. Can you try to print the PDF on your printer?

Answer 2

PNG images are RGB, they are for use on the web/rgb displays, not for print. The format doesn't support CMYK.

Use a CMYK TIFF instead, and make sure the TIFF's black background is the same CMYK mix as the black background in your document.

Answer 3

Convert the pdf to tiff, then printing works fine. For example via convert

convert some-pdf-file.pdf some-fixed-tiff-file.tiff

The tiff file will have the transparency fixed and the background if this transparent embedded image is not more black but truly transparent.

Answer 4

I have had a similar problem with transparency in MS Office apps on my HP Color Laser printer. From the screenshot you posted, I think you have an HP printer too. I played around with manual "Color Options", changing the text/graphics/photos "Neutral Grays" setting from "Black Only" to "4-Color" - don't know if all 3 need to be changed (maybe just graphics?) but this resolved the issue for me. Image attached - hope this is still useful to someone!