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aTomician
aTomician
Inspiring
October 20, 2016
Answered

Transparent PNG background prints as semi-transparent

  • October 20, 2016
  • 4 replies
  • 67260 views

I've designed a flyer in Illy which has some PNG's with transparent background.  When I print this out, all the PNG's have a faint, white, semi-transparent background where they should be fully transparent.  I've tried changing several print options as below:

Default print (setup for best quality print)

- Results in the faint white backgrounds as described

Default print, but  Advanced > Overprints set to "Discard"

- Results in the faint white backgrounds as before

Default print, but  Advanced > Print as Bitmap checked

- This prints out correctly!  However what seems strange, is that instead of the page being slightly darker, the whole page colour is the same colour as where the transparent PNG's had lightened it in previous printouts.  Ie, the page colour is the same colour as the "transparent" PNG backgrounds, where the PNG background was lighter in comparison to the surrounding page background.

Default print, but in the printer setup preferences, I changed the Print Finishing option to "Raster"

- Same result as checking the "Print as Bitmap" box, except slightly more vibrant overall

Tried saving as PDF and print from Acrobat with same print settings

- Results in the faint white backgrounds as described

Tried changing document colour mode to RGB

- Results in the faint white backgrounds as before

Does anyone know why this does this, or any suggestions as to what makes this happen?  In the default, the color handling is always set to "Let Illustrator determine colors".  Does this have anything to do with the "Document Raster Settings" in the Effects panel?  I've come up against this issue several times, and in sending files to print, a couple of printers we've used have had the same issue, but others don't seem to.

Any advice or help would be appreciated.  I can use the "Bitmap" option, but I'd like to know if I'm doing something wrong or if there's a problem with my workflow.

Correct answer John Mensinger

Tomy-rex wrote:

I'd like to know if I'm doing something wrong or if there's a problem with my workflow.

There's a problem with your workflow because you're doing something (several things) wrong.

  1. You're using the wrong image format for printing. PNG and its transparency are not intended for print-destined workflow.
  2. Wrong choice #1 is compounded by the fact that you're using the wrong application for page layout. InDesign is much better equipped for mixing raster elements, vector elements, color, and transparency, in page layouts destined for print.

Sussing out the exact nature and direct cause of your output problems would require first-hand analysis of the file(s), but I suspect your RGB image files with PNG transparency are in "transparency blend space" conflict with (the colors used in) the underlying content. Perhaps the transparent image areas are interacting with spot colors. The color modes of the document and all the vector objects in it are in play and likely mix-mismanaged.

You might be able to save it by flattening transparency and/or processing to PDF before printing (as opposed to printing directly from Illustrator), but the particulars of how you'd do that are dependent upon exactly what's in the file.

4 replies

A
amandatonco
Participant
November 13, 2019

I had this same problem and was able to resolve it. After finishing the document in illustrator, you have to save the file as a JPG with maximun resolution, and after doing so, print the file. This will blend all of the layers-properties and you won't be able to see the transparent box. Supposedly this happens because the PNG is in RGB format and the drawing is in CYMK (or viceversa), the JPG format unifies the file.

    A
    amandaj30549547
    Participant
    January 17, 2020

    Thank you!!!  This solution worked for me.

      aTomician
      aTomicianAuthor
      Inspiring
      October 21, 2016

      Just tried creating 2 new documents, one with Illy's default "Print" profile, and the other with the default "Web" profile.  In both of them, I drew a square box as a background, and gave the box the same colour - not a spot colour, I used the colour picker and then copied the colour values across.

      In both documents, I placed the same 2 images, and printed both documents out.  The images in both documents had same the faint background where they should be transparent, so the RGB colour mode obviously makes no difference either.

      Regards, aTomician
      aTomician
      aTomicianAuthor
      Inspiring
      October 20, 2016

      Having got a moment to call my own, I decided to upload some examples of what I'm doing:

      1. This is the artwork - screenshot straight from Illy.

      2. This is the scan of the default print.

      3. This is a scan of the print, printed with the "Print as bitmap" option checked.

      Print as bitmap and the "Raster" print option in the print preferences are the only options i can find that make a difference to the way it prints.  Hope these help to show what I'm seeing.

      Glad of any comments

      Regards, aTomician
      PrepressPro1
      PrepressPro1
      Legend
      October 20, 2016

      Can the PNGs be opened in Photoshop and saved out as native Photoshop file and relinked into Illustrator?

      aTomician
      aTomicianAuthor
      Inspiring
      October 21, 2016

      I just tried experimenting.

      I opened up one of my saved PSD images where I had cut out the product as a clipping mask.

      Saved it as a PNG, and then also tried the Export function and tried the save for web option.

      I placed the PSD file, the saved PNG and the exported PNG alongside each other in a file.  Printed the document out on a plain red CMYK background.  All 3 images had the faint background to them.

      Someone else mentioned TIF files in another post.  In some way it felt like I was going back to the Ice Age and pulling out woolly mammoths, but I tried saving as a TIF anyway.  Same thing happened.

      Note that this is all without any spot colours etc.  Nothing is set to overprint.

      My conclusion so far is that any kind of image type with transparency will print out with the transparent part of the image being slightly opaque, rather than fully transparent - UNLESS printed with a bitmap / raster option checked somehow.

      Regards, aTomician
      John Mensinger
      Community Expert
      John MensingerCommunity ExpertCorrect answer
      Community Expert
      October 20, 2016

      Tomy-rex wrote:

      I'd like to know if I'm doing something wrong or if there's a problem with my workflow.

      There's a problem with your workflow because you're doing something (several things) wrong.

      1. You're using the wrong image format for printing. PNG and its transparency are not intended for print-destined workflow.
      2. Wrong choice #1 is compounded by the fact that you're using the wrong application for page layout. InDesign is much better equipped for mixing raster elements, vector elements, color, and transparency, in page layouts destined for print.

      Sussing out the exact nature and direct cause of your output problems would require first-hand analysis of the file(s), but I suspect your RGB image files with PNG transparency are in "transparency blend space" conflict with (the colors used in) the underlying content. Perhaps the transparent image areas are interacting with spot colors. The color modes of the document and all the vector objects in it are in play and likely mix-mismanaged.

      You might be able to save it by flattening transparency and/or processing to PDF before printing (as opposed to printing directly from Illustrator), but the particulars of how you'd do that are dependent upon exactly what's in the file.

      aTomician
      aTomicianAuthor
      Inspiring
      October 20, 2016

      Hi John,

      Thanks for your reply.

      1. If I don't use PNG for my printing, I'm at loss as to how I can print a cutout picture with graphics added around it, and not get an ugly square background from the image!  The page is red, so having a white square background to the image wouldn't look great!  If you had an image of a product on a white background, can you recommend how to incorporate the image of the product into a print design, without including the white image background around the product?

      2. I am not as comfortable with InDesign as with Illy, however I would use InDesign for a multiple page document.  This is a single page flyer and is graphic heavy, which to me makes a lot of sense using Illy.  I would like to say that this problem doesn't happen the whole time, but on some documents, every PNG I use will show this faint background.

      I have saved it to PDF using print presets and web presets, but when I print these PDF's from Acrobat, I get exactly the same results - the faint white backgrounds.

      I'll have a look at the general colours, I don't think there are any spot colours in use, but will check.

      Regards, aTomician
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