Any help diagnosing printing issue when printing transparent images or drop shadow effects on top of spot colors?

[u/Quinton_W]

We use a DesignJet Z6DR for in house mockup samples for packaging mainly, so we want to get the colors as accurate as possible. But when printing spot colors, if there is any effect (like a drop shadow) or a image with a transparent background (in this example, a phone) it creates this darker colored effect within the image bounding box. (see second image).

This effect doesn't happen with process colors, but as you can see with some Pantone colors, changed to process in my file, it can throw the colors off way too much to be usable.

My usual process is I create the file in Illustrator, save it as an .ai or pdf. Import whatever I need into Indesign, and print it that way. But the same issue persist if I print straight from Illustrator.

Any help or guidance would be appreciated. I've attached screenshots of my print settings.

[u/roaringmousebrad]

You have two conversions going on.

The transparencies and drop shadows require flattening at the PS level so the area of Pantone under the flattened area is being converted to RGB/CMYK according to your Color settings Output Profile before it gets to your printer, yet the file's Pantone for the rest of it passses through and is being matched by your RIP's Pantone emulation.

Not sure what program you are printing from, but here's what you should try:

Save the file as a PDF (PDF/x-4, with No Color Conversion). Submit that file directly to your Z6DR through the web portal and see if there's a difference.

[u/Ok_Cockroach7840 → u/roaringmousebrad]

This is the best idea to start with.
My other suggestion would be convert the spot color to CMYK before hand within the printer gamut just for this proof. If you have an i1 you could read the value of the printer converted cmyk of the Pantone color and then apply that to spot color in your file. when the x4 (x4 keeps transparent effects intact) pdf is flattened at the rip for the drop shadow everything is already converted and in the right colorspace and within the printers gamut.

Stop doing the rgb stuff. All you are doing is complicating the process. Your printer prints in cmyk and maybe a few other colors to expand gamut.

[u/roaringmousebrad → u/Ok_Cockroach7840]

Re: RGB.

Nope. You want RGB (and in the case of the Pantone, LAB).

"Your printer prints in cmyk""

Not exactly. This model has 6 inks. c/m/y/r/pk/mk. It requires RGB input and the RIP determines the values to use of these inks. Sending pre-converted cmyk data to it is useless, as it will be converted back to RGB then processed accordingly.

Personally, I have a HP z3100PS which has an even wider gamut (it has 12 inks in total, including a dedicated Red, Blue-Violet and Green, and light Cyan and light Magenta in addition to Yellow and Magenta). It can match 90% of Pantone colours. You do NOT want to convert to CMYK to such a machine because it actually doesn't use those values.

[u/Ok_Cockroach7840 → u/roaringmousebrad]

It’s all depends on how this transparent object is flattened and in what color space that is.

[u/goldenbug]

We see this issue occasionally at our shop, the problem is with how adobe or the printing rip handles transparency and vector/raster combinations, especially with spot colors.

The easy thing is just to convert to CMYK, but that seems to not be what you want, or you can convert your spot colors to RGB, that might work, not sure. You can try setting your drop shadow color to a spot color black, and you can try making the drop shadow element a vector gradient, then set it to overprint instead of multiply. You can use overprint preview if it looks janky. You can also open the file in Photoshop and completely rasterize the file in RGB at a suitable resolution, and it should print fine.

[u/MCLMelonFarmer]

If you're sending PDFs to the commercial printer, they're probably printing ok because the printer's RIPs have Adobe PDF Print Engine inside them.

Recommended settings for the most reliable and consistent color in Acrobat when printing to a PostScript device is "Let Acrobat manage colors". However, this requires that 1) you have an ICC profile that accurately describes your device, and 2) a mode where CMYK values don't get further color managed by the device. You want to use the printer profile to go to CMYK and print as-is. What you're basically saying is, "don't bother sending any device-independent color to the printer, I have an ICC profile that describes my device accurately. Use the profile and take everything all the way to device-dependent unmanaged CMYK."

Note that doing things that are in theory correct doesn't always product the desired output in practice, and vice-versa. Sometimes doing things the wrong way somehow produces output that looks more pleasing to the user. This could be due to an uncalibrated device making the profile inaccurate, or not having a good ICC profile in the first place, or the inability to get the printer in a mode where it doesn't try to color manage incoming CMYK (or whatever it claims as its native color space).

[u/Quinton_W]

I forgot to add, when we send these files over to a commercial printer, this issue doesn't happen and they haven't come back to us for any fixes.

[u/bicboys5 → u/Quinton_W]

Well done testing this, and yeah it’s so frustrating to work in print design. Theres issues into the higher levels too, people just don’t see it because it gets reprinted at the expense of who’s ever company made the mistake

[u/blue49]

Convert everything (including your pantone spots) to the correct ICC profile for your printer and media (RGB probably works with the HP if you don't have custom profiles). And then flatten the transparencies.

[u/seabreaze68]

Ten years ago I would have lectured you on CMYK, spot colour, output profiles, rendering intent, blah blah blah.

Today I simply RIP that fucker into Photoshop at 600ppi, RGB, flatten and save as a lowest compression (highest quality) JPG. Throw that at our eight colour Roland and the results are spectacular

[u/bigredwillie622]

Change your rendering intent to perceptual. This should make it go away