Transparent Image Over Gradient in Illustrator

[Bill W]

I have attached a PDF that further describes my dilemma. I could find no way, other to rip this to film (yes we still use film) to see how the gradient was affected when overlayed by the transparent image.

We are a Prinergy shop and use TIFF Assembler Plus to check ripped files before sending them to plot, but the artifact created by overlaying a transparent image do not show. When we eventually go to digital plates we would not see this artifact until we made plates and even then it might not be that easy to see on a flexo plate.

Does anyone know a way to proof a file with a transparent image over a gradient to see if the gradient gets "hosed" before sending it to film / plate?

 

[rich apollo]

Wouldn't the problem show up in your proof? Lemme' guess, the gradient is a spot color, too.

What you're describing makes sense. Some systems can RIP and output smooth shades (gradients) at 12-bit. Imagery, however, is RIPped and output at 8-bits per channel. Anywhere that the image overlays the gradient will be converted to continuous tone imagery with too little change in the blend area to avoid banding.

Do your clients just hate you? Are you paying penance for some atrocity committed in a previous life?

 

[Bill W]

Unfortunately Rich, it does not show on my Epson 4880 with Oris rip. In this case the gradient is a process mix. The radial gradient length is about 3 inches and the values go from 0% to 10% for cyan and black, higher values for the magenta and yellow. However there is a mask that clips the gradient to a length of about 1.74 inches which stops the gradient at 4.27%. When I added the mask it fixed the problem for the magenta and cyan but not for the black. I was stumped as the values for the cyan and the black are the same.

The challenge is that the cyan has values all the way out to the edge of the mask, while the black is a skeleton black and has no values that extend to the edge of the mask. The cyan image values overwrites the gradient values to the edge of the mask, but the area in the black that has no values inside the mask allow the step artifact to manifest itself from where their values stop to the edge of the mask.

To fix this problem I could have created a second file just for the black and made a mask that clips closer to the black. However I took the easy way out and increased the end of the black gradient to 25% which, while not entirely alleviating the problem, helped tremendously and did not change the masked part of the gradient.

I am not sure if my clients hate me or I am paying for something I did in a past life as I do not remember what I did in my past life . As I get older I am discovering a challenge with remembering the early parts of this life.

I will confess that I both loathe and love artists that supply this type of art. I loathe them because they create art like this that will not print properly until I fix it; and I love them because they create art like this that will not print properly until I fix it, which allows (forces) me to learn new tricks to fix such art.

I did discover just this morning that if I rip this problem file with the curve and then add a 7% bump plate curve, I will be able to see the gradient steps in Tiff Assembler Plus almost exactly like the show on the film.

 

[Stephen Marsh]

Bill, are you using the APPE or CPSI engine in Prinergy? Is the result the same from both?

Is the PDF flattened or does it contain live transparency?

What PDF version are you refining into and does it flatten or retain transparency?


Stephen Marsh

 

[Bill W]

Stephen, PDF version is 1.5. As far as I can tell the transparency is live. I say as far as I can tell because when I try either the APPE or the CPSI engine Prinergy reports that transparency has been found and it is being flattened. I have little experience with using the APPE engine so I do not know when Prinergy should be flattening the transparency - at output?

I thought any PDF above version 1.3 has, by default, transparency preserved. Is there a setting to flatten it somewhere in versions 1.4 and above?

The photoshop file that is layered over the gradient has a transparency setting of darken in Illustrator - set by the customer. I changed it to normal and the preview in Illustrator shows the gradient being knocked out behind the photoshop file. So it appears that some sort of setting needs to be set in the transparency setting to allow the gradient to not be knocked out. Just looking on the screen between setting Darken or Multiply, it seems Multiply would be a better setting.

I did not notice this Darken setting until tonight when I was researching your transparency question - so I cannot test to see if Multiply will help with my gradient banding problem.

-Bill-

 

[CHM]

Can you share the live file?

 

[rich apollo]

Well, Bill, this file is like a trip back to the PostScript Wars. I would take the image and the blend, rasterize that mess and then work on it in Photoshop. Throw some noise into the blend to cover the banding.

Oh, and then I'd take out a contract to have the designer smacked with a cold, dead fish.

Clipping path, clipping path, clipping path...

 

[Walleye-one]

Hi Bill, not sure which version of Prinergy you are running, but if you're getting a message about pages containing transparency and pdf being flattened with both APPE and CPSI, I'd take a look at your refine template. In the normalize section, there is a setting for PDF level handling. To keep transparency live, you should be using the APPE rip (newer rip, better for live transparency) and have your setting in normalize set to "leave as is". If you use the CPSI rip (older rip, but better for flattening transparency) you want to set the level handling to "flatten to 1.3".

Cheers,
Aaron

 

[Stephen Marsh]

I thought any PDF above version 1.3 has, by default, transparency preserved. Is there a setting to flatten it somewhere in versions 1.4 and above?
-Bill-

A particular PDF version may be able to support transparency, however the file may be flattened using the transparency flattener while still retaining it's PDF version level.

What I was getting at, which Aaron later clarifies, is that I would hope that you have better results using the APPE RIP and not flattening or changing the version level. I was curious whether the PDF RIP handled this better than the old PS RIP.


Stephen Marsh

 

[Paul Santer]

Three Methods I can think of to Proof this type of issue.
1) Is to find someone with a copy of Star Proof calibrated for Flexo and send them the 1-Bit Data
2) Is to Proof the 1-Bit data with Firstproof and dial in some additional Dot Gain to accentuate the Problem.
3) The third would be to create a separate Output Ticket for Proofing Only with an increased Bump Curve so any issues like this are over exaggerated when you view the 1-Bit Data. (Not Sure how well this would work as I'm no Prinergy expert)

 

[Bill W]

Aaron, we are running v 5.2.2.1. Thanks for the tip, however changing the 1st refine to "leave as is" did not change the look of the gradient. Our corporate office was the first of our locations to have the APPE RIP and they did not feel it was very helpful, so I have not tested it until this file arrived.

Rich, I did try the old noise trick, but even as little as .5 noise left some very bad artifacst in the blend.

Here is the link for those that want to "experience" this file:

https://mpilabels.sharefile.com/d/s37f124cc1ca47a8a

 

[Lukas Engqvist]

Would it be stupid to suggest that you place the image behind, the spot gradient in the front with an overprint if it is spot (I believe you said it was originally multiply so if CMYK Multiply the gradient over image. For multiply stacking order isn't important), even if you print it first that stacking order may be better for the RIP.

But the image isn't quite clean. (saw that before your white text over looked funny) This is an analysis with Astute graphics InkQuest (gradient hidden)

 

[CHM]

I have send your file trough our rip and made 8bit tiff's, you can download them here: https://dl.dropboxusercontent.com/u/275719/FTPlinks/test (imported).zip

 

[Bill W]

CHM - thanks but those TIFS are not screened. However if you bring the black tif into photoshop and add a curve you will see that the same gradient steps show. Based on that I think your file would also show steps when screened.

 

[tommrz]

switch to the appe rip

 

[tommrz]

your blend also goes to 0 in all 4 colors at the center, you are going to get some nasty drop off

 

[Bill W]

Yes the blend does got to 0%. We are using maxtone and hyperflex to mitigate the drop off. However while those two technologies help the drop off, they still to not mask the gradient blend steps.

 

[Lukas Engqvist]

Have you tried making it a Spot colour in Illy and then using Acrobat or RIP to convert to CMYK?

 

[Bill W]

The gradient is a CMYK mix with sliders set to achieve the color the customer desires. I do not think a match could be made using a spot color.

 

[Stephen Marsh]

Bill, it sounds like there are two issues:

1) When using the CPSI RIP you had an issue where the transparent image over the radial gradient created artifacts that were not visible where there was no transparent image over the rest of the gradient.

2) You are also seeing banding in a vector radial gradient when it is screened to 1 bit.

Is this correct?

Did using the APPE RIP and not flattening transparency fix issue 1?


Stephen Marsh