Tag Archives: PDF

Why Slices and Spot Colors Don’t Mix

4 Dec

One of the many stumbling blocks of print design is the interaction of transparency and spot color.  It’s a rather demanding subject and impossible to cover completely in a single blog entry.  So, let’s confine our discussion to the realm of the PDF/X1a.  And, just to keep things simple, we’ll use the same BPI banner art from the previous blog posting.

First, let’s take a look at the Spot_Color screenshot below.  As you can see, the BPI logo, headline and web address all share the same value, a variation of the legacy version of Pantone Reflex Blue-Coated spot color.  Notice that the spot color objects are uniformly close to the top of the stacking order with only solid objects like the white BPI and green leaf with a solid white stroke above them.

Now, lets take another look at the PDFX/1a version of this art (screenshots Spot_Color_PDF and Spot_Color_PDF_Outlines). Despite the lack of transparency. The automated PDF engine has created several slices and clipping masks. But because there are no interactive transparent objects, the slices still retain their original color value of PANTONE Reflex Blue 2X CVC 2.

    

Now, let’s screw this up. Let’s add a drop shadow to the white portion of the BPI logo. We’ll use the default drop shadow values (see Drop_Shadow screenshot below).

Please take note of the transparency values of Mode and Opacity. Next, we’ll save this art as a PDF version X/1a . Now let’s take a look at the results, see the Missing screenshot below.

Our drop shadow appears to have vanished and a few chunks of the logo have changed colors to the background blue. But wait, there’s more. The bpi has shifted away from a true white of 0 cyan, 0 magenta, 0 yellow, 0 black to something a little different – see Color_Shift screenshot.

If you think this is disappointing, take a look at how Acrobat views the same art (Acrobat screenshot). If you tried to print this file in a conventional RIP, the only thing you could count on is NOT getting what you wanted.

So how do you avoid this. Either avoid overlaying any transparent elements over objects with spot color or employ a different Acrobat preset. Just for example, here’s what the High Quality Print preset looks like – see HiQual_Preview screenshot. At last, everything looks exactly like it’s supposed to.

But the big question is, will the new PDF print correctly? Only your service provider can answer that question. And that’s going to depend on the capabilities of their RIP and print devices. If you have any doubts, call and ask. Everybody likes getting things right the first time.

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Behind the Scenes – PDF Challenges

17 Apr

Over the years there have been a number of updates to the PDF file format.  During that time, we have documented steps to improve PDF printing to your KIP device.

If you are using the Windows driver to print PDFs, you must use the KipScript part of the driver.


If you want to have this default to KipScript, you will have to change this option on the server under “Devices and Printers.”  Keep in mind that most of the time KIP defaults to KipGL after installation. This seems to be the prevailing issue with PDF printing and you should always check this first.

Basically, if you print from Adobe or any other PDF reader, use KipScript. Printing from AutoCAD Revit is when KipGL should be used.

Also, the port for the Windows driver must be set to 8421. If the driver is shared from a server, you need to check it there.

Follow these steps to check it.
1. Open the Start menu, then go to “Devices and Printers.”
2. Right click on the printer and select “Printer Properties.”
3. Click on the “Ports” tab and scroll down until you see the plotter IP address.
4. Click “Configure Port” and you should get a window like this.

5. Check the Port Number and make sure it’s set to 8421. Click OK to close once finished.

Make sure that the monpath1/Request folder is cleared of all old print jobs. Then, check the WinUntd.ini file and make sure that if you have a newer controller this line reads TRUE. MultiThreadPDF=True. Remember to close Unattend before you clear the queue and change any .ini settings.

Some things to consider to speed up PDF processing…
If you are using the Windows driver out of Adobe for most or all of your PDF printing, it is recommended to check the box “No Transparency” in Printnet’s Printer Config. This shuts off the controller’s “Flattening” process, which is used when a PDF file has layers. Think of layers as having multiple images layered on top of each other. In order to print the image, the software has to combine these images together to get the proper output. This greatly increases processing time for each PDF file that has layers enabled.

When printing through the Windows driver, the driver flattens the image out before it sends it off to the printer. As the raw print job is already flattened, it doesn’t need to go through the flattening process again on the controller, so having this box checked turns off that function, decreasing processing speed and increasing print speed.

However, if you are using Request or Printnet for most of your PDF printing, this box should be unchecked to keep the function turned on. The Request software DOES NOT flatten PDFs, so the controller has to do the flattening and must have this function enabled by having the box unchecked.

If you start seeing large black boxes on your prints, this means that you probably sent the PDF from Request and the “No Transparency” box was checked, turning off the flattening function. The controller cannot flatten the PDF so it turns some layers into black blocks. Because most people use a mix of Request and the Windows driver, this box usually should be left unchecked. It slows processing time down, but ensures you get the proper output. If you would like to see faster processing times, you can use the Windows driver and check mark the “No Transparency” box. Or you can always send flattened PDFs without layers.

How to Have a Bulletproof Workflow

21 Feb

So how do you manage your projects so you get predictable results?  Answer: manage the two different forms of digital assets (raster and vector) so that the color range of your print file fits within the range of your output device.  This is sometimes called a CMYK neutral workflow.

Let’s talk a little bit about print files.  The basic types of print file are the JPEG, TIFF, EPS (encapsulated postscript) and the PDF aka…Acrobat file.  JPEG’s and TIFF’s are strictly for raster/image/photo file types.  EPS and PDF/Acrobat files can contain raster and vector art.  You may have heard of postscript (PS) files, but it’s used less and less these last few years. Postscript has essentially been replaced by encapsulated postscript (EPS).  For the sake of a more compact post, let’s concentrate on the EPS and PDF file types.

There are several structural differences between the two file types.  But, the main difference is ICC profile support. The EPS file does not support the inclusion of ICC profile data; Acrobat does.  And this is why so many printers and large format service providers use EPS as their preferred print file.  What your output provider wants to avoid is a conversion phenomenon akin to double-dipping.  Most RIPs look for profile data.  When they find it, they will (unless managed by the RIP operator) apply another instance of image compression to the print file to fit the color range of the specified ICC.  In other words, your compressed photo gets re-compressed.

ICC’s are not really a perfect model for vector art.  Think back to the diagram, InkjetVsSWOP.png in a previous post. If you strictly interpret the 3D lab image for offset printing, you would conclude that a perfect green (100% cyan and 100% yellow) can’t be achieved on an offset press.  We’ve all read enough magazines to know you can get bright yellows, reds, greens and rich colors from offset printing.  So, what’s going on here?

You’ve probably guessed it.  At some point, your output provider is discarding the ICC profile information.  And it sounds like heresy after all you’ve heard about the necessity of working with agreed upon profiles for color management.  But don’t let your head explode just yet.  Let’s get back to image management.

Image management is simply making sure all your elements (text and photos) conform to the range of your final output device.  Pick the appropriate workflow and work with the end product in mind.

Here are a few tips for you budding graphic designers:

Consider color conversion a one-way street for your vector art.  Your classic light blue (100% cyan) will appear similar when you switch your file to RGB. But, if you were to switch your file back to CMYK the values are transformed to roughly 70% cyan and 14% magenta.  We always make my vector art in CMYK. That way, if we have to make an RGB graphic from it we don’t have to worry about missing a corrupted value for print.  Also, our web graphics will more closely resemble my print files.

Do NOT convert vector art to an ICC profile. Occasionally, you’ll see this option when “Placing” (linking to an external file) or pasting other art into your current working document.  The color values will shift in an unpredictable manner, just think back to what happens to 100% cyan when you change it to RGB and then change it back to CMYK.

Make sure all your scans, photos and Photoshop art share the same profile and color space before assembling your art.  We know most applications have a “Convert to Profile” export option.  This is not a reliable way to work.  When you employ blind processing, you’re asking for an unpleasant surprise. You’re much better off doing the image work yourself.

Use TIFF’s instead of JPEG’s (and ZIP compression when exporting to PDF). Once upon a time, JPEG compression was the recommended way to save images for print due to limits on memory and processing power. One way JPEG compression controls file size is by consolidating color together within a certain range of values.  You may have heard of JPEG’s as a lossy (or lousy, if you’re as picky as we are about image quality) form of compression.  If you’ve ever wondered where those boxy looking squiggles or blocky halos around text came from in digital art, now you know.  In addition, the default compression for saving as a PDF is JPEG.  When you pile JPEG compression on top of JPEG compression you’re just asking for an unattractive result.  We now have more memory, much more powerful CPU’s, graphics cards and RIP software.

If you want more information on JPEG compression, check out the Wikipedia page: http://en.wikipedia.org/wiki/JPEG

And finally, CYA!  Conserve Your Assets!  Always keep customer supplied originals, unaltered.  The client may ask for them at some point.  You may need to compare appearances or justify edits and output with your client standing over your shoulder. CONSERVE YOUR ASSETS; it bears repeating. 🙂

PS: You may have noticed the inclusion of the Light Jet and Durst Lambda under Large Format RGB. Conventional large format inkjet imaging has progressed to the point of photo quality output which can (IMHO) outperform the Durst and Light Jet machines.  Also, new archival, acid-free papers and fade-resistant inks are eliminating the advantages of large-format photo output for lifespan.

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