Rich and the PDF

By Rich Apollo

October 11, 2022

We used to have an amazing technician here who had some very opinions about PDF. I’m a designer and sort of do what I’m told and that usually works pretty well. But Rich’s background is in prepress and he doesn’t like to do what he’s told, especially not when it comes to PDF. His settings are hard won victories in the war of the tried, failed, and corrected - peppered with files lobbed from anywhere, prepared all different ways, and very seldom what they need to be. In his world, a good PDF means a job without reprints. Rich shares his thoughts and recommendations.

I have heard and engaged in many discus-sions about the right settings for creating a PDF. But there is no unique way to create the perfect PDF, just as there is no unique way to make a chocolate cake. A cupcake won’t serve every-one at a birthday party, and a whole birthday cake is tough to pack in your lunchbox. In PDFs as in chocolate cakes, what you make depends on its purpose. That very important consider-ation determines how a PDF is built.

For printing, there are a few settings that I feel strongly about and that I will go over in this article. These settings are not necessarily industry standards but reflect what has worked and also failed during my career in prepress.

- Rich Apollo, xxxxxxxxxx

General Window

In the General screen, I set the Compatibility to PDF 1.4 or better because it’s the only way to keep transparencies intact in the document (1.3 doesn’t have transparency at all). The release some years ago of the Adobe PDF Print Engine (APPE) alleviated the need to flatten transparencies in PDFs created for print. Especially when there are spot colors, flattening transparencies can have undesirable side effects, like breaking objects apart which causes incorrect trapping and inconsistent color between the vector and raster components of a single element. If spot colors are converted to process in an all ready flattened file, there can arise an overprint situation that cannot be rendered*. The unintended consequence is that elements, or parts of them, drop out of the design.

I set the Standard to PDF/X-4:2010 because this allows me to include live transparency and an Output Intent in the PDF. Having selected an output intent in your file, nothing has to be converted to the Output Intent color space when you export to PDF. You can even include RGB elements with RGB profiles embedded in a PDF with a CMYK Output Intent. The Output Intent will act like a simulation profile with color man-agement happening downstream. A typical ICC color transformation goes like this:

Source color space ▶ Profile Connection Space (Lab*) ▶ Destination color space

With an Output Intent, or a Simulation Profile, the ICC color transformation goes this way:

Source color space u Lab* uSimulation Profile u Lab* u Destination color space

Let’s say you built a document in the Adobe 98 color space and included an Output Intent profile for the SNAP 2007 (coldset newsprint) color space. When you later convert, the Output Intent will be honored during that conversion and your file will be limited to the smaller gamut that is produced in the SNAP 2007 color space. In spite of being in the GRACoL color space, your file will look like coldset newsprint. This, of course, means that it is important to check whether there is an appropriate output intent in your document.

Under Options, there are only a couple of items that we may want to include. Embed Page Thumbnails is not something that is useful for printing but Optimize for Fast Web View speeds up on-screen drawing. You do not need to check Create Tagged PDF. This setting includes a set of tags to work with assistive devices for people with disabilities including, for example, screen readers for those with vision impairments.

Export Layers offers three self-explanatory options: All Layers, Visible Layers, and Visible and Printable Layers. “Layers” here refer to InDesign layers. This determines what’s going to be exported.

Create Acrobat Layers mimics the layer structure of your InDesign document in the PDF. This can be very useful for documents with multiple versions like different languages. A layered PDF eliminates the need for multiple documents in this situation. However, consult your print provider before using this feature. If they are equipped to make use of layered PDFs, selecting this feature will save them a great deal of time and reduce the complexities of file management. But if they cannot handle these kinds of files, you will have given them a lot of extra work. Exclude all interactive elements, bookmarks, hyperlinks, guides, and non-printing elements.

Compression

When selecting the PPI, the gen-eral rule of thumb for image reso-lution for Color Images is 2 times the final screen ruling. If a project is being printed with a 150 lpi screen ruling, then images should have a resolution of 300 pixels per inch. With a 175 lpi screen ruling, images would be 350 ppi, and so on. In reality, 300 pixels per inch is usu-ally adequate, even when printing with stochastic screens screening. I keep Monochrome Images at high resolutions because this category includes all those black and white images that we wish were vector art.

The default values for downsampling are 300 ppi for images above 450 ppi but I give them the same value. I figure that, if I need 300 ppi, then I should choose 300 ppi, not a range like 300 to 450 ppi.

Compression is something that I have strong opinions about. Adobe PDF’s default setting is JPEG compression which is not a good choice for print. JPEG is a lossy compression structure. Lossy is a data compression method that compresses by discarding data, sometimes introducing artifacts that can be seen in the final product. ZIP, LZW, and CCITT are all safe compression methods to use.

JPEG 2000 is a lossless compression structure that may not be supported on all RIPs.

All images should be in 8-bit color. Imagery in 16-bit color is good for color editing, but will cause many RIPs to fail. The last switches, Compress Text and Line Art and Crop Image Data to Frames are ways to reduce file size.

Marks and Bleeds

Unless your printer asks for them, marks aren’t needed. If you include crop marks, make sure that they sit completely outside of the bleed. Printers almost always request a minimum of 1/8” bleed (.125”), but Adobe has left the default offset for marks at .0833 inches, or 6 points which put the marks in the bleed. In order to be at the edge of the bleed, select .125” in Offset. I have never need-ed any of the other options listed here. The printer will be placing each page of your document into an imposition system where the necessary crop marks, registration marks, and color bars will be added.

Options in the Marks and Bleeds screen were important in the manual stripping days. Today, stripping and imposition have become almost entirely digital. Marks are no longer important but it is obviously essential to have a bleed. Set the Bleed in document set up and then select Use Document Bleed Settings.

Output

No Color Conversion - does just what it says – it leaves everything in the document unchanged.

Convert to Destination - Everything in the document is converted to the destination color space, which you choose in the drop down menu.

  • If the destination color space differs from the color space the document
  • was built in, everything in the document is converted – even black type.*
  • (The rendering intent set in the application’s color settings is used for the conversion except when a rendering intent has been explicitly assigned to individual elements. The ability to as-sign ICC profiles and individual render-ing intents in InDesign is only available for non-grayscale, raster files. Vector elements and placed PDFs do not have these controls available.)
  • Placed imagery with an embedded profile that matches the destination profile will remain unchanged.
  • If the document’s working space matches the destination color space, the document will not be converted.

Convert to Destination (Preserve Numbers) - is a very confusing option.

  • Items in a different color mode than the destination color space, for example, RGB elements in a document being converted to a CMYK color space, are converted.
  • Untagged items in the same color mode as the destination color space, untagged CMYK images in a document being converted to a CMYK color space, will be passed through.
  • Elements in the same color mode as the destination color space that have an embedded ICC profile different than the destination profile will be converted.
  • Elements created in InDesign are left unchanged, regardless of the ICC profile assigned to the document.

Profile Inclusion Policy

The options available in the Profile Inclusion Policy change depending on what is selected in the Color Conversion drop-down menu and or the PDF/X standard.

With No Color Conversion selected, there are four options available.

Don’t Include Profiles – The resulting PDF contains no ICC profiles. That’s not a good idea because, if something is missing, the printer has no way of knowing what you intended. Or if he wants to re-separate the file for ink optimization, he won’t have a reference to do this correctly.

Include All Profiles – All elements in the resulting PDF are tagged with an ICC profile. Items that have an ICC profile embedded will keep that ICC profile. Make sure to have profiles included because untagged CMYK elements will have the CMYK Working Space ICC profile embedded. Untagged RGB elements will have the RGB Working Space ICC profile embedded.

Included Tagged Source Profiles – Elements tagged with ICC profiles retain those ICC profiles. Untagged elements remain untagged in the resulting PDF.

Include All RGB and Tagged Source CMYK Profiles – All RGB elements are tagged with ICC profiles. RGB elements with embedded ICC profiles retain those ICC profiles. Untagged RGB elements have the RGB Working Space ICC profile embedded. CMYK elements with embedded ICC profiles retain those ICC profiles. Untagged CMYK elements remain untagged in the resulting PDF. (whereas all RGB will have a profile) Any conversion will assume the output intent. 

When Convert to Destination or Convert to Destination (Preserve Numbers) is selected, there are two options available: Don’t Include Profiles and Include Destination Profile.

In all of these scenarios, grayscale images are untagged in the resulting PDF file regardless of whether they have an embedded ICC profile, or not (not a problem in CMYK because it will print K only but a problem if the file goes to an RGB device.

Convert to Destination (Preserve Numbers) is recommended when a file is prepared with CMYK elements that have been normalized to a single color space. RGB elements still present are converted to the destination color space. CMYK elements that are tagged with a profile that’s different from the destination profile are converted to the destination profile. If they are tagged with a profile that matches the destination profile, or if they’re untagged, they are not converted.

But this is not my preferred choice because of the ambiguities and lack of control in the handling of color in these two options. I choose Color Conversion set to No Color Conversion and that’s not a simple choice either because, unfortunately, Adobe’s implementation of PDF/X-4:2010 sets the Profile Inclusion Policy to Include All RGB and Tagged Source CMYK Profiles. This means that CMYK elements with no embedded ICC profile have no ICC profile in the resulting PDF. Adobe assumes that CMYK files with no embedded ICC profile are set to be in the color space described by the Output Intent profile. But every RIP and every color management tool for PDF has the option to honor Output Intents, or not. If the workflow does not honor the Output Intent during a col-or conversion, then untagged CMYK elements will be handled as dictated by the workflow, not as the file’s creator had intended.

The Simulate Overprint choice is only available when Standard is set to None, Compatibility is set to Acrobat 4, and Color Conversion is set to Convert to Destination or Convert to Destination (Preserve Numbers). When Simulate Overprint is selected, spot colors are converted to process and areas of over-print are broken into individual elements that are colored to create the illusion of overprinting. This choice is not appropriate for offset printing but sometimes right for creating files for on-screen preview, or for certain digital processes that can-not handle in-RIP separations.

PDF/X

PDF/X-4 requires that an Output Intent Profile be present and that renders the other Output Condition identifiers unnecessary. Some PDF/X variants allow for the Output Intent Profile to be an externally referenced ICC profile, and some only require the Out-put Intent Profile to be present if the PDF contains “device-independent” color (Lab or elements tagged with ICC profiles) or if the printing condition is “non-standard”. 

Advanced

Fonts must be embedded to some extent. Subsetting means that only the characters that appear in the PDF are embedded instead of the entire font. To get fonts to embed entirely, set the percentage to 0%. For  TrueType and OpenType fonts to be fully embedded, there’s a preference in InDesign that has to be set. In some cases, PDFs with subsetted fonts will create a font conflict in RIPs.

OPI is only allowed in PDF/X-2:2003 and PD-F/X-5g.

JDF could be useful to those groups with automation but, unless explicitly requested, leave JDF off.

PDFs for print should have no security. Security is forbidden in all PDF/X variants.

In Summary

  • If complying to a PDF/X standard, use PDF/X-4:2010
  • PDF 1.4 or higher to keep transparency
  • Exclude all interactive elements, guides, bookmarks, and hyperlinks
  • Leave Create Tagged PDF off
  • Create layered PDFs only if certain that the print provider is equipped to handle them
  • Minimum resolution of 300 ppi for color and grayscale images, 1200 ppi for monochrome
  • Avoid JPEG, JPEG 2000, and Run Length compression – use only ZIP, LZW, or CCITT
  • If adding marks (crop marks, registration marks, etc.) be sure they will sit completely outside the bleed.
  • Include bleed
  • No Color Conversion to take advantage of superior PDF color management tools
  • Include all ICC profiles
  • Include an Output Intent Profile
  • Embed fonts entirely
  • No OPI
  • No Security

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