PDF Guidelines

Format

Our preferred format is PDF, output to the PDFx-4 standard. This is an industry standard preset and comes pre-installed on Adobe and Quark applications.
If required, application presets can be found and downloaded via the Ghent
Workgroup.

We can also accept native files from Adobe products and have editing software for PDFs to make changes to finished files, within limits.

If supplying native files, please ‘Package’ or ‘Collect for Output’ including all images and fonts. This will make sure that all necessary elements of your artwork are supplied to us.

Image Resolution

An acceptable resolution for print is 300dpi for products that you can hold in your hand, anything lower than this will start to affect print quality. Images with a higher dpi will not necessarily increase the quality but will substantially increase the file size of the created PDF.

• 300dpi/ppi for greyscale & colour images
• 600-1200dpi/ppi for line art

For formats that are A1, or approximate equivalents, lower resolutions are considered acceptable down to 150dpi, as these are expected to be viewed from a distance.

Colour

It is a good working practice to remove all unwanted colour swatches from your colour pallet before exporting to PDF, this will ensure that only the intended colours will be included on the final PDF.

Anything other than the intended printing colours (CMYK or CMYK+Spot etc) will be converted to CMYK when the file is processed.

Please be aware that the conversion of RGB to CMYK may result in a slight colour shift, this is due to the RGB colour space having a much larger colour gamut. This is worth keeping in mind for colour consistency and corporate colours etc.
Similarly, Pantone Colours are created for a specific pre-mixed ink that can achieve colours that are not possible to create with CMYK ink.

Pantone & Transparencies

Care needs to be taken when using transparency and pantone colour spaces. It is good practice to maintain transparency on Export using the PDF/X-4 settings, as Flattening elements with pantone/spot colours can have poor results. Results can include transparent spot colour areas converting to white when converting to CMYK, or effects like drop shadows creating knock-out white boxes through spot colours. As these are not initially visible on the PDF produced from your file, only becoming apparent after conversion, this can be a major source of confusion as to what is causing the problem. For documents that will be printing in CMYK it is best practice for all pantones/spots to be converted to CMYK before creating the PDF.

It is also good practice to avoid too many transparent effects in the same place, as layering too many together can cause effects to interact poorly, creating knock-out objects through other effects instead of overlaying visually. Objects that require a drop shadow, for example, can be grouped together to apply a single instance to all of them together, rather than multiple individual shadows that would overlay each other.

Another issue that is not initially apparent is that Pantones can be visually overlaid to make them appear darker on screen, which has caught out many designers in the past. This interaction only works on screen, as 100% ink on top of 100% ink will still only produce 100% ink, not a darker colour, when on press. Effects on screen can create visual contrast where none exists when printed.

Output Profile

Output profiles or destination profiles colour manage the output of your pdf, targeting your intended print condition. For example, if your PDFs are to be printed on an UnCoated paper, then an UnCoated profile would be required.

Our recommended profiles are available below:

• Uncoated - PSO_Uncoated_ISO12647_eci.icc
• Coated - ISOcoated_v2_eci.icc

It is advised that, while you are working on your files, you set your software’s profiles to match these. While some print companies recommend Embedding the profiles in your output, we accept both embedded and unembedded profiles.

Please contact us if you would like further advice on colour management and profiles. Our contact details are below.

Fonts

All fonts need to be fully embedded or embedded as a subset. Fonts that are not embedded in a pdf correctly will not maintain the original design and may result in missing characters or letters and overflowed text.

PDF export to the PDF/X-4 standards will automatically embed and subset Fonts and if it cannot, due to the font not being present on your system, it will pop-up a warning that the PDF is not created to the standards.

If supplying native files, all fonts must be supplied with them.

Bleed

A minimum of 3mm bleed is required.

Bleed needs to be applied in the file and then allowed for in the Export stage to work correctly.

Without Bleed, objects that align to the edge of the page may show the paper-white along the trimmed edge, looking unprofessional and poorly finished.

It must be made clear that Bleed must be matching to the object or image that touches the edge of the Trim. It is recommended to allow images to extend over the edge of the page Trim and into the Bleed, while solid colour can simply be expanded. If your image finishes at the exact edge of the page and has no further content, there are methods of expanding the image in software such as Photoshop, or you can simply duplicate the image and mirror it to align it to the edge of the Trim in the Bleed area.

Cutter guides, Spot UV’s and Embossing

Please supply cutter guides, spot UV and embossing as a spot colour clearly named appropriately.

When supplying PDFs having a Preview PDF with the cutter, UV and/or emboss overlaid on the artwork is recommended to ensure correct line-up. Supplying an Artwork PDF of the printed content with a separate PDF for the Cutter, for the UV and for the Emboss, will then ensure that none of the content from one file remains on the others.

If supplying native files, ensuring that the Artwork, the Cutter and any Emboss/UV content are on separate Layers is advised to ensure efficient processing of your files.

Viewing PDFs Accurately

Acrobat Reader, and other PDF viewers, are free to download, but do not have the production tools that a full version of Adobe Acrobat Pro does. These tools can be invaluable for checking for potential problems with your PDFs that may cause delays or additional costs. Below are two examples.

Output Preview - This is a very useful tool for inspecting your finished pdf’s. It can be used to check that your pdf has the correct separations, simulate overprint and display the intended output profile is, i.e ISOcoated_v2_eci.icc
Preflight - Acrobat Pro comes pre-installed with industry standard preflight settings. Preflighting your files is a very good way of checking your pdf’s integrity and that the pdf has been output correctly, however it can also be a little overwhelming in the returned results at first, but once mastered can be very powerful.

By default, Adobe Acrobat Pro has its setting for accurate viewing of Overprint turned off, as having it off produces a better viewing of how a screen would present the information. To set up for Print, the following settings should be adjusted:

Perfect Binding Allowances

When creating products for PUR binding it is advised to leave white space wherever glue is required to attach, and to allow for the way that content will be visually lost because of the glued spine and the glued hinge.

On all perfect bound products, you have what can be called a ‘hinge’. This is a 7mm wide area that runs down the spine edge of the product. The cover is glued to the first and last page of text and not only holds all the pages in place, but gives strength to the binding. Due to this any image that falls inside the 7mm strip of hinge will be lost.

In addition, due to the curve of the pages when opening a book with a glued spine, run-over content can be visually lost in the curve, causing images to appear truncated.

Below are some diagrams that help illustrate this, and how to adjust your artwork to prevent losing important elements of your content.

In the above image you can see how the glue binding hinge will cause the spine to be compressed and how the hinge’s glue area will completely cover a strip of the first and last page of text.

The above image shows how the first page of text would need to be set out to allow for the glued Hinge, note that this would be mirrored on the matching inside front cover page, and would be repeated on the last page of text and inside back cover. Below is how this would appear with actual artwork; the image is split, so that the ‘middle’ of the image is aligned to where the glued hinge will end, allowing the image to appear to be connected across the two pages.

In the regular Text pages, a similar process is applied. This entails moving the contents 3mm outwards and applying a false ‘bleed’ up to the spine edge. This is illustrated in the image below:

Note how the image appears to repeat itself in the centre, which creates the visual effect of the image continuing smoothly when the pages curve into the spine on the finished product.

This technique is effective with images that contain people, sloping lines and graduated tints.

Design Software

We recommend using Adobe-based software for design, such as InDesign, with support from Photoshop and Illustrator for creating the graphics, due to its versatility and its inter-connectivity between the different parts. This comes with the simple, two-step process to create PDFs at PDF/X-4 standard from InDesign.

Quark Express is a known competitor, but will require adjustments to your working methods for creating PDFs as the software processes images and transparency in a different way to Adobe. By default, effects like drop shadows are set to low quality and need to be adjusted to higher quality, otherwise they can cause items below them to become pixelated and lower quality as well.

Microsoft Office products are not considered design software as they do not have the required capability to create PDFs at high quality. Products such as Word and PowerPoint do not produce CMYK or Pantone colours, cannot embed Fonts reliably, and have no reliable control over image quality or resolution.

Free software, such as Canva or Apple Pages, is primarily used for visual design to upload to the Internet. While they have export options for PDF, these settings can fall far short of acceptable quality. Ensuring that Bleed, Crop Marks and high-quality images are preserved when exporting to PDF can be a challenge to designers not familiar with print standards.

Prepress Department
Tel: 01747 856177
Email: prepress@blackmore.co.uk