If you’ve read two previous posts, ‘What is a web-ready PDF?‘ and ‘What is a print-ready PDF?‘, you’ll have a good idea of what they are. This post compares the two, listing the primary differences in the following table, then going into greater depth in the explainer below.
|Low to fair (typically 100 dpi)
|High (typically 300 dpi)
|CMYK and/or spot colour
|Office inkjet/laser printer
|High quality commercial printing
|Not strictly necessary
|Printer’s marks required
|Commercial print environment
|Smallest File Size
|Can be emailed (typically)
|May need a file transfer service
|As is (.pdf)
|As a .zip file
|Advisable in certain circumstances
File size and image quality
Images are a major factor when it comes to PDF file size: the more images there are in a document the larger the file size will be and the higher the quality of those images the larger the file size will be. For print-ready PDF artwork, image quality must match print quality (normally 300 dots per inch) so file size will always be larger than web-ready PDFs which only have to match screen quality (typically 72 to c. 160 pixels per inch).
While there’s no leeway with print-ready PDFs, there is some with web-ready PDFs. Savings can be made if imagery isn’t that important but if imagery is important, say in a product brochure, file size will need to be higher. It’s a trade-off that needs to be considered. Thankfully, with higher broadband speeds, improvements in email file size caps and larger mobile data allowances, file size has become less important than it used to be.
Another difference between web- and print-ready PDFs is colour format: screens use three colours (Red, Green and Blue (RGB)) while print typically uses four (Cyan, Magenta, Yellow and Black (CMYK)), the additional information adding to file size. Colours won’t look the same on screen and in print in a lot of cases so to get the best results and to maintain consistency it’s preferable to stick to the right colour format for the medium.
Web-ready PDFs are suitable only for office or home inkjet or laser printers. They can’t be used for commercial print because neither the quality nor the colour format is correct. Your designer will need to provide you with print-ready PDF artwork prepared to the printer’s or publication’s specifications.
As for using print-ready PDFs for office or home inkjet or laser printing, they will most likely be larger than the original page size and have printers marks (see below). Some software may not be able to print the document minus the extra page area and marks.
Fonts play an important part in graphic design and will have been chosen carefully by your designer to enhance the design. Although it’s not strictly necessary to embed fonts in a web-ready PDF (they’ll be substituted by available local system fonts), if there has been any thought put into design at all then they should be embedded. If design isn’t important and file size is a real issue, not embedding fonts will decrease file size – it’s a bit hit and miss though as some setups may not have suitable substitute fonts available and this may cause layout issues.
Transparency can be used by designers to create an effect such as overlaying colour onto part of an image or overlapping two colours to simulate a third. These effects will work in web-ready PDFs but for print purposes transparency needs to be ‘flattened’: the overlaying colour needs to be combined with that segment of the image and a third colour needs to be created for the area where the two colours overlap.
Printer’s marks and bleed
When, say, a brochure is printed commercially, it’s printed on sheets of paper larger than the finished size. These are then folded, combined in order, bound (e.g., stapled) and trimmed down to the correct final size. The extra paper that ends up on the printer’s floor will have the document’s name and page number detailed and printer’s marks – guides which allow the printer to align each colour accurately as it’s printed and which show where the pages should be folded and trimmed.
These marks are added by the designer to the PDF artwork they prepare for the printer or publication. Bleed will also be added, an extra three millimetres on each side where colour or images extend outside where the page is to be trimmed, just as leeway in case there are any slight errors or issues in folding or trimming. The printer or publication will specify which printer’s marks are to appear and how much bleed is to be added. In some instances, they may specify no printers marks or bleed, e.g., when they are slotting an advert into other content on a page.
So, if you ever come across a PDF on a company’s website which has marks and symbols on the outer edges, you’re most likely looking at print-ready PDF artwork that the website’s owners/maintainers have mistakenly used instead of a web-ready version or have chosen to use rather than request a web-ready version or have the print-ready file converted into the correct format. It happens far more often that you’d think.
Optimisation and InDesign presets
Tweaking file size, image quality and colour format are some of the ways you can optimise PDFs. Adobe InDesign, the industry-standard page layout application for graphic designers, has presets built in to help automate that optimisation. For PDFs destined for the web, ‘Smallest File Size’ is a good option but you can create a custom preset of your own if, for example, you prefer better image quality. For PDF print artwork, one of the most-used industry-standards is ‘PDF/X-1a:2001’ but your printer may specify another.
There is limited scope for adding interactivity to PDFs but you can enrich a reader’s experience by adding links to other pages in the PDF, links to web pages or navigation buttons. Adding links to a table of contents is an easy way to improve a reader’s experience and this can be automated in InDesign when you export a PDF. Interactivity has no function in print-ready PDF artwork.
Sharing and sharing format
If you want to share a PDF to a certain person or group of people, email is the most convenient method as PDF file sizes are generally low. However, print-ready PDF artwork is normally much larger so a file transfer service such as WeTransfer (free if you’re sending files up to 2 GB) may be needed.
Sharing a web-ready PDF as is (.pdf format) is normally fine (unless it’s a very large file) but print-ready PDF artwork should be compressed (.zip format) before sending to protect the file from possible corruption as it passes from server to server.
It’s a good idea to name print-ready PDF artwork so it can be identified easily. You can do this by adding a prefix or suffix to the file name – I always add an ‘X1a-‘ prefix.
Finally, let’s talk about security. For print-ready PDF artwork, you’ll (presumably) be sending the file to a trusted printer or publication and be using a trusted file transfer method so you shouldn’t need to add security unless the content is sensitive. For web-ready PDFs, you may want only certain people to have access to the file or may want to protect the PDF’s content. In those cases, you can either add a password so only those in the know can open the file or add a password to prevent content being copied and/or printed or limit printing to low quality. You may even want to add passwords to restrict both opening and copying/printing. Just be aware though that PDF security is pretty easily broken if you know how to do it.