PDFs Explained

What is a PDF?

A PDF is a file saved as a Portable Document Format.

It is a document distribution format that uses Adobe Acrobat Reader (a free downloadable application) to view and print your data.

As the PDF contains all the image and font information within the file it doesn’t require any additional support files to successfully print.

How do I make a PDF?

The method will change depending on your Application and its version, the operating system and its version, also the platform will make a difference.

The two most common methods of making PDF files are ‘print to… pdf’, ‘save as… pdf’ and ‘export to… pdf’.

Please refer to your Application User Guides for your system specifics.

When creating a PDF remember to include both the bleed and registration/crop marks.

What Settings should I use?…

When you create a PDF certain parameters are permanently attached to the file, these settings can cause poor print reproduction of your artwork if set incorrectly.

To avoid this please use the following settings.

… when working at QUARTER size (25%)

Images/Pictures should use the following settings:

Colour sampling should be set at Bicubic Downsampling to 400 pixels per inch for images above 600 pixels per inch with NO COMPRESSION.

Greyscale sampling should be set at Bicubic Downsampling to 400 pixels per inch for images above 600 pixels per inch with NO COMPRESSION.

Monocrome sampling should be set at CCITTGroup4 to 400 pixels per inch for images above 600 pixels per inch with NO COMPRESSION.

Fonts should be set to ‘Embed All Fonts’.

Colour Management Policies should be set to ‘leave colour unchanged’.

… when working at HALF size (50%)

Images/Pictures should use the following settings:

Colour sampling should be set at Bicubic Downsampling to 200 pixels per inch for images above 300 pixels per inch with NO COMPRESSION.

Greyscale sampling should be set at Bicubic Downsampling to 200 pixels per inch for images above 300 pixels per inch with NO COMPRESSION.

Monocrome sampling should be set at CCITTGroup4 to 200 pixels per inch for images above 300 pixels per inch with NO COMPRESSION.

Fonts should be set to ‘Embed All Fonts’.

Colour Management Policies should be set to ‘leave colour unchanged’.

… when working at FULL size (100%)

Images/Pictures should use the following settings:

Colour sampling should be set at Bicubic Downsampling to 100 pixels per inch for images above 150 pixels per inch with NO COMPRESSION.

Greyscale sampling should be set at Bicubic Downsampling to 100 pixels per inch for images above 150 pixels per inch with NO COMPRESSION.

Monocrome sampling should be set at CCITTGroup4 to 100 pixels per inch for images above 150 pixels per inch with NO COMPRESSION.

Fonts should be set to ‘Embed All Fonts’.

Colour Management Policies should be set to ‘leave colour unchanged’.

How can I make my PDF files smaller?

The settings above give us an optimum image resolution for print. To save smaller files set the following:

At QUARTER size Bicubic Downsampling to 400ppi for images above 400ppi.

At HALF size Bicubic Downsampling to 200ppi for images above 200ppi.

At FULL size Bicubic Downsampling to 100ppi for images above 100ppi.

If you need to save even more file space then turn the compression on, see below.

Why shouldn’t I turn image compression on?

The settings given are for optimum print quality. As jpeg is a destructive compression format it will adversely affect the print quality so is not recommended.

However if you are sending the artwork to us via e-mail or an ftp server you may wish to turn compression on to reduce the size of the PDF. As long as the image size is set to its Maximum/Highest value a jpeg compressed file should reproduce well. Always bear in bind that the more you compress the file to save disc space the more you compromise on image quality.

How will jpeg affect the image quality of the PDF?

You may notice a lower quality in jpeged images.

Smooth colour changes, in skyscapes or between the highlight and shadows on fleshtones in portraiture, can be badly effected by low jpeg quality. You will notice that the colour steps through the graduation rather than changing smoothly form one colour to another.
Where there is a rapid change between light and dark areas of an image, around text or logos, you may see ghosting on the edge of the image.

Unfortunately when saving a jpeg you are making permanent changes to the file. This cannot be undone.

Can you edit my PDF files for me?

PDF files can be edited, however the way PDF files deal with graphics and text make it a much more complex procedure to edit than if the file was supplied in its ‘native’ application. Studio time and cost will reflect the additional effort required to edit your PDF files.