Posters are a great way to show off your business or idea, message or thoughts. You want the best image that shows off your message in the best way possible.
In order to get the best out of your posters try and follow the basic rules outlined below:
Add a 3mm bleed around your image in order to cope with slight differences in the cutting technology during production
Make sure the resolution of your image is at least 300dpi (dots per inch). The larger the poster the more DPI you should strive to have. A poor image/photograph will only look worse as they get larger.
Use CMYK as you colour mode where possible - avoid RGB if you can. Here’s why:
CMYK is short for Cyan, Magenta, Yellow, and Black (K is a left over from original ink printing days), RGB is Red, Green, and Blue. RGB is the colour standard on computers and therefore there are millions of colour combinations available for your screen, whereas with CMYK there are only a few, hence why you may have had digital photos printed in the past that look significantly different to what you expected when viewing it on a computer. RGB images can be printed successfully but expect to see differences when printed.
Save your files in uneditable, print-ready file formats (PDF (1.4 or higher), TIFF, EPS, JPG). Deliver your files in one layer: the background layer.
Make sure you convert fonts to outlines or embed all the fonts when saving it to PDF.
Fonts should be at least 6 pt.
If you want full and deep blacks, use Rich Black (C:63% M:52% Y:51% K:100%) for larger areas and text. Do not use this value for text smaller than 15pt or plain text. This option is only usable for full colour printing. For designing black smaller texts use 100% black.
When setting up colour only force colour images to CMYK with a 260% ink limit (for example, in Photoshop > Convert Color Profile > Photoshop 5 Default CMYK). For best results make sure the ink coverage isn't higher than 300%.
To prevent colour wash or fade out, lines should be at least 0.25pt, while negative lines should be at least 0.5pt.
Make sure no elements in your artwork are set on overprint, unless you want this effect in your results. The degree of transparency in printing depends on the ink, paper, and printing method used.