This time round, I’d like to offer you some tips about how to produce digital print files, especially with regards to resolution at print. Up to now, we’ve taken a look at the bleed, i.e. what to look out for when deciding what to crop, and at colours and colour modes, where I gave you a run-down how CMYK mode works and how colour spaces are different. In today’s article, I would like to offer you a few guidelines about image resolution, photos, and such like, and explain a bit of the terminology in this area.
Units for print resolution
The print resolution can be described as the amount of detail in an image, i.e. how “sharp” the image is.
The higher the resolution, the clearer the lines and the more detail is visible. One unit to describe this is DPI, an abbreviation for dots per inch, although lots of people talk about dot or pixel density, so along with PPI (pixel per inch) and LPI (lines per inch) DPI is one way of measuring pixel density.
Producing files for print
What should you bear in mind in terms of resolution and format size when producing files for print? Firstly, make sure that all images and photos have been delivered in the resolution required, otherwise they can look pixelated when printed; photos, images, and graphics need at least 250dpi, whether greyscale or colour. Posters need to be produced in 200dpi at the very least, while line art images should be produced with at least 1,200dpi.
Then again, you should always try to pack in the maximum amount of data into the smallest possible file size to keep the amount of data and loading times down. In addition to this, very high resolutions are not necessarily always an advantage inasmuch as files are downscaled when being prepared for print in order to avoid long loading times and possible problems and delays arising from them.
Another important prerequisite for producing printable, error-free digital image files is choosing the right product format. If you are producing an A5 flyer, you’ll need to deliver a file in this size, and as mentioned in the first Print Pilot article, you shouldn’t forget the bleed on this. The format of the printed product will need to be increased by 2mm on each side, making it 4 mm higher and wider; for the example described (A5 at 148x210mm), this would make for a format of 152x214mm. If print files are delivered in another format than the one ordered, they can sometimes be scaled up or down to the right size; but this can lead to the result looking pixelated. The resolution and size of your printed files are therefore directly linked to one another, and if you go by the instructions in our print data guide, there is nothing else that can go wrong (in principle) and your printed end product will look really good.