Even some of the best designers go down in a cold sweat when it comes time to send their project to the printer. There are so many checklists, moving parts and details to bear in mind when it comes to getting the project ready for printing. The following lines will cover the technical do’s and dont’s, provide some tips and guidelines and walk you through the process of taking a project from your PC to the printing press.
Planning for colour printing
One of the most usual problems with printing is sending your graphics files that are in the wrong colour space. Here is what you need to keep in mind about colours before you send your file to your printer.
CMYK instead of RGB
Your PC uses a colour space named RGB to produce the colours you can actually see on the screen. A printing press uses a different colour space named CMYK to produce similar colours utilising just 4 colours of ink: magenta, cyan, black and yellow, also know as four colour process. When you send the files to a commercial printer, they need to be in the CYMK colour space.
Plan the quality of the image for professional printing
Low resolution images produce ugly, terrible, hideous printing but most people do not understand the relationship between resolution and quality. You need to plan for your final output at the very beginning of your design, or you will be left with a useless final product.
As a general rule, prints will always look much better with higher resolution images. Let’s elaborate on what we really mean by resolution… image resolution is just how much data is in a digital photo or image, it’s directly related to the number of pixels that are in the image. When you print a photo or image, you need to transfer that data into dots per inch, also called DPI, which determines the quality of a printed piece. Generally, 300 DPI is what you need. Most photos and images on your PC are not at 300 DPI, only 72 DPI. This is because 72 DPI looks good enough on most PCs and the files and documents are much easier for the PC to store and display on the screen. However, make sure you check your photos or images for print quality and make sure that they are 300 DPI or more.
Resampling images for printing
Resizing images can actually lead to problems when printing because the resolution can be unintentionally modified.
When you resample a photo or image, you are actually changing the amount of data in this image. Downsampling removes data and upsampling simply adds more data. When you make an image smaller than the original size, you are downsampling it, whereas when you make it larger you are upsampling.
You should try to avoid upsampling images. Adding data to an image will typically result in a poor printed image.
Image formats that are best for printing
When sending press ready files to your printer you should send the images in the highest quality (not fastest) format possible. Different image formats can compress image data in different ways. PNG and TIFF images usually work best for most print projects. JPG images also work fine at 100% quality, but each time the JPG is saved it is actually recompressed, so the quality will drop quickly if it is saved several times at less than the maximum quality.
Are vector images important when it comes to printing?
Most images are created using a bitmap, which is a series of dots, and are actually called raster images. On the other hand, vector images are not made of dots, they are just a shape plotted by points along a mathematically generated path. Vector images can actually change to any size without losing their quality. Popular vector image formats are AI, EPS and SVG formats. When printing commercially, vector images are important.
- Your text needs to always be in a vector format.
- Line drawings, such as plans, engineer prints or blueprints, need to always be in vector format.
- Logos also work best in a vector format.
Actually anything that is not a photo will work better as a vector.
Some tips for designing images for print
When possible, do as follows:
- Do not upsample the images.
- Ensure the images are at least 300 PPI (or 300-600 DPI).
- Use always vector formats for text, line art as well as logos.