Design Basics: Screen Resolution vs Print Resolution

Lo-res Left, Hi-res Right

Confusion Over Resolution

Clients often ask, “Is this image large enough?” or “Why doesn’t the image print as clearly as I see it on my screen?” Though there tends to be confusion over the meaning of pixels, resolution, and dots per inch (dpi). Pixels and image resolution relate when it comes to screens/monitors as well as the images being displayed on them. Thus, they are strictly digital, whereas dpi relates solely to printed materials, or print resolution. Image resolution tends to be measured as pixels per inch or ppi. There is a maximum number of pixels any given screen can display, depending on its specification (screen resolution). Though there are programs that allow you to adjust the size of images and resample them, for example, Photoshop. However, when displaying images, the screen or browser is only concerned with the actual pixel dimensions of the image not the ppi. In the example below you can see clearly that the ppi has no effect on the display of the images, they all look the same.

Determining Print Resolution

Printing is where the PPI/DPI value comes into play. There is a simple mathematical computation that you can make which will allow you to ascertain the maximum size at which you can print an image. As an aside, the value that printers prefer regarding PPI/DPI is 300. To determine print resolution simply divide the width by the resolution(ppi) and the length by the resolution(ppi) this will give you the print dimensions of your image. For example, we have an image that is 6.4” x 2.8” with a ppi of 300. This would allow us a maximum print size of 46.88” x 107.14”. However, if we had the same dimension image at 72 ppi our maximum print size is only 11.25” x 25.71”. On a related note, I want to mention bleed. A bleed is where you have the image larger than the finished size which allows for the image to be trimmed down without a white border. For example, if you want an 8” x 10” finished size you would generally make your file 1/8” larger on each side so your bleed size would be 8.25” x 10.25”. Why is a bleed optimal for best results? Plainly speaking if there is a border around the image it won’t necessarily be equal around the finished product after the trimming to finished size. Also, it makes for a cleaner design. While bleed doesn’t necessarily tie in with resolution it is still an important thing to consider when preparing your designs for print.

Resolution Solution

As a recap: Image resolution is the way the image is displayed on a screen. PPI has no effect on the display of the image. However, PPI does affect the file size as the dimensions tend to be larger. While resampling smaller images can allow larger prints it tends to lose some clarity or sharpness in the details, although technology is changing and they are becoming better at resampling all the time. PPI/DPI only matter when printing is concerned. Recall the formula for determining print size PPI ÷ length, PPI ÷ width. Be sure to send your printer images of 300 PPI for best quality. Also, don’t forget to add bleeds to your designs for the seamless look and to keep them clean. Our hope is that you now have a clearer understanding about what resolution is and how to navigate it when it comes to screens and prints.

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