Printing Lingo: What is Resolution?
In printing, the term Resolution refers to the sharpness and detail of images. Higher resolution means more image detail. Lower resolution means less image detail.
Generally speaking, resolution is the degree to which the eye can distinguish the varying components of an image. On a more technical level, the term resolution refers to a numerical measure of the clarity and sharpness a device, such as a computer monitor or printing press, can create an image. Common measures of resolution include pixels per inch (PPI) and dots per inch (DPI).
Resolution is Often Misunderstood
- What does resolution mean?
- Why can't I use website images for my brochure?
- What is the minimum picture resolution for printing?
Having spent 30+ years in the printing business, I have had my share of questions about resolution and image clarity. In fact, problems with image resolution are some of the most common issues encountered by commercial printers.
Many artwork images we receive to print do not have the high resolution needed for crisp printed output. For instance, images gathered from the web are low resolution and will appear jagged and blurry when printed on a commercial press.
The concept of resolution seems simple, but there is actually a lot of confusion and miscommunication about it…even within the printing industry itself. For example, PPI (pixels per inch) and DPI (dots per inch) are terms which are often used interchangeably. Pixels and dots are similar concepts, but they are not the same thing. Because many seem uncertain about the concept of resolution, I always stress the importance of using an experienced graphics person to create artwork files used for printed materials.
Web images are digital images. Thus, they are created from electronic pixels. Pixels are little individual box-shaped units of color that bump up next to each other to create visually recognizable images such as photos or text. The resolution of web images is generally 72 PPI (pixels per inch), which is regarded as low resolution.
Because lower resolution images contain less detail, they take up less storage space and load quicker on a display screen…which are good traits for website images. However, less detail is a bad trait for printed images. So as a general rule, images from websites do not reproduce well when printed.
A printing press works by applying dots of ink or toner onto paper. The varying colors of these dots and their spatial relationship create the printed images we recognize as photographs or designs. The more dots that are used, the sharper and cleaner the image (up to a point). Most digital and offset printing presses print at a resolution of 300 DPI (dots per inch). 300 DPI is considered high resolution and the minimum DPI for quality printed output.
Since the high resolution artwork files used for printing are created with graphics software, they originally exist in digital (pixel) form. High resolution files are generally large in size because they contain so much detail, but that's okay when it comes to printing. Prior to press output, sophisticated software converts the color information of each pixel into the various dots needed to recreate the artwork onto the printed piece.
Let us know if you have additional questions about image resolution or any other printing concepts. Formax strives to make printing easy for you!
Take care! Keith