Resolution and Printing

At last nights meetup we discussed how to know if your digital photo has enough resolution to print on an 11 × 14 inch photo paper, with a simple calculation. Below is a summary of those remarks.

On your computer screen, resolution is measured in terms of pixels per inch (ppi, as folks typically call it). Scanners and printers, on the other hand, refer to resolution as dots per inch (dpi).

The higher the resolution of an image, the smaller the pixels. Small pixels make for smooth, high-quality prints. The lower the resolution, the bigger the pixels, which makes for blocky prints resembling a pile of legos.

Generally speaking, you need a resolution of at least 240 ppi to produce a nice print on most inkjet printers and online printing services. Aiming for a higher resolution in your calculation gets you better prints. Here’s the calculation.

Divide the longest edge of your image dimensions (measured in pixels) by the longest edge of your desired print size (measured in inches). For example, if an image measures 4,200 × 3,300 pixels and you want an 11 × 14 inch print, take the longest edge in pixels and divide it by the longest edge in inches of the target print size: 4,200 pixels ÷ 14 inches = 300 ppi. That’s more than enough resolution to produce a good print; remember, you generally need a minimum of 240 ppi to get a good print.

Here’s how to find your photos dimensions (width x height) in pixels…

A WINDOWS PC:
Select the file you want to use. Right-click on the image and then select “Properties.” A window will appear with the image’s details. Go to the “Details” tab to see the image’s dimensions and resolution in pixels.

ON A MAC:
Checking a photo’s resolution on a Mac is similar to a PC. Select the image you want to use and “Right-click” on it. Click on "Get Info”. The image information window will open. You can find the image dimension and resolution under the “More Info” tab.

If you have any other questions or need help getting your file ready for printing send me or Taryn an email.
Frank’s email: [email protected]
Taryn’s email: [email protected]