Depending on what kind of image you wish to submit to a graphic designer, magazine, printer or publisher, please think about your format and quality carefully. Designers working with photographs for print usually prefer 300dpi *.tif or *.psd (Photoshop) images over *jpg. This is because *.jpg is a compressed format. Photographs straight from a digital camera are almost always saved in *.jpg format at 72dpi. This doesn’t mean they aren’t good enough for print, but how then do you judge them? Please read on.

Resolution vs Size

This photo is 300 pixels wide and 200 pixels high (its size). It has a resolution of 300 dpi.
This is equal to 1 inch wide, 0.667 of an inch high and a total of 60,000 dots (or pixels) in the image.

Photo by Andrew Lamb

When creating or editing graphics, it’s important to understand the difference between resolution and size. 

Size in this case refers to the dimensions (height and width) of the image, which you can determine in most image viewing and editing programs. In Windows, you can usually see the height and width of an image when you have it selected.

Resolution is primarily defined by how many 'dots' there are per inch (DPI).  This affects quality, especially for printing.  Magazines and books will usually only print high quality images with 300 dpi.  However, it is very common for designers to convert 72 dpi photos to 300 dpi, when they are large enough (in size) and sharp enough (in quality).  Website images are usually 72 dpi because this makes the file-size (how many bytes or kilobytes the image takes up on your computer hard-drive) smaller and you won't even notice the difference on-screen.