150 to 200 dpi for newspaper print

300 to 400 dpi for glossy print

600 dpi for high quality commercial print

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Most commercial print companies print on presses that use 4-colour separations - plates that print in four separate colours which when combined on the print material create the final colour blends. This means that images should be CMYK -  which is

Cyan, Magenta, Yellow and Black.

WEB image specifications

Resolution and file formats for web images need to be much smaller than for print images so that they can load quickly.

The three main file formats used are JPG (JPEG), PNG and Gif.

In general, JPGs are used for (rectangular) photos while Gifs are used for cropped images with transparent backgrounds, such as logos, and animations.

Gif images do not use as many colours as JPGs and PNGs so the quality is much lower making them unsuitable for photos.

Instead, PNGs, which can also display images with a variety of transparency effects, can be used for both photos and transparent images.

IMAGE resolution

DPI (dots per inch) refers to the output resolution of a printer or imagesetter. 

PPI (pixels per inch) refers to the input resolution of a photograph or image.

For quality prints, Apple recommends the minimum resolutions shown below. Higher resolutions than these will generally result in higher quality prints at a given size.

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Print size and minimum bitmap resolution size:

• 4 x 6 inches: 600 by 900 pixels

• 5 x 7 inches: 750 by 1050 pixels

• Wallet: 300 by 450 pixels

• 8 x 10 inches: 1200 by 1500 pixels

• 16 x 20 inches: 1600 by 2000 pixels

• 20 x 30 inches: 1600 by 2400 pixels