For images printed on good quality paper using an offset press, the general rule is that the image resolution needs to be twice the screen ruling used to print the job. Magazines are typically printed using a 150 or 175 lpi screen ruling. This means images need to be 300 dpi.

Please note that a slightly lower resolution such as 220 to 250 dpi is also perfectly acceptable for most people. For high quality jobs such as art books or for images containing critical patterns such as brick walls or clothing with a pattern in it, a higher resolution is sometimes recommended by the printer. Typically 400 dpi is used for such images.

Newspapers are printed at a higher speed on lower quality paper. This means the resolution requirements are not as high as those for magazines.

Typically a resolution of 200 to 250 dpi is considered sufficient. For line art images, 400 to 600 dpi is recommended.

The larger a picture gets printed, the lower its resolution needs to be. The main reason behind this is that the viewing distance also increases.

For large billboards, 30 dpi is often sufficient – which means that a lot of digital cameras are perfectly capable of generating such files.