Effective resolution
From The Glossary of Digital Photography
(1) A way to measure and compare a film original to a digital original. (2) Scaling an image in a page-layout program. Unless data is added when the image is scaled up, or thrown away when the image is scaled down, the same number of pixels will exist in the larger or smaller image. The resolution of the image has to change proportionally to make up for this phenomenon. This new resolution is known as the effective resolution. See also resolution
