Proxy image
From The Glossary of Digital Photography
Also called proxy. (1) A low-resolution image holding the place of a higher resolution image. This substitution is done in some cases when posting video to the Web so that the entire video is not contained in the posting. (2) A technique used in some software programs enabling the photographer to operate on a low-resolution proxy image file until the displayed result is satisfactory; the final displayed result can then be applied to the high-resolution image to create a high-resolution version. This is done to increase the operating speed of the software.
