Chapter 2. Concepts

We'll start by introducing a few concepts which should make it easier to understand how Emacs Photo Database works. As we attempt to store the information required by a photographer using a real darkroom (instead of a digital camera and a computer) to process the images, Emacs Photo Database models the stages of image creation accordingly. Each database item has a unique name. It is prudent to stick to a systematic naming scheme for all database items, as this makes it so much simpler to keep track of your items.


For 35mm or roll film, a "film" is trivially just that: a roll which contains a set of negatives. For sheet film, a "film" is a batch of sheets which are processed together in the same tray, drum, or tank.


A negative is one piece of film which you expose to record an image. Each film may contain several negatives, and of course you can make an unlimited number of prints from each negative.


A print is either a single exposed sheet of photographic paper made from a particular negative, or (more conveniently) a set of conditions to reproducibly create such a print.