File format for the exchange of resolution-independent, pixel-based (bitmapped) images, intended for very high quality moving image content for theatrical distribution; DPX masters provide the input for film recording (digital images back to film for projection) or D-Cinema digital projection systems.
Most modern pianos have a row of 88 black and white keys (52 white keys for the notes of the C Major scale (the notes C, D, E, F, G, A and B) and 36 shorter black keys, which are raised above the white keys, and set further back on the keyboard.
In the Western tradition of music, there are basically twelve keys, corresponding to the twelve notes of the chromatic scale on a keyboard instrument (ie C, C#, D, D#...etc all the way up to C again). But as these can be either major or minor, we end up with a total of 12 major + 12 minor = 24 possible keys.