A pixel (or pel or picture element) may refer to either the smallest discrete element of the physical display or to the smallest element of the image. Voxel is its 3-dimensional equivalent, as employed in CT and other cross-sectional imaging modalities.
History and etymology
The history of the term pixel is long and complex 3. A pixel is a portmanteau of the shortening of the words 'picture' and 'element'. Picture element as a phrase is first seen in a publication in 1927, one of the first articles about the new technology of television 1!
The use of the word 'pix' as a shortening of picture was already in common usage in 1934, when it is found in Variety, the American film industry magazine 3.
Pixel does not appear in print until 1965, in a paper presented at SPIE (Society of Photo-Optical Instrumentation Engineers) by an engineer working at the Jet Propulsion Laboratory (JPL) called Fred Crockett Billingsley (1921-2002) 2,3. Its very first use in speech is not known, but it was clearly already being used in engineering circles in 1964 3.
The term 'pel' (sometimes PEL) as a contraction of 'picture element' has also been used previously as another synonym for pixel but outside specialized fields has never caught on and it is not used in medical imaging.
The term pixel was commonly appearing in the radiology literature in the 1970s with the advent of CT.
- 1. Dinsdale A. Television demonstration in America: A successful public demonstration of television between Washington and New York. Wireless World and Radio Review. 1927; XX: 680–686.
- 2. Billingsley FC. Digital video processing at JPL in Eugene B. Turner (ed.) Electronic Imaging Techniques I, Proceedings of SPIE, 1965;3: XV-1–19. https://doi.org/10.1117/12.970964
- 3. Lyon RF. A brief history of 'pixel'. Paper EI 6069-1. Digital Photography II — Invited Paper. IS&T/SPIE Symposium on Electronic Imaging. 15–19 January 2006, San Jose, California, USA. doi: 10.1117/12.644941; https://doi.org/10.1117/12.644941