Frederic Crockett Billingsley (23 July 1921–31 May 2002) was an American engineer who developed techniques for digital image processing while at JPL working on U.S space probes to the moon, Mars, and other planets. Billingsley is
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| Photo of Fred C. Billingsley, cropped from a photo that appeared in both of his 1965 SPIE papers |
generally credited with being the first to use the term pixel in a publication. His work at JPL resulted in VICAR, a set of programs and procedures to enable the acquisition, processing, and handling of the digital image data produced by JPL’s planetary exploration program. An overview of VICAR is available in JPL's papers here.
Billingsley published two papers in 1965 using the word pixel and may have been the first to publish that neologism for picture (Pix) element (el). Research Scientist Richard Lyon reported on his research and his search for the first use of the term pixel and all that led to Billingsley. Lyon did exhaustive research for over three years tracking down the first instances and use of the term pixel. He published a paper in SPIE and gave a great talk on it at the Computer History Museum.
The term pixel is important to understand because it gets used to describe a display’s resolution and is also used to describe a photosensor used in a camera—the definition is different for each. A pixel in a display consists of three elements: red, blue, and green. A pixel in a camera sensor is one color, so it’s three pixels per element. According to Lyon, “Resolution is something you should measure, pixels are something you count.”
It’s really quite surprising how various industries such as photography, computers, image processing, cinema, remote sensing, and microscopy struggled to try to come up with a meaningful, defendable, single-word description for what we now casually call a pixel. In microscopy, a pixel is measured in nanometers, and in remote sensing, a pixel might be a meter. The distinction mentioned above between cameras and displays wasn’t easily or smoothly resolved either. Many display manufacturers, going back to CRT days, argued (as do the camera senor people today) that each bit of color, such as the triad in a color CRT, represented a unit of independent information and therefore was a bit or an element. And when the color range or spectrum of a monitor is described, it is done with color bits, e.g., 2²&sup4; = 16.3 million colors. If such a convention had been followed, the screen you’re looking at would not be 4K or 8.3 Mpixels; it would be 4k – 24.8 Mpixels.
Another aspect of pixel resolution is the quantum of adjacent pixels which give such sharp distinctions when compared to film. And as a result, even though film has a much broader color range, a digital display seems sharper. So far, no one has been able to make a simple conversion algorithm between film and digital.
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So even though we have a workable name, the nuances of what a pixel is, and isn’t, will carry on. That’s why this industry is so much fun.
| May the pixels be with you. |
For more stories on the first pixel, get a copy of The History of Visual Magic in Computers. And if you already have a copy, look at page 290 and you will discover Hermann Vogel, photochemist and photographer who helped invent modern photographer and discovered the correlation between light waves and color.