The first portable digital camera weighed 8 pounds and took 23 seconds per picture
In December 1975 a Kodak engineer named Steven Sasson pressed the button on a boxy prototype and waited 23 seconds while it wrote a black-and-white picture of 10,000 pixels onto cassette tape. Kodak never meant to sell it. Within twenty-five years, cameras were being built into mobile phones.
Film photography relied on light-sensitive emulsions developed in chemical baths. A digital camera instead focuses light onto a grid of electronic detectors, each measuring the brightness over one small patch, and an analog-to-digital converter turns those readings into a computer file. Most sensors actually record only intensity, so colour is added by filters and then assembled into values for red, green and blue.
The groundwork took decades. Russell Kirsch produced a digital image on a computer in 1957, a picture of his son. Mariner 4 sent back the first close-up of Mars on 15 July 1965 using a camera system from NASA and JPL, and much early imaging technology came out of the space programme. Bell Labs gave the field its first semiconductor sensor, the charge-coupled device, in 1969. In 1972 Michael Tompsett made the first published colour digital photograph, a portrait of his wife Margaret, which appeared on the cover of Electronics Magazine.
Sasson's machine, built around Fairchild CCD chips from 1973, weighed 3.6 kilograms. Sony produced a consumer camera in 1981, Nikon showed a digital SLR prototype in 1986 and sold the QV-1000C two years later, and the Dycam Model 1 of 1990 became the first widely available model, also sold as the Logitech Fotoman. Prices fell until ordinary buyers could afford them by the late 1990s.
Compression mattered as much as sensors. Nasir Ahmed proposed the discrete cosine transform at Kansas State University in 1972, and it became the core of the JPEG standard introduced in 1992, which shrank files dramatically and became the most used image format. Sharp and Samsung released the first camera phones in 2000, and darkrooms gave way to editing on a personal computer.
Source: Digital photography
