History of digital imaging.

Left: Coolpix 100 (1997), right: Kodak DCS 620 based on Nikon F5 (1999)

Most of us are used to the film introduced in 1889 by Thomas Alva Edison and George Eastman. Capturing images on a film or glass plate with a sensitive layer, that - after a chemical process - delivers an image that can be ‘transmitted’ via a second chemical process on paper, started early 19th century by pioneers like Nièpce, Talbot, Daguerre and many others.

Around 100 years ago some scientists were trying to find another way of capturing images on other media than the abovementioned film.
In 1907 a cathode ray tube (CRT) was patented by the Russian-American engineer Vladimir K. Zworykin (1889-1982). In 1922 he demonstrated his first ‘television system’. Zworykin, working for Westinghouse Laboratories in Pittsburgh (USA), was given patents on his television systems in 1923 and 1938. His CRT had many micro-photo-cells, which deliver a certain charge. This charge can be scanned and saved.
An other Russian engineer, Alexander Matveevich Poniatoff (1892-1980), working for the Shanghai Power Company in China, emigrated to the USA in 1927, where he experimented with the image and sound registration on magnetic tape. In 1944 he founded the well-known AMPEX Company (AMP = his initials + EX = exploration).
On the basis of the high-frequency bias-technic (making qualitative sound registration possible), developed by Walter Bruch (German professor, working for Telefunken AG), Poniatoff developed a better system. Bruch became the ‘father’ of the so called PAL (Phase Alternation Line)* system. For sound registration a tape speed of 9.5, 19 or 38 m/s is enough, but for imaging that speed should be 100 times faster!
In 1951 the first images were recorded by TV-cameras, transformed in electronic pulses and taped on a video tape recorder (VTR). AMPEX improved that system in 1956 by introducing the world’s first rotating magnetic recording head (thus increasing the tape speed).
The TV-tube, initially called Iconoscope later received various names like orthicon, vidicon, saticon, trinicon and many others.

We all know the American film actor and singer Bing Crosby. His live performance in a military camp on January 13, 1951 was recorded on a VTR and was broadcasted on TV one week later. Recording and broadcasting live and/or later became such a success, that Crosby set up his own Bing Crosby Laboratories, financing a research team, headed by John Mullin. By the development of the computer, where information is converted by a binary system, information supplied by scanned micro-photo-cells or charged coupled devices (CCD) can be converted in digital impulses. Around 1980 the cathode ray tube (CRT), used in TV-cameras, was replaced by a CCD-sensor. Sony and Matsushita are the frontrunner's here.

The NASA played an important role in the development of digital imaging, too.

Texas Instruments patented in 1972 a ‘filmless’ camera and in August 1981 Sony introduced the very first digital photo-camera - called ‘still camera’ - the Sony Mavica. Images were recorded/captured on a CCD, transmitted to a diskette, which could be read in a CD-ROM player, connected to a TV-set or printer. Many among us think this wasn’t the first digital photo-camera but a video-camera that could make ‘stills’. Nevertheless Sony was the first with a serial produced digital camera.
Film giant Kodak came with its first mega-pixel sensor (1.4 Mp) in 1986, followed by many hard and software products. Kodak - BTW - claims to have made the very first digital image in 1975 with a camera system, developed by its engineer Steven Sasson. That particular camera was weighting in at 4 kilo and used 16 AA-batteries! Kodak introduced a ‘digital camera system’ (DCS) on the basis of the Nikon F3, offering a sensor with 1.3 Mp. Later Kodak produced many digital cameras on the basis of various Canon and Nikon cameras. But other manufacturers became interested in digital imaging as well. Apple introduced its QuickTake 100, Casio its QV-11 and - of course - Sony its Cybershot.

Sensor types.

A CCD is a sensor type with a small plate on which millions of light sensitive cells (aka photo-diodes or semi-conductors or pixels) are placed, that issue a charge as soon as they catch light. As all cells are impervious to colours, on each cell a Bayer filter (named after the Kodak engineer Bryce Bayer) for each main colour (red, green and blue) is placed. The charge of a cell is passed to the neighbouring cell and read at the sensor’s edge and converted to digital impulses.

A CMOS-sensor (Complementary Metal-Oxide Semi-conductor) has next to each cell an extra circuit converting the light energy into a charge, which is converted into digital impulses.

Both sensors are used in Nikon digital cameras and are delivering images of an outstanding quality.

Nikon introduced with the Nikon D2H its own sensor, which we have not seen later again (for whatever reason!). This JFET-LBCAST (Junction Field Effect Transistor - Lateral Buried Charge Accumulator and Sensoring Transistor) has cells that are read individually.

Other manufacturers are producing their own sensor types, like Sigma (Foveon sensor) and Fuji (Super-CCD).

* PAL TV-system is used in Europe mainly, although the French - of course! - invented and applying their own system, which is used in some East-European and African countries as well.: SECAM = Séquentiel Couleur à Mémoire). The Americans developed a system according to the National Television Standards Committee (NTSC), in Europe nicknamed: ‘Never The Same Colour’. PAL - on the other hand - is nicknamed by the Americans as ‘Picture Always Lousy’. SECAM is scoffed at as ‘System Essentially Contrary to American Method’.
A motion picture can be best seen at projection speeds of 24 fps and higher. PAL has a projection speed of 625 image lines by 25 fps and NTSC 525 image lines by 30 fps. SECAM has the same projection technics as PAL, although colour projection is different. SECAM tapes, played on a PAL-recorder and visa versa pictures are in black-and-white only. PAL and SECAM tapes cannot be played on a NTSC-recorder and visa versa. However - most video-recorders sold in Europe do have built-in converters.