
Our brain seeks to make the
universe orderly. For example, a still picture can be
sliced and diced into an array of small dots or pixels.
If you stand back, our brain reassembles the dots as a
coherent image of the original picture. A photo in a
daily newspaper illustrates this effect.
Divide a moving scene into a sequence of still images. Then
repeat the image sequence at a fast rate. If fast
enough, our brain perceives the 'stills' as a moving motion
picture. This process is employed to construct
animation, movies, and television.
Our mind's eye also recognizes a rainbow of color from a mix
of only three-primary-colors of light, red, green, and
blue.
Mixing the three colors allows television engineers to produce
a great range of visible-color.
Handbook Note: A photodiode converts light to electrical
current.
The TV Camera
A TV camera divides a moving image into a sequence of still
picture frames. Similar to a newspaper photo, each still
frame divides into pixel dots of light. The sequence of
images begins as a TV camera lens focuses its light on the
photo-diode array of a charged-coupled-devise or CCD.
CCD photo-diodes convert light to electrical current.
Each sub-pixel or photo-site of the CCD array filter passes
its assigned color -- red, green, or blue.
The CCD electronically scans the array at 60
*
frames per second -- left to right, line by line, photo-diode
by photo-diode, top to bottom. Each photo-diode of
streaming electric current is a modulating analog of the
original red, green, or blue light. The modulating
streams ultimately convert back into illuminated pixel arrays
of the original image sequence of still frames on the
television screen.
*Handbook Note:
The C.I.E. Rec 2020 UltraHDTV
specification added the frame rate option of 120 frames per
second.