College Task 2 - Video Fact File continued

Interlacing

http://www.youtube.com/watch?v=XDhHJD0y0-s

Since the interlaced signal contains the two fields of a video frame shot at two different times, it enhances motion perception to the viewer and reduces ‘flicker’ by taking advantage of the ‘persistence of vision’ effect.

The Persistence of vision is the phenomenon of the eye by which an afterimage is thought to persist for approximately one twenty-fifth of a second on the retina.


An ‘afterimage’ or ‘image burn-in’ is an optical illusion that refers to an image continuing to appear in someone's vision after the original image has disappeared. One of the most common afterimages is the bright glow that seems to float before one's eyes after looking into a light source for a few seconds. By closing the eye people can see a better sense of the color in their own aspects.



SD = 720 x 576 PAL (lines in the frame)         

Standard HD = 1280 x 720

Full HD = 1920 x 1080

Pixels = Mean Picture Elements

16.9 = always a rectangle – height + width

CCD = Charged Couple Device – is a chip located inside the camera, when light passes through the camera lens it hits the optical beam (light splitter) inside the CCD which splits the light into RGB (red, green and blue) separately. 

http://www.yteach.co.uk/page.php/resources/view_all?id=p5_LDR_diode_light_LED_bias_colourdepended_resistor_t_page_4&from=search

Charge Coupled Devices (CCDs) were invented in October 19, 1969, by William S. Boyle and George E. Smith at Bell Telephone Laboratories. CCDs are electronic devices, which work by converting light into electronic charge in a silicon chip. This charge is digitized and stored as an image file on a computer.

A CCD is a two-dimensional array of metal-oxide-semiconductor (MOS) capacitors. The charges are stored in the depletion region of the MOS capacitors. Charges are moved in the CCD circuit by manipulating the voltages on the gates of the capacitors so as to allow the charge to spill from one capacitor to the next (thus the name “charge-coupled” device)

A charge detection amplifier detects the presence of the charge packet, providing an output voltage that can be processed. The CCD is a serial device where charge packets are read one at a time.



3 CCD = 3 Charged Couple Devices – Z1 cameras and HD cameras use 3 CCD which instead of having one sensor like the CCD chip, they have three. One for every primary colour, for example 1 sensor is used for the colour blue, one is used for red and the other is used for the colour green. Because these cameras have a 3 CCD inside them, the quality of the pictures/videos have better graphics and less blur.

A three-CCD camera is a camera whose imaging system uses three separate charge-coupled devices, each one taking a separate measurement of the primary colors, red, green, or blue light.
Light coming into the lens is split by a trichroic prism assembly, which directs the appropriate wavelength ranges of light to their respective CCDs. The system is employed by still cameras and professional video cameras such as Z1 cameras.

Compared to cameras with only one CCD, three-CCD cameras generally provides better image quality through resolution and lower noise. By taking separate readings of red, green, and blue values for each pixel, three-CCD cameras achieve much better results than single-CCD cameras.

CMOS = A CMOS sensor (Complementary Metal Oxide Silicon) is a sensor that is normally 10 times less sensitivity then CCD sensor. The human eye can see objects under 1 lux illumination (full moon night).

CCD sensor normally see better or as good as human eye in the range. Lux is 3 to 10 times more sensitive then CMOS sensor.