Text encryption
Written, written, signed information. Oprd. the processor sequence produces the result. Letter (required value), decimal (0-9), binary code (001-111). ASCII table (ASCII – American standard code for information interchange, 1963)
Windows-1251 table:
0-32 : line feed, space input operations
33-127: international (Latin) and mat. operations
128-255: national, Russian alphabet or other languages
Table Unicode
2bit = 1 symbol
Windows, MS-DOS, COY-8,ISO,Mac = N = 2^8 = 256
Unicode N = 2^16 = 65536
Graphic encryption
Discrete graph = an image composed in a way that is visible or understandable to us. Analog graph = a finished image with no visible composition or creation methods.
Spatial sampling – breaking a picture into pixels or parts. The spatial resolution of a monitor is the number of pixels that make up the image on its screen. Color rendering systems RGB , CMYK (cyan, magenta, yellow, key=black), Pantone
Pixel – point on the screen (3 RGB light diodes)
Dead pixel – one of the diodes may not work and as a result the dot on the screen will be black or blank Dot color coding
2^i = N
N — number of color
i — color depth, binary code length, use. to encode pixel color
i = 8, N=256 | i=16, N=65356 | i=24, N=16777216
Sound encryption
An example of a finished digitized sound by amplitude
Digitized sound – divided into sectors of sound level (sampling frequency)
Higher sampling rate results in higher quality sound
2^b = b = number of bits in sound
2^3 = 8 = 8 — sound value
H — number of sampling frequencies (measurements) per second (Hz can be used as a unit of measurement) 1hz= 1s^-1
I = 22050 hz *25 s *16 bit = 8820000 bit = 1102500 b = 1077 kb = 1,05 mb
22050 hz = sound frequency
25 s = time interval
16 bit = sound depth
Video encryption
1 pixel = has information about brightness and color, removing color = black and white screen, removing brightness = no picture (black screen). Saving memory – lowering the resolution of color channels.
j — кол-во пикселей по горизонтали исп в шаблоне
а — кол-во значении цветовой составляющей в 1-м ряду
b — кол-во значении цветовой составляющей в 2-м ряду
если 2=1 то пишут 0
4:4:4 = 4 пикселя по ширине и 2 по высоте, кол-во данных о яркости = кол-во данных о цветности
4:4:4 — RGB
4:2:2 — видеокамеры проф. форматов xdCAM, xdPRO
4:2:0 — JPEG, кодек для конечного просмотра/плохо работает с спец. эффектами
внутрикадровое сжатие (intraframe) — DV (digital video) = старый кодек, удобность редактирования (несколько картинок jpeg синхр с звуком и таймкодом, имеет развертку)
1ч = 13 Gb (DV)
фильм = 26 Gb (DV)
DVD = 4-8 Gb
