Entry: Computer Science Notes v.4 Monday, August 31, 2009



Huffman Coding
1011111001010
DRAEB


 00  A
   E
   L
   O
   R
   B
   D

**teacher admits he used to be a nerd for stereo systems, used to read magazines about learning which was better with harmonic sounds, etc. lol.

CD's store audio information digitally.

On the surface of the CD are microscopic puts that represent binary digits.

A low intensity laser is pointed a the disk.

--__--__--_ is square wave

Colour
-Perception of the frequencies of light that reach the retinas of our eyes.

Retinas have three types of colour photoreceptor cone cells that correspond to the colors of red, green, and blue.

Colour is expressed as an RGB (red-gree-blue_ value--three numbers that indicate the relative contribution of each of these three primary colours.

AN RGB calue of (255,255,0) maximizes the contribution of red and green, and minimizes the contribution of blue, which results in a bright yellow.

**OMG* They are arguing over the colour for white & black! Wow. lol. Some say O_o;; it's black oh it's white! Get over it...... >_<

Colours are in 8 bits...so you can have 16 million colours.
32bits is 42 billion colours

GIF- 256 colours
JPEG-TIFF - 16 million colours

Colour depth
-the amount of data that is used to represent a colour

HiColour
-1 16 bit colorur depth: five bits used for each number in an rgb value with the extra bit somethings used to represent transparency...

A browser may support only a certain number of specfic colours, creating a palette from which to choose.

Digitizing a picture
-Representing it as a collection of indivudal dots called pixels.

Resolutiuon
-The number of pixels used to repesent a picture.

Raster graphics
-Strogae of data on a pixel-by-pixel basis Bitmap (BMP), GIF, JPEG, and PNG are raster-graphics.

Bitmap format
Contains teh pixel colour valuse of the image from left to right and from top to bottom.

GIF format (indexed color)
Each image is made up of only 256 colours.

JPEG format
Average colour hues over short distances.

PNG format
Like GIF but acheives greater compression with wider range fo colour depths.

Vector graphcis
A format that describes an image in terms of lines and geometric shapes.

A vector graphic is a....

vector graphics can be resized mathematically and changes can be calculated...

Representing Video

Video codec COmpressor/DECompressor
Methods used to shrink the size of a movie to allow it to be played on.

Temproal compression
A technique based on differences btetween consective frames: if most of an image in two frams hasn't changed, why should we waste space to duplicate all of the simmilar information?

Spatial compression
A technique....

**AWESOME we're going over the study guide now. lol Josh helped me so much last night trying to figure a lot of this mess out.

*HECK YES. I'm getting these numbers right with converting hexadecimal to binary!!! :D :D :D :D WOOOO HOOO!!! :D :D :D hahahaha

   0 comments

Leave a Comment:

Name


Homepage (optional)


Comments