1. C021TV-I1-S2

2. ICN : 1. Binary coding
1. Representation of information in the form of bits
2. To store images or sounds
3. Compression
4. Data organization
5. Data bases
Introduction de la semaine 2/2
Présentation du sommaire global de la semaine : apparition progressive des éléments de la liste, puis mise en évidence de la portion concernée par la vidéo.
Mise en évidence = police noire + gras
Nom abrégé de cours - Enseignant

3. Pixels Video games, digital television, virtual reality, …
Which technology for the display?
Pixels (Picture Element)
Composed of 3 colors
Also used for manipulation, printing, etc.

4. Pixels coding Sequence of bits coding each pixel
1 bit per black and white pixel
8 bits for 256 levels of gray
24 bits for colors (8 bits for each component)
How can we know if a sequence of bits corresponds to 24 black and white or only 1 pixel in color?
How can we know if the image is rectangular or square?
A header is needed to specifiy
the pixels coding and the image dimension

5. Bitmap or vector images?
The computer doesn’t know the content of an image
In order to know there is a disc, a pattern recognition
algorithm is required
How to better code such images?
It would be easier to describe the disc
And a lot more succinct!
Good for technical drawings, but not for pictures!
A vector image is a set of mathematical shapes with their colors

6. Sound coding Signal composed of an infinity of intermediate values
We can’t code them all!
Some approximate values
Close enough so that human ear can’t hear the difference
A set of bits for each value
With a header to specify the frequency
Sampling
Nom abrégé de cours - Enseignant

7. "Vector" coding of sound A piece of music is also a score
Easy to code in bits
And instruments characteristics
Type, timbre, …
Similar coding to that of the vector images
Fichiers MIDI
Nom abrégé de cours - Enseignant

8. To remember
Image and sound can be coded by sequences of numbers, of bits
A program enables the computer to interpret this coding to display or to print an image, to play a sound, …
… and to code data during an image scan, a sound recording, …
Between both (storage on the disc, transfer on the Internet, pictures manipulation), the data can remain coded

9. Illustrations
p.2 : Six Fingers © Inria - J.C. Moschetti