Chapter 2: Data

bit

bit

is the smallest unit of information stored or manipulated on a computer; it consists of either zero or one.

Digital images

are a collection of pixels. where each pixel consists of binary numbers.

Color

is based on light.

Images

are not often just black and white.

analog signal

exists throughout a continuous interval of time and takes on a continuous range of values.

digital signal

is a sequence of discrete symbols.

Sampling

is recording an analog signal at regular discrete moments and converting them to a digital signal.

Data compression

is useful in computing to save disk space, or to reduce the bandwidth used when sending data (eg, over the Internet).

Compression

is also an important consideration when it comes to backing up and archiving your important files, particularly for uploading over the Internet.

Lossless algorithms

are those that can reconstruct the original message exactly from the compressed message, and lossy algorithms can only reconstruct an appsimation of the original message.

Lossless compression

packs data in such a way that the compressed package can be decompressed, and the data can be pulled out exactly the same as it went in.

Text compression

is another important area for lossless compression.

Lossy compression

is a technique that does not decompress digital data back to 100% of the original.

Images

high image compression loss can be observed in photos when enlarged

Music

there is a difference between an MP3 music and a high-resolution audio file

Video

moving frames of video can handle a greater loss of pixels compared to an image

Data extraction

is the process of obtaining data from a database or software such as a social media website so that it can transport it to another software (such as spreadsheets) designed to support online analytical processing.

graph

is a pictorial representation, a diagram used to represent data.

Graphs and charts

represent data in points, lines, bars, pie charts, and scatter plots.

Picture graphs

use pictures to represent values.

Bar graphs

use either vertical or horizontal bars to represent the values.

Line graphs

use lines to represent the values.

Scatter plots

represent the data with points, and then a best-fit line is drawn through some of the points.