Module 1.2: Data Representation

Data Representation

The form in which data is stored, processed, and transmitted.

Bit

The smallest unit of data in a computer; represents either 0 or 1.

Byte

A group of 8 bits.

Binary

A number system that uses only 0 and 1.

American Standard Code for Information Interchange (ASCII)

A character encoding standard used to represent letters, numbers, and symbols. Standard ASCII uses 7 bits, although characters are commonly stored in 8-bit bytes.

Pixel (Picture Element)

The smallest individual element of a digital image.

Bitmap

A collection of encoded pixels that represents an image.

Black-and-White Image

Can use 1 bit per pixel.

Grayscale Image

Commonly uses 8 bits (1 byte) per pixel to represent 256 shades.

Color Image

Commonly uses 3 bytes (24 bits) per pixel.

RGB

A color model that combines red, green, and blue light.

Graphics Interchange Format (GIF)

An image format that supports a palette of up to 256 colors.

Joint Photographic Experts Group (JPEG)

A commonly used method for compressing photographs.

Image Compression

A method of reducing the file size of an image.

ASCII Numbers

Digits are represented as character codes rather than directly as numeric values.

Binary Numbers

Represent numeric values using 0s and 1s.

8-bit Unsigned Integer

Represents values from 0 to 255.

8-bit Signed Integer

Commonly represents values from -128 to 127.

Floating-Point Number

A representation of numbers that can contain fractional parts.

Institute of Electrical and Electronics Engineers.

IEEE

IEEE 754

A standard for floating-point arithmetic established in 1985.

Floating-Point Representation

A method of representing real numbers using a sign, exponent, and significand.

Sign Bit

Determines whether the number is positive or negative.

Biased Exponent

An exponent stored with a fixed bias added.

Mantissa / Significand

Contains the significant binary digits of the number.

Normalized Mantissa

In binary scientific notation, has exactly one nonzero digit (1) before the binary point.

Single Precision

A 32-bit floating-point representation.

Double Precision

A 64-bit floating-point representation.