Page 301 - AI Computer 10

The various key components of information related to digital images are:

• Pixels: Data in computers is stored and transmitted as a
series of ones and zeros called binary digits. To store an
image on a computer, it is broken down into tiny elements
called pixels. A pixel (short for picture element) represents
one dot or one picture cell. it is usually the smallest single
component of a digital image.

• Resolution: An image is made up of a large number of pixels. The term Resolution is used to describe
the crispness and clarity of the images seen on screens of digital devices. It is based on the number of
pixels arranged both ways horizontally and vertically. Image resolution, which expresses the amount
of information in digital pictures, is measured in pixel per inch (PPI) or dot per inch (DPI). If we define
resolution as the total number of pixels, then pixel resolution can be defined with a set of two numbers.
The first number is the width of the picture, or the pixels across columns, and the second number is
height of the picture, or the pixels across its rows. For example, if an image has “a” rows and “b” columns
of pixels, then its resolution can be defined as a × b. Higher is the resolution of an image, better is its
quality.

1x 2x 3x
(10 × 10 px) (20 × 20 px) (30 × 30 px)

• Pixel Value: In case of a digital image, each picture element that represents an image stored inside a
computer has a unique value called Pixel Value which describes the brightness and colour of the picture.
The most common pixel format is the byte image, where this number is stored as an 8-bit integer giving
a range of possible values from 0 to 255. Typically, zero is to be taken as no colour or black, and 255 is
taken to be full colour or white. Let us understand the concept of number of bits and number of patterns
with the help of the table given below:

Number of Bits Different Patterns Calculation Total Number of
Patterns

1 0 1 2^1 2
2 00 01 10 11 2^2 4
3 000 001 010 011 100 101 110 111 2^3 8
4 0000 0001 0010 0011 0100 0101 0110 0111 2^4 16
1000 1001 1010 1011 1110 1111
5 10000 10001 10010 10011 10100 10101 10110 2^5 32
10111 11000 11001 11010 11011 11100 11101
11110 11111

Colour Mode of Images

In general, the term ‘image’ refers to any visual data that can be created or stored in electronic form and can be
described in terms of Grayscale or RGB image.
Grayscale Image

Grayscale image is the one in which the colour of each pixel has a range of shades of gray without apparent colour. The
darkest possible shade is black, which is the total absence of colour or value 0 for the pixel. The lightest possible shade
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