Types of digital images

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Types of digital image

DIGITAL IMAGES:

Numeric representation of a two dimensional image is known as digital image. It may be vector or raster type.

TYPES OF DIGITAL IMAGE:

Generally we consider four type of images:

1. Binary images
2. Gray-scale images
3. Color images
4. Multispectral images

BINARY IMAGES:

Binary images can take one two value 0 and 1 or typically black and white. Binary images takes only 1 binary digit to represent each pixel so it is also known as 1-bit image. e.g. – optical character recognition (OCR).

Through threshold operation from the gray-scale images binary images are created. In threshold operation , every pixel above the threshold value is turned white (1), and those below the threshold are  turned black (0).

                                            Figure.1. Example  of  binary image

GRAY-SCALE IMAGE:

These images are also known as monochrome or one-color images. Gray-level images only contain gray level information they do not contain any color information. Available number of different gray levels is determined by the number of bits used for each pixel.

For example: for 256 different gray level gray scale image should contain 8bits/pixel data.

12 or 16bits/pixel data are used for the medical imaging and astronomy.

Types of digital image

Figure.2. example of gray-scale image

COLOR IMAGES:

Color images are created as three-band monochrome image data, in which each band of image data corresponds to a different color. In each spectral band there is a gray-level information which is the actual information stored in the digital image.

Color images are also known as the RGB image because color images are represented as the red, green, and blue. Color images would have 24-bits/pixels by using 8-bit monochrome standard as a model and 8-bits for each of the three color band (red, green and blue).

Figure.3. example of color image

MULTISPECTRAL IMAGES:

This type of images contain the information outside the normal human perceptual range. Information represented is not directly visible by human system so, these are not images in the usual sense. However by mapping the different spectral band to RGB components the information is represented in visual form. Multispectral images include the ultraviolet, infrared, X-ray, radar data and acoustic.

IMAGE TRANSFORMATION:

DEFINATION:

Image transformation is a function that produces an image as output and takes an image as input. The input and output image may have different interpretation or may appear entirely different, depending on the transform chosen.

Example of image transformation are principal component analysis, fourier transform and various spatial filter.

figure.4. example of image transformation.

From the two or more sources image transformation generates the new image which highlights the particular feature of interest, better than the original input images.

QUESTION & ANSWER

1. What is digital image??

ANSWER

Numerical representation of two dimensional image  is called as digital image.

2. What are the types of digital image??

ANSWER

There are four types of digital image:

1. Binary image
2. Gray-scale image
3. Color image
4. Multispectral image

3. Color images are known as RGB images. WHY??

ANSWER

Color images are known as the RGB images because images are represented as the red, green and blue. Color image require 24bits/pixel image data 8-bits for each color band (red, green and blue).

4. What are the example of image transformation??

ANSWER

Example of image transformation are principal component analysis, fourier transform and various spatial filter.

IES SYLLABUS:

IES Syllabus for Electronics and Telecommunication

GATE SYLLABUS:

GATE  Syllabus for Electronics and Communication

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