Types of digital images

Jun 1 • Notes • 5130 Views • 2 Comments on Types of digital images

Types of digital image


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


Generally we consider four type of images:

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

File:Neighborhood watch bw.png

                                            Figure.1. Example  of  binary 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

Types of digital image

Figure.2. example of gray-scale image


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


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 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.


  1. What is digital image??


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

2. What are the types of digital image??


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??


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??


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


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2 Responses to Types of digital images

  1. Ritika says:

    Digital images have flooded the market since 90s. Since then, new advancements are going on!

  2. Sanjay Kumar says:

    this article help us a lot in understanding the digital image and others things about digital image. so checkout the above article . It will really helpful you………………….

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