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IMAGE ENHANCEMENT TECHNIQUES

By Admin on

WHAT IS IMAGE ENHANCEMENT?

            Image Enhancement is the process of manipulating an image so that the result is more suitable than the original for a specific application.The aim of image enhancement is to improve the interpretability or perception of information in images for human viewers, or to provide `better' input for other automated image processing techniques.

Image enhancement techniques can be divided into two broad categories:

  • Spatial Domain
  • Frequency Domain

Spatial Domain Transformation are

  • Point operations
  •  Mask Operations

Point Operation:

  • Operation deals with pixel intensity values individually.
  • The intensity values are altered using particular transformation techniques as per the requirement.
  • The transformed output pixel value does not depend on any of the neighbouring pixel value of the input image.

Examples:

  1. Image Negative.
  2.  Contrast Stretching.
  3.  Thresholding.
  4.  Brightness Enhancement.
  5.  Log Transformation.
  6.  Power Law Transformation.

Mask Operation:

  • Mask is a small matrix useful for blurring, sharpening, edge-detection and more.
  • New image is generated by multiplying the input image with the mask matrix.
  • The output pixel values thus depend on the neighbouring input pixel values.
  • The mask may be of any dimension 3X3 4X4 ….

Image Negative

    Negative images are useful for enhancing white or grey detail embedded in dark regions of an image.

The negative of an image with gray levels in the range [0,L-1] is obtained by using the expression

                       s = L -1 - r

                       L-1 = Maximum pixel value .

                      r = Pixel value of an image.

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