What is Gaussian blur in image processing?

Gaussian distribution

In image processing, an image is processed with the help of the function Gaussian distribution to reduce the noise or to simplify details.

The Gaussian distribution (also known as the normal distribution) is a bell-shaped curve with an equal number of observations above and below the mean value. It is necessary to grasp the definitions of "mean," "median," and "mode" to comprehend Gaussian distribution.

  • The "mean" is the computed average of all values.

  • The "median" is the value in the distribution's center (midpoint).

  • The "mode" is the value seen most frequently during the measurement.

The Gaussian image processing
The Gaussian image processing

Gaussian formula

The Gaussian distribution in 1-D is:

Where σ\sigma is the standard deviation of the distribution. We assume that the distribution has a mean of zero at x=0x=0. The distribution is illustrated below:

 The Gaussian distribution with mean 0 and sigma=1
The Gaussian distribution with mean 0 and sigma=1

Gaussian noise

The main causes of Gaussian noise in digital images occur during captures, such as sensor noise induced by inadequate lighting, excessive temperature, or transmission. When smoothing an image, an undesired effect may arise in blurring fine-scaled image borders and features since they correlate to blocked high frequencies. Mean (convolution), median, and Gaussian smoothing are traditional spatial filtering techniques for noise reduction.

The noise reduction using Gaussian noise effect
The noise reduction using Gaussian noise effect

 

Gaussian filter

The Gaussian filter blurs the desired area and cuts the noise with higher frequencies. It works the same as mean filters while representing average weight uniformly. These are linear filters that reduce the noise and blur the edges effectively. They are created as matrices in digital image processing, passing through each pixel of the selected portion.

 

Use cases

A few use cases of Gaussian image processing are:

  • It helps to eliminate noise from blurry images.

  • It is used to reduce noise from the image taken in low light.

  • It can eliminate the bright pixels.

  • It helps to make edges smooth.

  • It is rationally symmetric.

  • We can define the degree of smoothing.

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