Press "Enter" to skip to content

Start Searching the Answers

The Internet has many places to ask questions about anything imaginable and find past answers on almost everything.

How do you classify noise?

Internal noise may be put into the following four categories.

  1. Thermal noise or white noise or Johnson noise.
  2. Shot noise.
  3. Transit time noise.
  4. Miscellaneous internal noise.

Is noise a uniform?

The simplest way to understand noise is to generate it, and the simplest kind to generate is uncorrelated uniform noise (UU noise). “Uniform” means the signal contains random values from a uniform distribution; that is, every value in the range is equally likely.

What is meant by noise in image processing?

Image noise is random variation of brightness or color information in images, and is usually an aspect of electronic noise. It can be produced by the image sensor and circuitry of a scanner or digital camera. Image noise is an undesirable by-product of image capture that obscures the desired information.

What is speckle noise in image processing?

Speckle is a granular interference that inherently exists in and degrades the quality of the active radar, synthetic aperture radar (SAR), medical ultrasound and optical coherence tomography images. It is caused by coherent processing of backscattered signals from multiple distributed targets.

How is speckle formed?

Subjective patterns are caused by the interference of waves from the various scattering regions of a resolution element of the lens. In this region, the response functions of the randomly de-phased waves are added, resulting in the formation of speckle patterns (taken from here).

What is salt and pepper noise in image processing?

Salt-and-pepper noise is a form of noise sometimes seen on images. It is also known as impulse noise. This noise can be caused by sharp and sudden disturbances in the image signal. An effective noise reduction method for this type of noise is a median filter or a morphological filter.

How do you stop a speckle pattern?

Speckle patterns can severely degrade the image quality of laser projection displays, or disturb position measurements with laser pointers. Speckle can often be avoided, e.g. by using a light source with sufficiently large optical bandwidth (short coherence length) such as a superluminescent source.

Why do lasers sparkle?

It is called speckle and it is due to the wave nature of light (interference). Light coming into your eye from a laser does not exhibit speckle. Speckle occurs because the laser light is temporally coherent and is scattered from a random surface.

What is fully developed speckle?

Definitions: we call the situation where the deterministic part remains visible a partially developed speckle pattern. This situation corresponds to t0 ∼ 1, i.e. to a weak diffuser. In contrast, if t0 ≪ 1, such that the deterministic part is suppressed, the speckle pattern is said fully developed.

How do you do speckle tracking echocardiogram?

Steps involved in speckle-tracking echocardiography. A. The endocardial border is manually traced in the end-systolic frame. The automated software creates a region-of-interest that includes the entire myocardial thickness.