Salt-and-pepper noise, also known as impulse noise, is a form of

noise Noise is unwanted sound considered unpleasant, loud or disruptive to hearing. From a physics standpoint, there is no distinction between noise and desired sound, as both are vibrations through a medium, such as air or water. The difference aris ...

sometimes seen on

digital image A digital image is an image composed of picture elements, also known as ''pixels'', each with '' finite'', '' discrete quantities'' of numeric representation for its intensity or gray level that is an output from its two-dimensional functions ...

s. This noise can be caused by sharp and sudden disturbances in the image signal. It presents itself as sparsely occurring white and black

pixel In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a raster image, or the smallest point in an all points addressable display device. In most digital display devices, pixels are the ...

s. An effective

noise reduction Noise reduction is the process of removing noise from a signal. Noise reduction techniques exist for audio and images. Noise reduction algorithms may distort the signal to some degree. Noise rejection is the ability of a circuit to isolate an u ...

method for this type of noise is a

median filter The median filter is a non-linear digital filtering technique, often used to remove noise from an image or signal. Such noise reduction is a typical pre-processing step to improve the results of later processing (for example, edge detection on an ...

or a morphological filter. For reducing either salt noise or pepper noise, but not both, a contraharmonic mean filter can be effective.

References

Noise (graphics) Digital photography Image noise reduction techniques {{Photo-stub

See also

References