17 Facts About Image noise

1.

Image noise is random variation of brightness or color information in images, and is usually an aspect of electronic noise.

FactSnippet No. 978,303
2.

Image noise is an undesirable by-product of image capture that obscures the desired information.

FactSnippet No. 978,304
3.

Original meaning of "Image noise" was "unwanted signal"; unwanted electrical fluctuations in signals received by AM radios caused audible acoustic Image noise .

FactSnippet No. 978,305
4.

Typical model of image noise is Gaussian, additive, independent at each pixel, and independent of the signal intensity, caused primarily by Johnson–Nyquist noise, including that which comes from the reset noise of capacitors .

FactSnippet No. 978,306
5.

Amplifier noise is a major part of the "read noise" of an image sensor, that is, of the constant noise level in dark areas of the image.

FactSnippet No. 978,307
6.

At higher exposures image sensor noise is dominated by shot noise, which is not Gaussian and not independent of signal intensity.

FactSnippet No. 978,308
7.

An image containing salt-and-pepper noise will have dark pixels in bright regions and bright pixels in dark regions.

FactSnippet No. 978,309
8.

Some noise sources show up with a significant orientation in images.

FactSnippet No. 978,310
9.

An image affected by periodic noise will look like a repeating pattern has been added on top of the original image.

FactSnippet No. 978,311
10.

Significant reduction of this Image noise can be achieved by applying notch filters in the frequency domain.

FactSnippet No. 978,312
11.

Size of the image sensor, or effective light collection area per pixel sensor, is the largest determinant of signal levels that determine signal-to-noise ratio and hence apparent noise levels, assuming the aperture area is proportional to sensor area, or that the f-number or focal-plane illuminance is held constant.

FactSnippet No. 978,313
12.

For images at lower signal levels, where read noise is significant, more pixels within a given sensor area will make the image noisier if the per pixel read noise is the same.

FactSnippet No. 978,314
13.

Image noise sensor has individual photosites to collect light from a given area.

FactSnippet No. 978,315
14.

In video and television, Image noise refers to the random dot pattern that is superimposed on the picture as a result of electronic Image noise, the 'snow' that is seen with poor television reception or on VHS tapes.

FactSnippet No. 978,316
15.

Digital video Image noise is sometimes present on videos encoded in MPEG-2 format as a compression artifact.

FactSnippet No. 978,317
16.

High levels of Image noise are almost always undesirable, but there are cases when a certain amount of Image noise is useful, for example to prevent discretization artifacts .

FactSnippet No. 978,318
17.

The increase in Image noise often found when using a higher ISO setting is a result of the amplification of shot Image noise and a lower dynamic range as a result of technical limitations in current technology.

FactSnippet No. 978,319