Image processing

Monochrome black/white image

In electrical engineering and computer science, image processing is any form of signal processing for which the input is an image, such as photographs or frames of video; the output of image processing can be either an image or a set of characteristics or parameters related to the image. Most image-processing techniques involve treating the image as a two-dimensional signal and applying standard signal-processing techniques to it.

Image processing usually refers to digital image processing, but optical and analog image processing are also possible. This article is about general techniques that apply to all of them.

[edit] Typical operations

The red, green, and blue color channels of a photograph by Sergei Mikhailovich Prokudin-Gorskii. The fourth image is a composite.

Among many other image processing operations are:

Geometric transformations such as enlargement, reduction, and rotation
Color corrections such as brightness and contrast adjustments, quantization, or conversion to a different color space
Digital compositing or Optical compositing (combination of two or more images). Used in filmmaking to make a "matte"
Interpolation, demosaicing, and recovery of a full image from a raw image format using a Bayer filter pattern
Image editing (e.g., to increase the quality of a digital image)
Image registration (alignment of two or more images), differencing and morphing
Image segmentation
Extending dynamic range by combining differently exposed images
2-D object recognition with affine invariance

Further information: Imaging

Lectures on Image Processing, by Alan Peters. Vanderbilt University. Updated 28 April 2008.