Raster Image - Feature (Image Properties)

About

A feature is property of an image.

Articles Related

Example

intensity,
color,
texture.

Scope

Global

For the whole image

Local

For a set of pixel.

Local features provide a limited set of well localized and individually identifiable anchor points. Their location must be determined accurately and in a stable manner over time. They can be used as a robust image representation, that allows to recognize objects or scenes without the need for segmentation. Features need to be described, such that they can be identified and matched.

Local features are covariant.
The descriptors derived from them, on the other hand, are usually invariant, due to a normalization step.

Example:

points (interest point)
region
edge segment
small image patches
corner,
blob

Usage

edges detected in aerial images often correspond to roads;
blob detection can be used to identify impurities in some inspection task;
matching or tracking applications,
camera calibration or 3D reconstruction.
image alignment or mosaicing
object recognition
scene classification,
texture analysis,

Detection

To localize features in images, a local neighborhood of pixels needs to be analyzed
spatial extent: the local neighborhood of pixels