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Region and Image Properties

Get information about the objects in an image

Apps

Image Region AnalyzerBrowse and filter connected components in an image

Functions

regionprops Measure properties of image regions
regionprops3Measure properties of 3-D volumetric image regions
bwareaArea of objects in binary image
bwareafiltExtract objects from binary image by size
bwconncompFind connected components in binary image
bwconvhullGenerate convex hull image from binary image
bwdistDistance transform of binary image
bwdistgeodesicGeodesic distance transform of binary image
bweulerEuler number of binary image
bwperimFind perimeter of objects in binary image
bwpropfiltExtract objects from binary image using properties
bwselectSelect objects in binary image
bwselect3Select objects in binary image
graydistGray-weighted distance transform of grayscale image
imcontourCreate contour plot of image data
imhistHistogram of image data
impixelPixel color values
improfilePixel-value cross-sections along line segments
corr22-D correlation coefficient
mean2Average or mean of matrix elements
std2Standard deviation of matrix elements
bwlabelLabel connected components in 2-D binary image
bwlabelnLabel connected components in binary image
labelmatrixCreate label matrix from bwconncomp structure
bwpackPack binary image
bwunpackUnpack binary image

Examples and How To

Get Pixel Information in Image Viewer App

You can display information about the location and value of individual pixels or small neighborhoods of pixels. This information updates as you move the pointer over the image.

Measure Distance Between Pixels in Image Viewer App

You can measure the length of a line segment drawn between two pixels. You can refine the position of the line segment and make multiple measurements.

Label and Measure Objects in a Binary Image

An object in a binary image is a set of connected pixels with the same value. You can count, label, and isolate objects, and you can compute their area.

Create Image Histogram

This example shows how to create a histogram that shows the distribution of intensities in a grayscale image.

Image Mean, Standard Deviation, and Correlation Coefficient

You can compute standard statistics of all pixels in a 2-D image. The statistics in the toolbox differ from their 1-D counterparts, which operate on each column of an image separately.

Calculate Region Properties Using Image Region Analyzer

This example shows how to find the regions, and how to compute the region properties, of a binary image. You can sort the regions based on the properties.

Concepts

Pixel Values

To determine the values of one or more pixels in an image, you can select points on an image interactively, or you can specify the pixel coordinates in an array.

Image Region Properties

A region in an image has properties such as area, center of mass, orientation, and bounding box.

Distance Transform of a Binary Image

The distance transform of a binary image shows the distance from each pixel to a nonzero pixel. There are different ways to measure the distance between two pixels.

Intensity Profile of Images

The intensity profile of an image is the set of intensity values taken from regularly spaced points along a line or path in the image.

Contour Plot of Image Data

A contour is a path in an image along which intensity values are constant. Contour plots can show the outline of objects in an image or represent a 3-D shape in a 2-D plane.

Correct Nonuniform Background Illumination and Analyze Foreground Objects

This example shows how to enhance an image as a preprocessing step before analysis.

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