Region and Image Properties

Get information about the objects in an image

Image regions, also called objects, connected components, or blobs, have properties such as area, center of mass, orientation, and bounding box. To calculate these properties (and many more), you can use the Image Region Analyzer app or the regionprops function.

You can also measure pixel values of individual pixels, along a path in an image, or aggregated over an entire image.

Apps

Image Region AnalyzerBrowse and filter connected components in an image

Functions

expand all

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

Topics

Region and Object Properties

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.

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.

Pixel and Path Properties

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.

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.

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.

Image Properties

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.

Create Image Histogram

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

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.

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.

Featured Examples