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 Analyzer

Browse and filter connected components in image

Functions

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Measure Properties of Image Regions

`regionprops`	Measure properties of image regions
`regionprops3`	Measure properties of 3-D volumetric image regions
`bwarea`	Area of objects in binary image
`bwconvhull`	Generate convex hull image from binary image
`bweuler`	Euler number of binary image
`bwferet`	Measure Feret properties
`bwperim`	Find perimeter of objects in binary image

Measure Properties of Pixels and Paths

`impixel`	Pixel color values
`improfile`	Pixel-value cross-sections along line segments
`imcontour`	Create contour plot of image data

Measure Properties of Images

`bwdist`	Distance transform of binary image
`bwdistgeodesic`	Geodesic distance transform of binary image
`graydist`	Gray-weighted distance transform of grayscale image
`imhist`	Histogram of image data
`mean2`	Average or mean of matrix elements
`std2`	Standard deviation of matrix elements
`corr2`	2-D correlation coefficient

Find, Select, and Label Objects in Binary Images

`bwconncomp`	Find and count connected components in binary image
`bwareaopen`	Remove small objects from binary image
`bwareafilt`	Extract objects from binary image by size
`bwpropfilt`	Extract objects from binary image using properties
`bwselect`	Select objects in binary image
`bwselect3`	Select objects in binary volume
`bwlabel`	Label connected components in 2-D binary image
`bwlabeln`	Label connected components in binary image
`cc2bw`	Convert connected components to binary image (Since R2024a)
`labelmatrix`	Create label matrix from objects in connected components
`label2rgb`	Convert label matrix into RGB image
`poly2label`	Create label matrix from set of ROIs (Since R2020b)
`poly2mask`	Convert region of interest (ROI) polygon to region mask

Topics

Region and Object Properties

Label and Measure Connected Components 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 measure object properties such as area.
Calculate Properties of Image Regions Using Image Region Analyzer
Calculate the properties of regions in binary images and identify the region with the largest area by using the Image Region Analyzer app.

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
Display information about the location and value of individual pixels or view neighborhoods of pixel values.
Measure Distances and Areas Using Image Viewer App
Measure the length of a line segment drawn between two pixels or the area within a drawn polygon.
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
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.
Create Contour Plot of Grayscale Image
Create a contour plot showing paths of constant intensity in a grayscale image.

Featured Examples

Measuring Regions in Grayscale Images

Measure properties of objects in a grayscale image, such as the centroid locations and standard deviation of pixel values.

Open Live Script

Filter Images on Properties Using Image Region Analyzer App

Create a new binary image that consists of regions whose properties, such as area, are within a specified range.

Open Live Script

Find the Length of a Pendulum in Motion

Segment a video of a swinging pendulum and find the center of the pendulum to calculate its length.

Open Script

Correct Nonuniform Illumination and Analyze Foreground Objects

Perform image preprocessing such as morphological opening and contrast adjustment. Then, create a binary image and compute statistics of image foreground objects.

Open Live Script

Detect and Count Cell Nuclei in Whole Slide Images

Use color thresholding and region property analysis, while working with small blocks of image data, to detect nuclei in WSIs.

Open Live Script

Image Retrieval Using Customized Bag of Features

Create a Content Based Image Retrieval (CBIR) system using a customized bag-of-features workflow.

(Computer Vision Toolbox)