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Object Analysis

Detect edges, circles and lines; trace boundaries; perform quadtree decomposition

Functions

bwboundaries Trace region boundaries in binary image
bwtraceboundary Trace object in binary image
visboundaries Plot region boundaries
edge Find edges in intensity image
imfindcircles Find circles using circular Hough transform
viscircles Create circle
imgradient Gradient magnitude and direction of an image
imgradientxy Directional gradients of an image
imgradient3 Find 3-D gradient magnitude and direction of images
imgradientxyz Find the directional gradients of a 3-D image
hough Hough transform
houghlines Extract line segments based on Hough transform
houghpeaks Identify peaks in Hough transform
qtdecomp Quadtree decomposition
qtgetblk Block values in quadtree decomposition
qtsetblk Set block values in quadtree decomposition

Examples and How To

Detect Edges in Images

This example shows how to detect edges in an image using both the Canny edge detector and the Sobel edge detector.

Trace Boundaries of Objects in Images

This example shows how to trace the border of an object in a binary image using bwtraceboundary .

Detect Lines in Images Using Hough

This example shows how to detect lines in an image using the hough function.

Perform Quadtree Decomposition on an Image

This example shows how to perform quadtree decomposition on a 512-by-512 grayscale image.

Detect Lines Using the Radon Transform

This example shows how to use the Radon transform to detect lines in an image.

Concepts

Edge Detection

In an image, an edge is a curve that follows a path of rapid change in image intensity.

Hough Transform

The Image Processing Toolbox™ supports functions that enable you to use the Hough transform to detect lines in an image.

Boundary Tracing in Images

The toolbox includes two functions you can use to find the boundaries of objects in a binary image:

Quadtree Decomposition

Quadtree decomposition is an analysis technique that involves subdividing an image into blocks that are more homogeneous than the image itself.

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