# Documentation

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

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