# detectHarrisFeatures

Detect corners using Harris–Stephens algorithm

## Description

example

points = detectHarrisFeatures(I) returns a cornerPoints object points that contains information about corner features detected in the 2-D grayscale input using the Harris-Stephens algorithm.

points = detectHarrisFeatures(I,Name,Value) uses additional options specified by one or more Name,Value pair arguments.

## Examples

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I = checkerboard;

Find the corners.

corners = detectHarrisFeatures(I);

Display the results.

imshow(I); hold on;
plot(corners.selectStrongest(50));

## Input Arguments

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Input image, specified is an M-by-N 2-D image. The input image must be real and nonsparse.

Data Types: single | double | int16 | uint8 | uint16 | logical

### Name-Value Arguments

Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Before R2021a, use commas to separate each name and value, and enclose Name in quotes.

Example: 'MinQuality','0.01','ROI', [50,150,100,200] specifies that the detector must use a 1% minimum accepted quality of corners within the designated region of interest. This region of interest is located at x=50, y=150. The ROI has a width of 100 pixels and a height of 200 pixels.

Minimum accepted quality of corners, specified as the comma-separated pair consisting of 'MinQuality' and a scalar value in the range [0,1].

The minimum accepted quality of corners represents a fraction of the maximum corner metric value in the image. Larger values can be used to remove erroneous corners.

Example: 'MinQuality', 0.01

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

Gaussian filter dimension, specified as the comma-separated pair consisting of 'FilterSize' and an odd integer value in the range [3, min(size(I))].

The Gaussian filter smooths the gradient of the input image.

The function uses the FilterSize value to calculate the filter’s dimensions, FilterSize-by-FilterSize. It also defines the standard deviation of the Gaussian filter as FilterSize/3.

Example: 'FilterSize', 5

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

Rectangular region for corner detection, specified as a comma-separated pair consisting of 'ROI' and a vector of the format [x y width height]. The first two integer values [x y] represent the location of the upper-left corner of the region of interest. The last two integer values represent the width and height.

Example: 'ROI', [50,150,100,200]

## Output Arguments

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Corner points object, returned as a cornerPoints object. The object contains information about the feature points detected in the 2-D input image.

## References

[1] Harris, C., and M. Stephens, "A Combined Corner and Edge Detector," Proceedings of the 4th Alvey Vision Conference, August 1988, pp. 147-151.

## Version History

Introduced in R2013a