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vision.StandardDeviation System object

Find standard deviation values in input or sequence of inputs

Description

Find the standard deviation values in an input or sequence of inputs.

To track a set of points:

  1. Create the vision.StandardDeviation object and set its properties.

  2. Call the object with arguments, as if it were a function.

To learn more about how System objects work, see What Are System Objects? (MATLAB).

Creation

Syntax

stdDev = vision.StandardDeviation
stdDev = vision.StandardDeviation(Name,Value)

Description

example

stdDev = vision.StandardDeviation returns an object, stdDev, that computes the value and index of the maximum elements in an input or a sequence of inputs.

stdDev = vision.StandardDeviation(Name,Value) sets properties using one or more name-value pairs. Enclose each property name in quotes. For example, stdDev = vision.Maximum('RunningStandardDeviation',false)

Properties

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Unless otherwise indicated, properties are nontunable, which means you cannot change their values after calling the object. Objects lock when you call them, and the release function unlocks them.

If a property is tunable, you can change its value at any time.

For more information on changing property values, see System Design in MATLAB Using System Objects (MATLAB).

Output standard deviation value, specified as true or false. Set this property to true to output the Minimum value of the input. This property applies when you set the RunningStandardDeviation property to false.

Calculate over single input or multiple inputs, specified as true or false. When you set this property to true, the object computes the standard deviation value over a sequence of inputs. When you set this property to false, the object computes the standard deviation value over the current input.

Additional input to enable resetting of running standard deviation, specified as true or false. When you set this property to true, a reset input must be specified to reset the running standard deviation. This property applies only when you set the RunningStandardDeviation property to true.

Condition that triggers resetting of running standard deviation, specified as as 'Rising edge', 'Falling edge', 'Either edge', or 'Non-zero'. This property applies only when you set the ResetInputPort property to true.

Dimension to operate along, specified as {'All'}, 'Row', 'Column', or 'Custom'. This property applies only when you set the RunningStandardDeviation property to false.

Numerical dimension to calculate over, specified as a numerical scalar. This property only applies when you set the Dimension property to 'Custom'.

Enable region-of-interest processing, specified as true or false. This property applies when you set the Dimension property to 'All' and the RunningStandardDeviation property to false.

Type of ROI, specified as 'Rectangles', 'Lines', 'Label matrix', or 'Binary mask'. This property applies only when you set the ROIProcessing property to true.

ROI or perimeter calculation, specified as 'Entire ROI' or 'ROI perimeter'. This property applies only when you set the ROIForm property to 'Rectangles'.

Calculate statistics for each ROI or one for all ROIs, specified as 'Individual statistics for each ROI' or 'Single statistic for all ROIs'. This property applies only when you set the 'ROIForm' property to 'Rectangles', 'Lines', or 'Label matrix'.

Flag to indicate if any part of ROI is outside input image, specified as true or false.

This applies when you set the ROIForm property to 'Lines' or 'Rectangles'.

Set this property to true to return the validity of the specified label numbers. This applies when you set the ROIForm property to 'Label matrix'.

Usage

For versions earlier than R2016b, use the step function to run the System object™ algorithm. The arguments to step are the object you created, followed by the arguments shown in this section.

For example, y = step(obj,x) and y = obj(x) perform equivalent operations.

Syntax

[value,index] = stdDev(input)
index = stdDev(input)
[___] = stdDev(I,ROI)
[___,flag] = stdDev(I,ROI)
[___] = stdDev(I,label,labelNumbers)
[___,flag] = stdDev(I,label,labelNumbers)

Description

example

[value,index] = stdDev(input) returns the standard deviation value and index of the input.

index = stdDev(input) returns the one-based index of the standard deviation value when you set the IndexOutputPort property to true and the ValueOutputPort property to false. The RunningStandardDeviation property must be set to false.

[___] = stdDev(I,ROI) returns the standard deviation value in the input image within the given region of interest.

[___,flag] = stdDev(I,ROI)additionally returns a flag to indicate whether the given ROI is within the bounds of the image.

[___] = stdDev(I,label,labelNumbers) returns the standard deviation of the input image for a region the labels specified in the labelNumbers vector. The regions are defined and labeled in the label matrix.

[___,flag] = stdDev(I,label,labelNumbers) additionally returns a flag to indicate whether the input label numbers are valid.

Input Arguments

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Input data, specified as a vector, matrix, or multidimensional array.

Region of interest, specified as a four-element vector, [x y width height]. This option is available when you set the the ROIProcessing property to true and the ROIForm property to 'Lines', 'Rectangles', or 'Binary Mask'.

Label numbers, specified as a matrix. This option is available when you set the ROIProcessing property to true and the ROIForm property to 'Label matrix'.

Label numbers, specified as a vector. This option is available when you set the ROIProcessing property to true and the ROIForm property to 'Label matrix'.

Output Arguments

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Minimum value, returned as the same data type as the input

Index to standard deviation value, returned as a one-based index.

Flag for valid data, returned as true or false.

Object Functions

To use an object function, specify the System object as the first input argument. For example, to release system resources of a System object named obj, use this syntax:

release(obj)

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stepRun System object algorithm
releaseRelease resources and allow changes to System object property values and input characteristics
resetReset internal states of System object

Examples

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Read a color image.

img = imread('peppers.png');

Convert the image to grayscale.

img = im2single(rgb2gray(img));

Find the standard deviation.

stdDev = vision.StandardDeviation;
stdDevValue = stdDev(img);

Extended Capabilities

Introduced in R2012a