Documentation

dsp.Minimum System object

Package: dsp

Find minimum values of input or sequence of inputs

Description

The Minimum object finds the minimum value of an input or sequence of inputs.

To compute the minimum value of an input or sequence of inputs:

  1. Define and set up your System object™. See Construction.

  2. Call step to compute the minimum according to the properties of dsp.Minimum. The behavior of step is specific to each object in the toolbox.

Construction

H = dsp.Minimum returns an object, H, that computes the value and/or index of the minimum elements in an input or a sequence of inputs over the specified Dimension.

H = dsp.Minimum('PropertyName',PropertyValue,...) returns a minimum-finding object, H, with each specified property set to the specified value.

Properties

ValueOutputPort

Output minimum value

Set this property to true in order to output the minimum value of the input. This property applies only when you set theRunningMinimum property to false. The default is true.

RunningMinimum

Calculate over single input or multiple inputs

When you set this property to true, the object computes the minimum value over successive calls to the step method. When you set this property to false, the object computes the minimum value over the current input. The default is false.

IndexOutputPort

Output index of minimum value

Set this property to true to output the index of the minimum value of the input. This property applies only when you set the RunningMinimum property to false. The default is true.

ResetInputPort

Additional input to enable resetting of running minimum

Set this property to true to enable resetting of the running minimum. When you set this property to true, you must specify a reset input to the step method to reset the running minimum. This property applies only when you set the RunningMinimum property to true. The default is false.

ResetCondition

Condition that triggers resetting of running minimum

Specify the event that resets the running minimum as one of | Rising edge | Falling edge | Either edge | Non-zero |. This property applies only when you set the ResetInputPort property to true. The default is Non-zero.

IndexBase

Numbering base for index of minimum value

Specify the numbering used when computing the index of the minimum value as starting from either One or Zero. This property applies only when you set the IndexOutputPort property to true. The default is One.

Dimension

Dimension to operate along

Specify how the minimum calculation is performed over the data as one of | All | Row | Column | Custom |. This property applies when you set the RunningMinimum property to false. The default is Column.

CustomDimension

Numerical dimension to calculate over

Specify the integer dimension of the input signal over which the object finds the minimum. The cannot exceed the number of dimensions in the input signal. This property only applies when you set the Dimension property to Custom. The default is 1.

ROIProcessing

Enable region-of-interest processing

Set this property to true to enable calculation of the minimum value within a particular region of an image. This property applies when you set the Dimension property to All and the RunningMinimum property to false. The default is false.

For full ROI processing support, install the Computer Vision System Toolbox™ product. If you only have the DSP System Toolbox™ product installed, you can only specify the value of the ROIForm property as Rectangles.

ROIForm

Type of region of interest

Specify the type of region of interest as one of | Rectangles | Lines | Label matrix | Binary mask |. This property applies only when you set the ROIProcessing property to true. The default is Rectangles.

For full ROI processing support, install the Computer Vision System Toolbox product. If you have only the DSP System Toolbox product installed, you can only specify the as Rectangles.

ROIPortion

Calculate over entire ROI or just perimeter

Specify whether to calculate the minimum over the Entire ROI or the ROI perimeter. This property applies only when you set the ROIForm property to Rectangles. The default is Entire ROI.

ROIStatistics

Calculate statistics for each ROI or one for all ROIs

Specify whether to calculate Individual statistics for each ROI or a Single statistic for all ROIs. This property applies only when you set the ROIForm property to Rectangles, Lines, or Label matrix.

ValidityOutputPort

Output flag indicating if any part of ROI is outside input image

When you set the ROIForm property to Lines or Rectangles, set this property to true to return the validity of the specified ROI being completely inside of the image. When you set the ROIForm property to Label Matrix, set this property to true to return the validity of the specified label numbers. The default is false.

FrameBasedProcessing

Process input as frames or samples

Set this property to true to enable frame-based processing for 2-D inputs. Set this property to false to enable sample-based processing. The object always performs sample-based processing for N-D inputs where N is greater than 2. This property applies when you set the RunningMinimum to true. The default is true.

 Fixed-Point Properties

Methods

cloneCreate minimum-finding object with same property values
getNumInputsNumber of expected inputs to step method
getNumOutputsNumber of outputs of step method
isLockedLocked status for input attributes and nontunable properties
releaseAllow property value and input characteristics changes
resetReset internal states of minimum-finding object
stepOperate on inputs to calculate outputs

Examples

Find a minimum value and its index:

 hmin1 = dsp.Minimum;
 x = randn(100,1);
 [y, I] = step(hmin1, x);

Compute a running minimum:

 hmin2 = dsp.Minimum;
 hmin2.RunningMinimum = true;
 x = randn(100,1);
 y = step(hmin2, x); 
 % y(i) is the minimum of all values in the vector x(1:i)

Algorithms

This object implements the algorithm, inputs, and outputs described on the Minimum block reference page. The object properties correspond to the block parameters, except:

Treat sample-based row input as a column block parameter is not supported by the dsp.Minimum object.

Both this object and its corresponding block let you specify whether to process inputs as individual samples or as frames of data. The object uses the FrameBasedProcessing property. The block uses the Input processing parameter. See Set the FrameBasedProcessing Property of a System object for more information.

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