Find minimum values in input or sequence of inputs
Computer Vision Toolbox / Statistics
The 2D Minimum block identifies the value, and optionally the position, of the smallest
element in the input. The input can be a vector, a matrix, or an ND array.
The block identifies the minimum value either along a specified dimension of the input or
across the entire input. It also tracks the minimum values in a sequence of inputs over a
period of time when the Mode parameter is set to
Running
.
In
— Input arrayInput array, specified as a vector, matrix, or ND array.
The port is named only when you either select Enable ROI
processing parameter or set the Mode parameter to
Running
.
Data Types: single
 double
 int8
 int16
 int32
 uint8
 uint16
 uint32
 fixed point
Complex Number Support: Yes
Rst
— Reset running minimumReset the running minimum, specified as a scalar. This port specifies the event that causes the block to reset the running minimum. The sample time of the Rst input must be a positive integer and a multiple of the block input sample time.
To enable this port, set the Mode parameter to
Running
and set the Reset port
parameter to Rising edge
, Falling
edge
, Either edge
, or
Nonzero sample
.
Data Types: single
 double
 int8
 int16
 int32
 uint8
 uint16
 uint32
 Boolean
ROI
— Region of interestRegion of interest (ROI), specified as a fourelement vector, mby4 matrix, or MbyN matrix. This port accepts different input values depending on the setting of the ROI type parameter.
Note
You can use the ROI port only if the input to the In port is a 2D image.
You cannot use the ROI port if the
Mode parameter is set to
Running
.
To enable this port, set the Find the minimum value over
parameter to Entire input
and select the Enable
ROI processing parameter.
Data Types: single
 double
 int8
 int16
 int32
 uint8
 uint16
 uint32
 Boolean
 fixed point
Label
— Label matrixLabel matrix, specified as a matrix of nonnegative integers. The label matrix
represents the objects in a 2D image. The pixels labeled 0
are the
background. The pixels labeled 1
make up the first object, the
pixels labeled 2
make up the second object, and so on. The size of
the label matrix must be same as the size of the 2D input image.
To enable this port, select the Enable ROI processing
parameter and set the ROI type parameter to
Label matrix
.
Note
You cannot enable the Label port if the Mode
parameter is set to Running
.
Data Types: uint8
 uint16
 uint32
Label Numbers
— Label values of ROIsLabel values of ROI, specified as an Melement vector. This represents the object names for the corresponding numbers in the label matrix. M must be less than or equal to the number of objects in the label matrix.
To enable this port, select the Enable ROI processing
parameter and set the ROI type parameter to
Label matrix
.
Note
You cannot enable the Label Numbers
port if the
Mode parameter is set to
Running.
Data Types: uint8
 uint16
 uint32
Val
— Minimum values of inputMinimum values of the input, returned as a scalar, vector, matrix, or ND array. The size of this output depends on the size of the input, and the settings of the Mode and Find the minimum value over parameters.
Note
This port is unnamed if the Mode parameter is set to
Running
. It doesn't appear if the
Mode parameter is set to
Index
.
Set the Mode parameter to Value and
Index
or Value
. The block computes the
minimum value along the specified dimension of the input or across the entire input.
The size of the output minimum value depends on the size of the input and the
setting of the Find the Minimum value over parameter.
Scalar — The input is of any size, and the Find the
minimum value over parameter is set to Entire
input
.
Vector — The input is a matrix, and the Find the
minimum value over parameter is set to Each
row
, Each column
, or
Specified dimension
. If Specified
dimension
is selected, the value of the
Dimension parameter must be either
1
or 2
.
(N–1)D array — The input is an ND
array, the Find the minimum value over
parameter is set to Specified dimension
, and the
value of the Dimension parameter is
N.
ND array with one singleton dimension — The input is an
ND array, and the Find the minimum
value over parameter is set to Each row
,
Each column
, or Specified
dimension
. If Specified dimension
is
selected, the value of the Dimension parameter must be an
integer less than N.
Example: For a 3D input array of size MbyNbyP, the dimension of the returned output is:
1byNbyP if you set the
Find the minimum value over parameter
to Entire row
.
Mby1byP if you set the
Find the minimum value over parameter
to Entire column
.
MbyN if you set the Find the minimum value over parameter to
Specified dimension
and the
Dimension parameter to
3
.
Set the Mode parameter to
Running
. The block finds the minimum value of all the
inputs in the given sequence and compiles them into a single array. The output is of
the same size as the input.
Data Types: single
 double
 int8
 int16
 int32
 uint8
 uint16
 uint32
 fixed point
Idx
— Indices of minimum values in the inputIndices of the minimum values in the input array, returned as a scalar, vector, matrix, or ND array.
To enable this port, set the Mode parameter to
Value and Index
or Index
.The
size of the output depends on the size of the input and the setting of the
Find the minimum value over parameter.
Scalar — The input is an Nelement vector, and the
Find the minimum value over parameter is set to
Entire input
.
Vector — The input is a matrix, and the Find the minimum
value over parameter is set to Entire
input
, Each row
, Each
column
, or Specified dimension
. If
Specified dimension
is selected, the value of the
Dimension parameter must be either
1
or 2
.
(N–1)D array — The input is an ND
array, the Find the minimum value over parameter
is set to Specified dimension
, and the value of the
Dimension parameter is N.
ND array with one singleton dimension — The input is an
ND array, and the Find the minimum
value over parameter is set to Each row
,
Each column
, or Specified
dimension
.If Specified dimension
is
selected, the value of the Dimension parameter must be
an integer less than N.
Example: For a 3D input array of size MbyNbyP, the dimension of the returned output is:
1byNbyP if you set the
Find the minimum value over parameter to
Entire row
.
Mby1byP if you set the
Find the minimum value over parameter to
Entire column
.
MbyN if you set the Find the minimum value over parameter to
Specified dimension
and the
Dimension parameter to
3
.
Note
When a minimum value occurs more than once, the computed index corresponds to
the first occurrence. For example, if the input vector is [3 2 1 2
1]
, then the minimum value is 1
and the onebased
index of the minimum value is 3
.
Data Types: single
 double
 int8
 int16
 int32
 int64
 uint8
 uint16
 uint32
 uint64
 fixed point
Flag
— ROI ValidationROI Validation, returned as a scalar or vector of logical 1
s
(true
) or 0
s (false
). If
the ROI type parameter is set to
Rectangles
or Lines
, the
output signifies whether or not the specified ROIs lie completely or partially within
the input image. If the ROI type parameter is set to
Label matrix
, the output signifies whether or not the
label numbers specified in the Label Numbers input are present in
the input label matrix.
ROI type  Individual statistics for each ROI  Single statistics for all ROIs 
Rectangles  The port returns an m element vector,
wherem is the number of rows in the
m4 matrix in the input to the ROI
port. Each element of this vector is a 1 or
0 , indicating that the rectangular ROI is either
completely or partially inside the input image (1 ) or
completely outside the input image (0 ).  The port returns a scalar. The scalar is a 1 or
0 , indicating that any of the rectangles in the
ROI input is present completely or partially inside
(1 ) or completely outside (0 ) the
input image. 
Lines  The port returns a scalar. The scalar is a 1 or
0 , indicating that the input given to the
ROI port is either completely or partially inside
(1 ) the input image or completely outside
(0 ) the input image.  The port returns a scalar. The scalar is a 1 or
0 , indicating that the input given to the
ROI port is either completely or partially inside
(1 ) the input image or completely outside
(0 ) the input image. 
Label matrix  The port returns an Melement vector, where
M is the number of elements in the input to the
Label Numbers port. Each element of the vector is a
1 or 0 , indicating that the
associated label from the Label Numbers input is
present in (1 ) or absent from (0 ) the
Label Matrix input.  The port returns a scalar. The scalar is a 1 or
0 , indicating that any of the labels in the
Label Numbers input are present in
(1 ) or all are absent from (0 ) the
Label Matrix input. 
Note
If the ROI is partially outside the image, the block computes the statistical values for only the portion of the ROI that lies within the image bounds.
To enable this port, select the Output flag indicating if ROI is
within image bounds parameter and set the value of the ROI
type parameter to Rectangle
, or
Lines
, or select the Output flag indicating
if input label numbers are valid parameter and set the value of
ROI type parameter toLabel
matrix
.
Main
Mode
— Output modeValue and Index
(default)  Value
 Index
 Running
Specify the output mode of the block as one of these options.
Value and Index
— Return both the minimum values
and their corresponding indices in the given input.
Value
— Return only the minimum values.
Index
— Return only the indices of the minimum
values in the given input.
Running
— Tracks the minimum values of all input
elements across a sequence of inputs minimum values in a sequence of
inputs.
Index Base
— Index for first elementOne
(default)  Zero
Specify the index for the first element in the input array.
One
for onebased numbering. The range of index
values for each dimension is 1 to m, where m
is the length of that dimension. For example, the index of the first element in a
matrix is (1,1
).
Zero
for zerobased numbering. The range of index
values for each dimension is 0 to m–1, where m
is the length of that dimension. For example, the index of the first element in a
matrix is (0,0
).
Find the minimum value over
— Dimension along which minimum is computedEntire input
(default)  Each row
 Each column
 Specified dimension
Specify the dimension of the input along which the block computes the minimum.
Entire input
— Computes minimum over the
entire input.
Each row
— Computes minimum over each
row.
Each column
— Computes minimum over each
column.
Specified dimension
— Computes minimum over
the dimension specified in the Dimension parameter.
If the Dimension parameter is set to
1
, the output is the same as when Each
column
is selected.
If the Dimension parameter is set to
2
, the output is the same as when Each
row
is selected.
To enable this parameter, set the Mode parameter to
Value and Index
, Value
, or
Index
.
Dimension
— Custom dimension1
(default)  positive scalarSpecify the dimension of the input array over which the block computes the minimum as a onebased value. The value of this parameter must be greater than zero and less than or equal to the number of dimensions in the input array.
To enable this parameter, set the Find the minimum value over
parameter to Specified dimension
.
Reset port
— Reset eventNone
(default)  Rising edge
 Falling edge
 Either edge
 Nonzero sample
Specifies what the block detects as a reset event. The block resets the running minimum when a reset event is detected at the Rst port. The reset sample time must be a positive integer and a multiple of the input sample time.
Specify the reset event as one of these options.
None
— Disable the Rst port.
Rising edge
— Trigger a reset event when the
Rst input does one of the following.
Rises from a negative value to either a positive value or zero
Rises from zero to a positive value, where the rise is not a continuation of a rise from a negative value to zero
Falling edge
— Trigger a reset event when the
Rst input does one of the following.
Falls from a positive value to either a negative value or zero
Falls from zero to a negative value, where the fall is not a continuation of a fall from a positive value to zero
Either edge
— Trigger a reset event when the Rst input is either a Rising
edge
or a Falling edge
.
Nonzero sample
— Trigger a reset event at each
sample time, where the Rst input is not
zero.
Note
When running simulations in Simulink^{®} multitasking mode, reset signals have a onesample latency. In this case, when the block detects a reset event, there is a onesample delay at the Rst port rate before the block applies the reset.
To enable this parameter, set the Mode parameter to
Running
.
Enable ROI processing
— Compute minimum value within ROIoff
(default)  on
Select to calculate the minimum within an ROI in the image.
Note
Full ROI processing is available only if you have a Computer Vision Toolbox™ license. If you do not have a Computer Vision Toolbox license, you can still use ROI processing, but the ROI
type parameter is limited to
Rectangles
.
To enable this parameter, set the Find the minimum value over
parameter to Entire input
.
ROI type
— Format of ROI Rectangles
(default)  Lines
 Label matrix
 Binary mask
Specify the ROI format that represents the regions in the image over which to compute the minimum. The type of ROI can be a rectangle, line, label matrix, or a binary mask.
ROI type  Inputs to the ROI port  Description 
Rectangles 


Lines 


Label matrix  MbyN matrix  Matrix of the same size as the input image. The matrix contains label
values that represent different objects in an image. The pixels labeled
0 are the background. The pixels labeled
1 make up one object, the pixels labeled
2 make up a second object, and so on. 
Binary mask  MbyN matrix  Matrix of the same size as the input image. The binary mask classifies
image pixels as belonging to either the region of interest or the background.
Binary mask values of 1 indicate that the corresponding
image pixel belongs to the ROI. Binary mask values of 0
indicate that the corresponding image pixel is part of the background. 
To enable this parameter, set the Find the minimum value over
parameter to Entire input
and select the Enable
ROI processing parameter.
ROI portion to process
— Portion of ROI in which to calculate minimumEntire ROI
(default)  ROI perimeter
Specify the portion of the ROI for which the block calculates the 2D minimum.
Entire ROI
— The block computes the minimum value
over the entire region of the rectangular ROI.
ROI perimeter
— The block computes the minimum
value along the perimeter of the rectangular ROI.
To enable this parameter, select the Enable ROI processing
parameter and set the ROI type parameter to
Rectangles
.
Output
— Calculate individual or universal minimum for ROIsIndividual statistics for each
ROI
(default)  Single statistic for all ROIs
Specify whether to calculate the 2D minimum individually for each ROI or across all ROIs.
If you select Individual statistics for each ROI
,
the block outputs a vector of minimum values, each element representing an ROI.
The size of the output vector is equal to the number of ROIs.
If you select Single statistic for all ROIs
, the
block outputs a scalar value. The scalar value is the minimum value across all
specified ROIs.
To enable this parameter, select the Enable ROI processing
parameter and set the ROI type parameter to
Rectangles
, Lines
, or
Label matrix
.
Output flag indicating if ROI is within image bounds
— Enable Flag portoff
(default)  on
Select to enable the Flag output port.
Note
The name of this parameter changes to Output flag indicating if input
label numbers are valid when the ROI type
parameter is set to Label matrix
.
To enable this parameter, select the Enable ROI processing
parameter and set the ROI type parameter to
Rectangles
, or Lines
.
Data Types
For details on the fixedpoint block parameters, see Specify FixedPoint Attributes for Blocks.
Lock data type settings against change by the fixedpoint tools
— Prevent fixedpoint tools from overriding data typesoff
(default)  on
Select this parameter to prevent the fixedpoint tools from overriding the data types you specify in this block. For more information, see Lock the Output Data Type Setting (FixedPoint Designer).
Data Types 

Multidimensional Signals 

VariableSize Signals 

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