measure_threshT_measure_threshMeasureThreshMeasureThreshmeasure_thresh (Operator)
Name
measure_threshT_measure_threshMeasureThreshMeasureThreshmeasure_thresh — Extracting points with a particular gray value along a rectangle or an
annular arc.
Signature
void MeasureThresh(const HObject& Image, const HTuple& MeasureHandle, const HTuple& Sigma, const HTuple& Threshold, const HTuple& Select, HTuple* RowThresh, HTuple* ColumnThresh, HTuple* Distance)
void HMeasure::MeasureThresh(const HImage& Image, double Sigma, double Threshold, const HString& Select, HTuple* RowThresh, HTuple* ColumnThresh, HTuple* Distance) const
void HMeasure::MeasureThresh(const HImage& Image, double Sigma, double Threshold, const char* Select, HTuple* RowThresh, HTuple* ColumnThresh, HTuple* Distance) const
void HMeasure::MeasureThresh(const HImage& Image, double Sigma, double Threshold, const wchar_t* Select, HTuple* RowThresh, HTuple* ColumnThresh, HTuple* Distance) const
(
Windows only)
void HImage::MeasureThresh(const HMeasure& MeasureHandle, double Sigma, double Threshold, const HString& Select, HTuple* RowThresh, HTuple* ColumnThresh, HTuple* Distance) const
void HImage::MeasureThresh(const HMeasure& MeasureHandle, double Sigma, double Threshold, const char* Select, HTuple* RowThresh, HTuple* ColumnThresh, HTuple* Distance) const
void HImage::MeasureThresh(const HMeasure& MeasureHandle, double Sigma, double Threshold, const wchar_t* Select, HTuple* RowThresh, HTuple* ColumnThresh, HTuple* Distance) const
(
Windows only)
static void HOperatorSet.MeasureThresh(HObject image, HTuple measureHandle, HTuple sigma, HTuple threshold, HTuple select, out HTuple rowThresh, out HTuple columnThresh, out HTuple distance)
void HMeasure.MeasureThresh(HImage image, double sigma, double threshold, string select, out HTuple rowThresh, out HTuple columnThresh, out HTuple distance)
void HImage.MeasureThresh(HMeasure measureHandle, double sigma, double threshold, string select, out HTuple rowThresh, out HTuple columnThresh, out HTuple distance)
Description
measure_threshmeasure_threshMeasureThreshMeasureThreshMeasureThreshmeasure_thresh extracts points for which the gray value
within an one-dimensional gray value profile is equal to the specified
threshold ThresholdThresholdThresholdThresholdthresholdthreshold. The gray value profile is projected
onto the major axis of the measure rectangle which is passed with
the parameter MeasureHandleMeasureHandleMeasureHandleMeasureHandlemeasureHandlemeasure_handle, so the threshold points
calculated within the gray value profile correspond to certain image
coordinates on the rectangle's major axis. These coordinates are
returned as the operator results in RowThreshRowThreshRowThreshRowThreshrowThreshrow_thresh and
ColumnThreshColumnThreshColumnThreshColumnThreshcolumnThreshcolumn_thresh.
For an explanation of the concept of 1D measuring see the introduction of
chapter 1D Measuring.
If the gray value profile intersects the threshold line for several times,
the parameter SelectSelectSelectSelectselectselect determines which values to return.
Possible settings are 'first'"first""first""first""first""first", 'last'"last""last""last""last""last",
'first_last'"first_last""first_last""first_last""first_last""first_last" (first and last) or 'all'"all""all""all""all""all". For the
last two cases DistanceDistanceDistanceDistancedistancedistance returns the distances between
the calculated points.
The gray value profile is created by averaging the gray values along
all line segments, which are defined by the measure rectangle as follows:
-
The segments are perpendicular to the major axis of the rectangle,
-
they have an integer distance to the center of the rectangle,
-
the rectangle bounds the segments.
For every line segment, the average of the gray values of all points
with an integer distance to the major axis is calculated.
Due to translation and rotation of the measure rectangle with respect to
the image coordinates the input image ImageImageImageImageimageimage is in general
sampled at subpixel positions.
Since this involves some calculations which can be used repeatedly
in several projections, the operator gen_measure_rectangle2gen_measure_rectangle2GenMeasureRectangle2GenMeasureRectangle2GenMeasureRectangle2gen_measure_rectangle2
is used to perform these calculations only once in advance. Here,
the measure object MeasureHandleMeasureHandleMeasureHandleMeasureHandlemeasureHandlemeasure_handle is generated and different
interpolation schemes can be selected.
Attention
measure_threshmeasure_threshMeasureThreshMeasureThreshMeasureThreshmeasure_thresh only returns meaningful results if the
assumptions that the edges are straight and perpendicular to the
major axis of the rectangle are fulfilled. Thus, it should not be
used to extract edges from curved objects, for example.
Furthermore, the user should ensure that the rectangle is as close
to perpendicular as possible to the edges in the image. Additionally,
SigmaSigmaSigmaSigmasigmasigma must not become larger than approx. 0.5 * Length1
(for Length1 see gen_measure_rectangle2gen_measure_rectangle2GenMeasureRectangle2GenMeasureRectangle2GenMeasureRectangle2gen_measure_rectangle2).
It should be kept in mind that measure_threshmeasure_threshMeasureThreshMeasureThreshMeasureThreshmeasure_thresh ignores the
domain of ImageImageImageImageimageimage for efficiency reasons. If certain regions
in the image should be excluded from the measurement a new measure
object with appropriately modified parameters should be generated.
Execution Information
- Multithreading type: reentrant (runs in parallel with non-exclusive operators).
- Multithreading scope: global (may be called from any thread).
- Processed without parallelization.
Parameters
ImageImageImageImageimageimage (input_object) singlechannelimage → objectHImageHObjectHImageHobject (byte / uint2 / real)
Input image.
MeasureHandleMeasureHandleMeasureHandleMeasureHandlemeasureHandlemeasure_handle (input_control) measure → HMeasure, HTupleHHandleHTupleHtuple (handle) (IntPtr) (HHandle) (handle)
Measure object handle.
SigmaSigmaSigmaSigmasigmasigma (input_control) number → HTuplefloatHTupleHtuple (real) (double) (double) (double)
Sigma of gaussian smoothing.
Default:
1.0
Suggested values:
0.0, 0.4, 0.6, 0.8, 1.0, 1.5, 2.0, 3.0, 4.0, 5.0, 7.0, 10.0
Value range:
0.0
≤
Sigma
Sigma
Sigma
Sigma
sigma
sigma
≤
100 (lin)
Minimum increment:
0.01
Recommended increment:
0.1
ThresholdThresholdThresholdThresholdthresholdthreshold (input_control) number → HTuplefloatHTupleHtuple (real) (double) (double) (double)
Threshold.
Default:
128.0
Value range:
0
≤
Threshold
Threshold
Threshold
Threshold
threshold
threshold
≤
255 (lin)
Minimum increment:
0.5
Recommended increment:
1
SelectSelectSelectSelectselectselect (input_control) string → HTuplestrHTupleHtuple (string) (string) (HString) (char*)
Selection of points.
Default:
'all'
"all"
"all"
"all"
"all"
"all"
List of values:
'all'"all""all""all""all""all", 'first'"first""first""first""first""first", 'first_last'"first_last""first_last""first_last""first_last""first_last", 'last'"last""last""last""last""last"
RowThreshRowThreshRowThreshRowThreshrowThreshrow_thresh (output_control) point.y-array → HTupleSequence[float]HTupleHtuple (real) (double) (double) (double)
Row coordinates of points with threshold value.
ColumnThreshColumnThreshColumnThreshColumnThreshcolumnThreshcolumn_thresh (output_control) point.x-array → HTupleSequence[float]HTupleHtuple (real) (double) (double) (double)
Column coordinates of points with threshold value.
DistanceDistanceDistanceDistancedistancedistance (output_control) real-array → HTupleSequence[float]HTupleHtuple (real) (double) (double) (double)
Distance between consecutive points.
Result
If the parameter values are correct the operator measure_threshmeasure_threshMeasureThreshMeasureThreshMeasureThreshmeasure_thresh
returns the value 2 (
H_MSG_TRUE)
. Otherwise, an exception is raised.
Possible Predecessors
gen_measure_rectangle2gen_measure_rectangle2GenMeasureRectangle2GenMeasureRectangle2GenMeasureRectangle2gen_measure_rectangle2
Possible Successors
close_measureclose_measureCloseMeasureCloseMeasureCloseMeasureclose_measure
Alternatives
measure_posmeasure_posMeasurePosMeasurePosMeasurePosmeasure_pos,
edges_sub_pixedges_sub_pixEdgesSubPixEdgesSubPixEdgesSubPixedges_sub_pix,
measure_pairsmeasure_pairsMeasurePairsMeasurePairsMeasurePairsmeasure_pairs
Module
1D Metrology