set_fuzzy_measure (Operator)

Name

set_fuzzy_measure — Specify a fuzzy function.

Signature

set_fuzzy_measure( : : MeasureHandle, SetType, Function : )

Description

set_fuzzy_measure specifies a fuzzy function passed in Function. The specified fuzzy functions enable fuzzy_measure_pos and fuzzy_measure_pairs / fuzzy_measure_pairing to evaluate and select the detected edge candidates. For this purpose, weighting characteristics for different edge features can be defined by one function each. Such a specified feature is called fuzzy set. Specifying no function for a fuzzy set means not to use this feature for the final edge evaluation. Setting a second fuzzy function to a set means to discard the first defined function and replace it by the second one. A previously defined fuzzy function can be discarded completely by reset_fuzzy_measure.

For an explanation of the concept of 1D measuring see the introduction of chapter 1D Measuring.

Functions for five different fuzzy set types selected by the SetType parameter can be defined, the sub types of a set being mutual exclusive:

• 'contrast' will use the fuzzy function to evaluate the amplitudes of the edge candidates. When extracting edge pairs, the fuzzy evaluation is obtained by the geometric average of the fuzzy contrast scores of both edges.

• The fuzzy function of 'position' evaluates the distance of each edge candidate to the reference point of the measure object, generated by gen_measure_arc or gen_measure_rectangle2. The reference point is located at the beginning whereas 'position_center' or 'position_end' sets the reference point to the middle or the end of the one-dimensional gray value profile instead. If the fuzzy position evaluation depends on the position of the object along the profile, 'position_first_edge' / 'position_last_edge' sets the reference point at the position of the first/last extracted edge. When extracting edge pairs the position of a pair is referenced by the geometric average of the fuzzy position scores of both edges.

• Similar to 'position', 'position_pair' evaluates the distance of each edge pair to the reference point of the measure object. The position of a pair is defined by the center point between both edges. The object's reference can be set by 'position_pair_center', 'position_pair_end' and 'position_first_pair', 'position_last_pair', respectively. Contrary to 'position', this set is only used by fuzzy_measure_pairs/fuzzy_measure_pairing.

• 'size' denotes a fuzzy set that evaluates the normed distance of the two edges of a pair in pixels. This set is only used by fuzzy_measure_pairs/fuzzy_measure_pairing. Specifying an upper bound for the size by terminating the function with a corresponding fuzzy value of 0.0 will speed up fuzzy_measure_pairs / fuzzy_measure_pairing because not all possible pairs need to be considered.

• 'gray' sets a fuzzy function to weight the mean projected gray value between two edges of a pair. This set is only used by fuzzy_measure_pairs / fuzzy_measure_pairing.

A fuzzy function is defined as a piecewise linear function by at least two pairs of values, sorted in an ascending order by their x value. The x values represent the edge feature and must lie within the parameter space of the set type, i.e., in case of 'contrast' and 'gray' feature and, e.g., byte images within the range 0.0 <= x <= 255.0. In case of 'size' x has to satisfy 0.0 <= x whereas in case of 'position' x can be any real number. The y values of the fuzzy function represent the weight of the corresponding feature value and have to satisfy the range of 0.0 <= y <= 1.0. Outside of the function's interval, defined by the smallest and the greatest x value, the y values of the interval borders are continued constantly. Such Fuzzy functions can be generated by create_funct_1d_pairs.

If more than one set is defined, fuzzy_measure_pos / fuzzy_measure_pairs / fuzzy_measure_pairing yield the overall fuzzy weighting by the geometric middle of the weights of each set.

Execution Information

• Multithreading type: reentrant (runs in parallel with non-exclusive operators).
• Processed without parallelization.

This operator modifies the state of the following input parameter:

During execution of this operator, access to the value of this parameter must be synchronized if it is used across multiple threads.

Parameters

MeasureHandle (input_control, state is modified)  measure (handle)

Measure object handle.

SetType (input_control)  string (string)

Selection of the fuzzy set.

Default value: 'contrast'

List of values: 'contrast', 'gray', 'position', 'position_center', 'position_end', 'position_first_edge', 'position_first_pair', 'position_last_edge', 'position_last_pair', 'position_pair_center', 'position_pair_end', 'size'

Function (input_control)  function_1d (real / integer)

Fuzzy function.

Example (HDevelop)

* how to use a fuzzy function
* ...
gen_measure_rectangle2 (50, 100, 0, 200, 100, 512, 512, 'nearest_neighbor', \
MeasureHandle)
* create a generalized fuzzy function to evaluate edge pairs
* * (30% uncertainty).
create_funct_1d_pairs ([0.7,1.0,1.3], [0.0,1.0,0.0], SizeFunction)
* and transform it to expected size of 13.45 pixels
transform_funct_1d (SizeFunction, [1.0,0.0,13.45,0.0], TransformedFunction)
set_fuzzy_measure (MeasureHandle, 'size', TransformedFunction)

fuzzy_measure_pairs (Image, MeasureHandle, 1, 30, 0.5, 'all', RowEdgeFirst, \
ColumnEdgeFirst, AmplitudeFirst, RowEdgeSecond, \
ColumnEdgeSecond, AmplitudeSecond, RowEdgeCenter, \