Operator Reference
mod_parallels_xld (Operator)
mod_parallels_xld — Extract parallel XLD polygons enclosing a homogeneous area.
Signature
mod_parallels_xld(Parallels, Image : ModParallels, ExtParallels : Quality, MinGray, MaxGray, MaxStandard : )
Description
mod_parallels_xld selects XLD parallels enclosing
homogeneous areas from the input parallels Parallels.
The parameter Image contains the corresponding gray value
image.
Only parallels having a quality factor larger than
Quality are examined. The algorithm performs parallel
cross sections one pixel apart, and parallel to the line segments in
the area of overlap between two parallel line segments.
In the first iteration, the mean gray value for each of the lines in the cross section is calculated. In the second iteration, the standard deviations of the gray values along each line are computed.
If the mean gray value of an area between parallels lies in the
interval [MinGray,MaxGray], and if the mean of
all standard deviations is smaller than the upper threshold
MaxStandard, the corresponding parallels are returned as
modified parallels in ModParallels.
In a second step, all polygon segments adjacent to parallels
bordering homogeneous areas are checked for homogeneity. To do so,
a rectangle having the width of the last area enclosed by a
modified parallel is constructed, and checked for homogeneity using
the algorithm described above. This process is continued as long as
there are adjacent polygon segments. The polygons thus found are
returned as extended parallels in ExtParallels.
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
Parallels (input_object) xld_para-array → object
Input XLD parallels.
Image (input_object) singlechannelimage → object (byte)
Corresponding gray value image.
ModParallels (output_object) xld_mod_para-array → object
Modified XLD parallels.
ExtParallels (output_object) xld_ext_para-array → object
Extended XLD parallels.
Quality (input_control) number → (real / integer)
Minimum quality factor (measure of parallelism).
Default: 0.4
Suggested values: 0.1, 0.2, 0.3, 0.4, 0.5, 0.6
Restriction:
0.0 <= Quality && Quality <= 1.0
MinGray (input_control) integer → (integer)
Minimum mean gray value.
Default: 160
Suggested values: 80, 100, 120, 140, 160, 180
Restriction:
0 <= MinGray && MinGray <= 255
MaxGray (input_control) integer → (integer)
Maximum mean gray value.
Default: 220
Suggested values: 140, 160, 180, 200, 220, 240
Restriction:
0 <= MaxGray && MaxGray <= 255 && MaxGray >= MinGray
MaxStandard (input_control) number → (real / integer)
Maximum allowed standard deviation.
Default: 10.0
Suggested values: 5.0, 10.0, 15.0, 20.0
Restriction:
MaxStandard >= 0.0
Possible Predecessors
Possible Successors
See also
Module
Foundation