mod_para_xld ( Parallels, Image : ModParallels, ExtParallels : Quality, MinGrey, MaxGrey, MaxStandard : )
Extract parallel XLD polygons enclosing a homogeneous area.
mod_para_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 builds 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 parallel lies in the
interval [MinGrey,MaxGrey], 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 witdth of the last area anclosed 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.
Parameters
Parallels (input_object)
|
xld_para-array -> object
|
Input XLD parallels. |
Image (input_object)
|
image -> object
|
Corresponding gray value image. |
ModParallels (output_object)
|
xld_mod_para-array -> object
|
Modified XLD parallels. |
ExtParallels (output_object)
|
xld_ext_para-array -> object
|
Modified XLD parallels. |
Quality (input_control)
|
number -> real / integer
|
Minimum quality factor (measure of parallelism). |
Default value: 0.4 |
Suggested values: 0.1, 0.2, 0.3, 0.4, 0.5, 0.6 |
Restriction: (0.0 <= Quality) && (Quality <= 1.0) |
MinGrey (input_control)
|
integer -> integer
|
Minimum mean gray value. |
Default value: 160 |
Suggested values: 80, 100, 120, 140, 160, 180 |
Restriction: (0 <= MinGrey) && (MinGrey <= 255) |
MaxGrey (input_control)
|
integer -> integer
|
Maximum mean gray value. |
Default value: 220 |
Suggested values: 140, 160, 180, 200, 220, 240 |
Restriction: ((0 <= MaxGrey) && (MaxGrey <= 255)) && (MaxGrey >= MinGrey) |
MaxStandard (input_control)
|
number -> real / integer
|
Maximum allowed standard deviation. |
Default value: 10.0 |
Suggested values: 5.0, 10.0, 15.0, 20.0 |
Restriction: MaxStandard >= 0.0 |
Possible Predecessors
parallels_xld
Possible Successors
max_parallels_xld
See also
info_para_xld
Copyright © 1996-1997 MVTec Software GmbH