point_in_line ( Image : : Background, Threshold, Row, Col, LocalDistance, Significance : Exist, BeginRow, BeginCol, EndRow, EndCol )
Check whether a pixel belongs to a line.
The operator point_in_line checks whether the indicated pixel
(Row,Col) lies on a straight line in the gray scale
image (Image) and, if necessary, returns the existence of the line
(Exist = 1) and the maximum straight part
of a line with a starting (BeginRow,BeginCol)
and an ending point (EndRow,EndCol).
The brightness of the background is given by Background.
Threshold determines the boundary of the gray value between
foreground and background. LocalDistance is a rectangle which
defines a region around the pixel.
For this rectangle surrounding the pixel a Hough transformation is performed
in order to find out whether the pixel is on the line.
Then this line is detected within the image. The difference of the local
maximum value in the Hough image to the mean value
can be determined by Significance.
Parameters
Image (input_object)
|
image(-array) -> object : byte
|
Input image. |
Background (input_control)
|
string -> string
|
Brightness of background. |
Default value: 'dark' |
List of values: 'dark', 'light' |
Threshold (input_control)
|
integer -> integer
|
Threshold value. |
Default value: 110 |
Suggested values: 10, 30, 50, 70, 90, 110, 130, 150, 170, 190, 210, 230, 250 |
Range of values: 1 <= Threshold <= 255 |
Minimum increment: 1
|
Recommended increment: 1
|
Restriction: Threshold >= 0 |
Row (input_control)
|
point.y -> integer
|
Line coordinate of pixel to be examined. |
Col (input_control)
|
point.x -> integer
|
Column coordinate of pixel to be examined. |
LocalDistance (input_control)
|
integer -> integer
|
Distance of the pixel to be examined to the edges
of the surrounding rectangle. |
Default value: 20 |
Suggested values: 10, 15, 20, 25, 30 |
Range of values: 5 <= LocalDistance <= 30 |
Minimum increment: 1
|
Recommended increment: 1
|
Restriction: LocalDistance >= 0 |
Significance (input_control)
|
integer -> integer
|
Maximum difference of the local maximum value in the
Hough image to the mean value |
Restriction: Significance >= 0 |
Exist (output_control)
|
integer -> integer
|
Indication of existence of a line (0:no, 1:yes). |
BeginRow (output_control)
|
line.begin.y -> integer
|
Line coordinate of the starting point of
the output line. |
BeginCol (output_control)
|
line.begin.x -> integer
|
Column coordinate of the starting point of
the output line. |
EndRow (output_control)
|
line.end.y -> integer
|
Line coordinate of the ending point of the output
line. |
EndCol (output_control)
|
line.end.x -> integer
|
Column coordinate of the ending point of the output
line. |
Example
point_in_line
(Image,1,100,3,10,20,&Exist,&RowBegin,&ColBegin,&RowEnd,&ColEnd);
t_dist_line(RowBegin,ColBegin,RowEnd,ColEnd);
Result
If the parameter values are correct the operator point_in_line
returns the value TRUE.
The behavior in case of empty input (no input objects available) is set via
the operator set_system(::'no_object_result',<Result>:).
If necessary an exception is raised.
Possible Predecessors
sigma__,
median
Possible Successors
select_lines1,
select_lines1,
select_longest_lines,
line_position,
line_orientation
Copyright © 1996-1997 MVTec Software GmbH