The Line Pattern module is used to detect specific low/high pixel combinations present within
the image not unlike those patterns exhibited by barcodes. While barcodes have their
own specific configurations it is often useful to be able to scan for patterns that
are not necessarily barcodes but provide a unique pattern within the image. This
module can be useful for identifying patterns that are obscured in part due to
other objects that would cause complete object identification to fail.
This module assumes a black and white image (thresholded) in order to find patterns. If a colored or grayscale
image is provided, the module will assume all values below 128 are black and above 128 to be white.
1. Line Pattern - Specify the line pattern using numbers that indicate the
expected lengths of light/dark/light/dark/etc. transitions. For example
the pattern 2 4 1 4 2 would indicate a white run of 2 units, followed by
a black run of 4 units, followed by a white run of 1 unit, etc.
If you have an existing sample of the pattern already loaded you can use
the Select Pattern button to indicate the line pattern that you wish to
find. Once selected the Line Pattern number sequence will automatically
be created based on the selected sample.
2. Visual - The black and white line graphic visually depicts the information in
the line pattern data. When the pattern is changed the
2. Pattern has border units - The default pattern mode assumes that is begins on a white
pattern with a minimum 1 pixel border. In many cases larger border areas can be used
to isolate true patterns form false patterns. By enabling border units the pattern
can be augmented with start and stop unit values that specify the minimum space required
around the pattern for it to have a high confidence.
3. Confidence - Specify the level of confidence that should be expected
for a pattern match to be considered a valid match. The confidence is based
on how precisely the image sequence matches the lengths specified in the Line Pattern.
4. Pattern has border Units - Pattern includes border lengths that can be larger than
the specified amount but not less than. This allows a pattern to have silent areas around
the actual pattern.
5. Overlay on - Specify which image the graphics should be show on. This option allows you
to show the source image that generated the pattern.
6. Line Match Color - The color used to indicate which lines match the pattern.
7. Box Color - The color used to indicate the grouping results of the line patterns.
8. Thickness - The thickness of the line used in the box drawing.
9. Font Size - The font sized used to annotate the confidence display.
10. Display as Annotation - Select if you want the graphic to be draw after all processing has been
completed. If this is NOT selected then the next module in the processing pipeline will see the graphic as if
it were part of the image and process it accordingly.
11. Remove non matching Lines - To remove most of the image that is not matched by the
pattern select the "remove" checkbox. This will remove all white lines that do NOT
match the pattern. This can be used to isolate the sought out pattern for
further processing without any other parts of the image being present.
12. Padding - How much space to include around the line patterns to use in grouping.
13. Min/Max Length - Used to filter line patterns matches that are too small or too long
to be valid.
14. Min/Max Angle - The minimum and maximal angles to check for the line pattern.
15. Angle Increment - The increment to use when testing from the minimum to maximum
angles. Large numbers will speed up detection but reduce precision.
16. Merge Overlap - Line patterns that are detected next to each other can be grouped to
create a single final result. The Overlap percentage specifies how much of the lines
need to overlap in order to be merged. 0 % will merge any lines that overlap, 100% will
keep them separate.
17. Min Merged Count - The minimum number of merged lines required for a result to be
declared. This ensures that there are enough line pattern matches to declare a result
and is used to eliminate false matches.
18. Select Pattern - As the creation of the line pattern using just numbers can be difficult,
you can press the Select Pattern button which will allow you to specify the line to sample
and create the number pattern for you.
LINE_PATTERN_COUNT - number of found line patterns (combined into a
single overlapping block)
LINE_PATTERN - the results of the pattern match
The array contains blocks of 8 values per detected pattern. The elements
are as follows:
0 score of the pattern (1-100)
1 x coordinate of the center of the pattern
2 y coordinate of the center of the pattern
3 size in percent * 10 of the detected
pattern relative to the source pattern
4 x start coordinate of the pattern
5 y start coordinate of the pattern
6 x end coordinate of the pattern
7 y end coordinate of the pattern
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