Operator Reference
fast_match_mg (Operator)
fast_match_mg — Searching all good gray value matches in a pyramid.
Warning
fast_match_mg is obsolete and is only provided for
reasons of backward compatibility.
The operator will be removed with HALCON 25.11.
New applications should use the
shape-based or NCC-based operators instead.
Signature
fast_match_mg(Image : Matches : TemplateID, MaxError, NumLevel : )
Description
The operator fast_match_mg like the operator
fast_match performs a matching of the template of
TemplateID and Image.
In contrast to fast_match, however, the search for
good matches starts in scaled down images (pyramid).
The number of levels of the pyramid will be determined by
NumLevel.
Hereby the value 1 indicates that no pyramid will be used.
In this case the operator fast_match_mg is
equivalent to the operator fast_match. The value
2 triggers the search in the image with half the framesize.
The search for all those points showing an error small enough
in the scaled down image (error smaller than MaxError)
will be refined at the corresponding positions
in the original image (Image).
The runtime of matching depends on the parameter MaxError:
the larger the value the longer is the processing time,
because more points of the pattern have to be tested.
If MaxError is to low the pattern will not be found.
The value has therefore to be optimized for every
application.
NumLevel indicates the number of levels of the pyramid,
including the original image.
Optionally a second value can be given. This value specifies
the number (0..n) of the lowest level which is used the matching.
The region found up to this level will then be zoomed to the size
of the original level.
This can used to increase the runtime in the case that the accuracy
does not have to be so high.
Execution Information
- Multithreading type: reentrant (runs in parallel with non-exclusive operators).
- Multithreading scope: global (may be called from any thread).
- Automatically parallelized on tuple level.
Parameters
Image (input_object) singlechannelimage(-array) → object (byte)
Input image inside of which the pattern has to be found.
Matches (output_object) region(-array) → object
All points which have an error below a certain threshold.
TemplateID (input_control) template → (handle)
Template number.
MaxError (input_control) real → (real)
Maximal average difference of the gray values.
Default: 30.0
Suggested values: 0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 9.0, 11.0, 15.0, 17.0, 20.0, 30.0, 40.0, 50.0, 60.0, 70.0
Value range:
0
≤
MaxError
≤
255
Minimum increment: 1
Recommended increment: 3
NumLevel (input_control) integer(-array) → (integer)
Number of levels in the pyramid.
Default: 3
Suggested values: 1, 2, 3, 4, 5, 6, 7, 8
Result
If the parameter values are correct, the operator fast_match_mg
returns the value 2 (
H_MSG_TRUE)
.
If the input is empty (no input images are available) the behavior can
be set via set_system('no_object_result',<Result>).
If necessary, an exception is raised.
Possible Predecessors
create_template,
read_template,
adapt_template,
draw_region,
draw_rectangle1,
reduce_domain
Alternatives
best_match,
best_match_mg,
fast_match,
exhaustive_match,
exhaustive_match_mg
Module
Matching