fast_match — Searching all good matches of a template and an image.
fast_match is obsolete and is only provided for
reasons of backward compatibility. New applications should use the
shape-based or NCC-based operators instead.
fast_match performs a matching of the
Hereby the template will be moved over the points of
Image so that the template always lies completely
The matching criterion (“displaced frame difference”)
is defined as follows:
The difference between
is that the matching for one position is stopped if the error
is to high. This leads to a reduced runtime but one might
miss correct matches.
The runtime of the operator depends mainly on the size of the domain
Therefore it is important to restrict the domain as far as possible,
i.e. to apply the operator only in a very confined “region of interest”.
MaxError determines the maximal error which the
searched position is allowed to show.
The lower this value is, the faster the operator runs.
All points which show a matching error smaller than
MaxError will be returned in the output region
This region can be used for further processing. For example by
using a connection and
best_match to find all the
matching objects. If no point has a match error below
the empty region (i.e no points) is returned.
Input image inside of which the pattern has to be found.
All points whose error lies below a certain threshold.
Maximal average difference of the gray values.
Default value: 20.0
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
Typical range of values:
Minimum increment: 1
Recommended increment: 1
If the parameter values are correct, the operator
returns the value 2 (H_MSG_TRUE).
If the input is empty (no input images are available) the behavior can
be set via
If necessary, an exception is raised.