Multiscale feature detector using filter banks

• US 6,064,768 A
• Filed: 06/30/1997
• Issued: 05/16/2000
• Est. Priority Date: 07/29/1996
• Status: Expired due to Term

• Current Assignee: Wisconsin Alumni Research Foundation (University of Wisconsin System)
• Original Assignee: Wisconsin Alumni Research Foundation (University of Wisconsin System)
• Inventors: Hajj, Hazem M., Chin, Roland T., Nguyen, Truong Q.
• Primary Examiner(s): Boudreau, Leo H.
• Assistant Examiner(s): Mariam, Daniel G.
• Application Number:
  US08/884,760
• Time in Patent Office: 1,051 Days
• Field of Search: 382/190, 382/195, 382/260, 382/275, 382/318, 382/189, 382/278, 364/724.2, 364/728.03
• US Class Current: 382/195
• CPC Class Codes: G06T 5/20 using local operators
• CPC Class Codes: G06V 10/443 by matching or filtering

Abstract

A detector system locates a feature in an input signal. The input signal is applied to a multiscale filter bank which produces a corresponding set of filtered signals that are applied to a multiscale detector. A scale space tree table is produced by the detector which indicates the location in each filtered signal where the feature is possibly located. A MAP correlator examines the scale space tree table to determine which indications therein are feature locations. One-dimensional and two-dimensional embodiments are described. In addition, the design framework is disclosed for extending a one scale filter to a multiscale filter, for designing a filter bank from the multiscale filter and for designing the MAP correlator dependent on the feature being located and the chosen filter bank.

Claims

1. A detector system for locating a feature in an input signal, the combination comprising:

a multiscale filter which applies a filter operator to the input signal to produce a plurality of filtered output signals at a corresponding plurality of scales;

a multiscale detector which receives the filtered output signals and produces a table which indicates the possible locations in the input signal of the detected feature therein; and

a MAP correlator which examines the table and correlates the values therein at each indicated feature location with a model response, said MAP correlator producing an output signal indicating the location of the feature if the correlation exceeds a preset threshold.

2. The detector system as recited in claim 1 in which the input signal is a two-dimensional image and the output signals form a bit map.

3. The detector system as recited in claim 1 in which the multiscale detector includes a feature signature generator which produces the table by forming a scale space tree from the corresponding locations in each filtered output signal at which the feature is detected.

4. The detector system as recited in claim 1 in which the multiscale filter is a filter bank comprised of a set of series connected filter stages.

5. The detector system as recited in claim 4 in which each filter stage includes a convolver which receives the input signal and convolves it with a filter kernel, and in which the first filter bank stage employs a filter kernel H₁ and the remaining filter bank stages employ a filter kernel H₀.

6. The detector system as recited in claim 1 in which the input signal is a series of two-dimensional images and the output signals form a series of bit maps.