Apparatus for detecting sudden changes of a feature in a region of an image that is divided into discrete picture elements

• US 4,747,150 A
• Filed: 05/21/1986
• Issued: 05/24/1988
• Est. Priority Date: 05/23/1985
• Status: Expired due to Term

• Current Assignee: ContextVision AB
• Original Assignee: ContextVision AB
• Inventors: Bigun, Josef, Knutsson, Hans, Granlund, Gosta
• Primary Examiner(s): Boudreau, Leo H.
• Assistant Examiner(s): Mancuso, Joseph
• Application Number:
  US06/865,341
• Time in Patent Office: 734 Days
• Field of Search: 382/50, 382/, 382/51, 382/41, 382/22, 382/21, 382/56
• US Class Current: 382/197
• CPC Class Codes: G06T 7/00 Image analysis

Abstract

The invention concerns an apparatus for detecting sudden changes of a feature in a region of an image that is divided into discrete picture elements, the feature being represented by complex valued signals, one for each picture element, the signal phase representing the feature class and the signal magnitude representing the certainty in the feature assertion. The apparatus includes a first unit (3) for providing the complex valued signals (10) within the region and at least a second unit for providing at least two collections of complex valued multiplication factor signals (11, 12, 13) that corresponds to the complex valued signals. The apparatus further has a third unit (4) for forming a measurement signal for each collection of multiplication factors, the measurement signal consisting of the sum of the squares of the magnitudes of a first sum signal, which consists of the complex valued products of the complex valued signals (10) and corresponding complex valued multiplication factor signals (11, 12, 13), and a second sum signal, which consists of the complex valued products of the complex valued signals and corresponding conjugate of the complex valued multiplication factor signals. A fourth unit (5) is provided for a complex valued coefficient weighted summation of a function, which depends on the complex valued multiplication factor signals, of the measurement signals from the third unit (4).

Claims

1. Apparatus comprising:

first means for recording a first image of a physical object or scene and dividing said first image into discrete picture elements;

second means for transforming said first image which has been divided into discrete picture elements into a vector representation, said vector representation comprising complex valued signals,

third means for accessing said complex valued signals from a plurality of picture elements which collectively form a plurality of overlapping regions of a vector valued image, one complex valued signal for each picture element of said plurality of picture elements, each of said complex valued signals having a phase which describes feature class and a magnitude which describes certainty in feature assertion, said complex valued signals representing said feature;

fourth means for accessing at least two collections of corresponding complex valued multiplication factor signals for each picture element of said plurality of picture elements, each of said complex valued multiplication factor signals having a phase and a magnitude, said at least two collections of corresponding complex valued multiplication factor signals forming at least two corresponding masks which represent a predetermined, idealized variation of said feature in a respective region of said plurality of overlapping regions;

fifth means coupled to said third means and said fourth means for correlating said complex valued image signals, for each region of said plurality of overlapping regions, to said at least two collections of said corresponding complex valued multiplication factor signals of a respective region, so that at least two measurement signals are outputted by said third means for each region of said plurality of overlapping regions; and

,

sixth means coupled to said fifth means and inputting said at least two signals for norming and summing said at least two measurement signals so that a complex valued output signal is outputted by said sixth means for each region of said plurality of overlapping regions thereby producing a second image representing characterizing properties of a recorded image of said physical object or scene.

2. Apparatus according to claim 1 wherein said fifth means includes a plurality of correlating units, one each for correlating one of said at least two collections of said corresponding complex valued multiplication factor signals to said complex valued signals so that one measurement signal for each collection is outputted by a respective correlating unit.

3. Apparatus according to claim 2 wherein each of said correlating units comprises a first adder coupled to a first cosine generator and a first sine generator, said first cosine generator being coupled to a first multiplying summator which is coupled to a first squaring unit, and said first sine generator being coupled to a second multiplying summator which is coupled to a second squaring unit, a second adder coupled to a second cosine generator and a second sine generator, said second cosine generator being coupled to a third multiplying summator which is coupled to a third squaring unit, and said second sine generator being coupled to a fourth multiplying summator which is coupled to a fourth squaring unit, a first multiplicator coupled to said first, second, third and fourth multiplying summators, and a third adder being coupled to said first, second, third and fourth squaring units, the magnitude of said complex valued signals and the magnitude of said complex valued multiplication factor signals being fed to said first multiplicator and a resulting magnitude product signal being outputted from said first multiplicator to said first, second, third and fourth multiplying summators, the phase of said complex valued signals and the phase of said complex valued multiplication factor signals being fed to said first adder for adding and to said second adder for subtracting, the resulting phase signal of said first adder being outputted to said first cosine generator and said first sine generator, so that a first cosine value is fed from said first cosine generator to said first multiplying summator for multiplying by said resulting magnitude product signal to generate a first product sum which is fed to said first squaring unit for squaring and inputted to said third adder, and so that a first sine value is fed from said first sine generator to said second multiplying summator for multiplying by said resulting magnitude product signal to generate a second product sum which is fed to said second squaring unit for squaring and inputted to said third adder, the resulting phase signal of said second adder being outputted to said second cosine generator and said second sine generator, so that a second cosine value is fed from said second cosine generator to said third multiplying summator for multiplying by said resulting magnitude product signal to generate a third product sum which is fed to said third squaring unit for squaring and inputted to said third adder, and so that a second sine value is fed from said second sine generator to said fourth multiplying summator for multiplying by said resulting magnitude product signal to generate a fourth product sum which is fed to said fourth squaring unit for squaring and inputted to said fourth adder, said signals inputted to said third adder being combined in said third adder to generate one of said at least two measurement signals.

4. Apparatus according to claim 2 wherein said sixth means comprises a plurality of function generators, one each for each correlatint unit, each of said function generators being coupled to a corresponding weighting means, each of said weighting means being coupled to a first adder and a second adder, and wherein said measurement signals outputted by respective of said correlating units are inputted by respective of said function generators, each respective function generator outputting a respective function signal to a respective of said weighting means, each respective of said function signals being weighted with a respective predetermined complex valued signal thereby being transformed by each respective of said weighting means from polar to rectangular representation, the real part of said rectangular representation being outputted to said first adder and the imaginary part of said rectangular representation being outputted to said second adder, said first adder outputting a real part of said complex valued output signal and said second adder outputting the imaginary part of said complex valued output signal.

5. Apparatus according to claim 2 wherein each of said correlating units comprises a first multiplicator coupled to one input of a first adder and one input of a second adder, a second multiplicator coupled to a sign inverting input of said first adder and another input of said second adder, a third multiplicator coupled to one input of a third adder and a sign inverting input of a fourth adder, and a fourth multiplicator coupled to another input of said third adder and one input of said fourth adder, said first, second, third and fourth adders being coupled to a first, second, third and fourth summator, respectively, which are coupled to a fifth, sixth, seventh and eighth multiplicator, respectively, which are coupled to a fifth adder, and wherein real parts of said complex valued signals and real parts of said complex valued multiplication factor signals are received by said first multiplicator to be multiplied and outputted to said one input of said first adder and said another input of said second adder as first output signals, imaginary parts of said complex valued signals and imaginary parts of said complex valued multiplication factor signals are received by said second multiplicator to be multiplied and outputted to said sign inverting input of said first adder and said one input of said second adder as second output signals, real parts of said complex valued signals and imaginary parts of said complex valued multiplication factor signals are received by said third multiplicator to be multiplied and outputted to said one input of said third adder and said sign inverting input of said fourth adder as third output signals, and imaginary parts of said complex valued signals and real parts of said complex valued multiplication factor signals are received by said fourth multiplicator to be multiplied and outputted to said another input of said third adder and said one input of said fourth adder as fourth output signals, said first adder forming the real parts of said first and second output signals, said real parts of said first and second output signals being outputted to said first summator for adding, the resulting first sum signals being outputted from said first summator to said fifth multiplicator for squaring, and first squared sum signals being outputted from said fifth multiplicator to said fifth adder, said second adder forming the imaginary parts of said first and second output signals, said imaginary parts of said first and second output signals being outputted to said second summator for adding, the resulting second sum signals being outputted from said second summator to said sixth multiplicator for squaring, and second squared sum signals being outputted from said sixth multiplicator to said fifth adder, said third adder forming the real parts of said third and fourth output signals, said real parts of said third and fourth output signals being outputted to said third summator for adding, the resulting third sum signals being outputted from said third summator to said seventh multiplicator for squaring, and third squared sum signals being outputted from said seventh multiplicator to said fifth adder, and said fourth adder forming the imaginary parts of said third and fourth output signals, said imaginary parts of said third and fourth output signals being outputted to said fourth summator for adding, the resulting fourth sum signals being outputted from said fourth summator to said eighth multiplicator for squaring, and fourth squared sum signals being ouputted from said said eighth multiplicator to said fifth adder, said first, second, third and fourth squared sum signals being combined in said fifth adder to generate one of said at least two measurement signals.

6. Apparatus according to claim 2 wherein each of said correlating units comprises a first implementing means for receiving and processing signals and coupled to a first summator, which is coupled to one input of a first adder and one input of a second adder, said first and second adders being coupled to a first and second squaring unit, respectively, which are coupled to a third adder;

a second implementing means for receiving and processing signals and coupled to a second summator, which is coupled to a sign inverting input of said first adder and another input of said second adder;

a third implementing means for receiving and processing signals and coupled to a third summator, which is coupled to one input of a fourth adder and one input of a fifth adder, said fourth and fifth adders being coupled to a third and fourth squaring unit, respectively, which are coupled to said third adder; and

, a fourth implementing means for receiving and processing signals and coupled to a fourth summator, which is coupled to a sign inverting input of said fourth adder and another input of said fifth adder; and

wherein real parts of said complex valued signals are received by said first and fourth implementing means and imaginary parts of said complex valued signals are received by said second and third implementing means, said first and fourth implementing means multiplying said real parts of said complex valued signals, respectively, by corresponding real parts of said complex valued multiplication factor signals and imaginary parts of said complex valued multiplication factor signals, respectively, to produce first and second output signals, respectively, which are fed to said first and fourth summators, respectively, which sum said first and second ouput signals, respectively, and generate a first and second intermediate sum signal, respectively, said second and third implementing means multiplying said imaginary parts of said complex valued signals, respectively, by corresponding imaginary parts of said complex valued multiplication factor signals and real parts of said complex valued multiplication factor signals, respectively, to produce third and fourth output signals, respectively, which are fed to said second and third summators, respectively, which sum said third and fourth output signals, respectively, and generate a third and fourth intermediate sum signal, respectively said first intermediate sum signal being fed to said one input of said first adder and said third intermediate sum signal being fed to said sign inverting input of said first adder, said first adder summing said first and third intermediate sum signals and generating a first sum signal which is outputted to said first squaring unit for squaring, and a first squared sum signal being outputted from said first squaring unit to said third adder, said first intermediate sum signal also being fed to said one input of said second adder and said third intermediate sum signal also being fed to said another input of said second adder, said second adder summing said first and third intermediate sum signals and generating a second sum signal which is outputted to said second squaring unit for squaring, and a second squared sum signal being outputted from said second squaring unit to said third adder, said fourth intermediate sum signal being fed to said one input of said fourth adder and said second intermediate sum signal being fed to said sign inverting signal of said fourth adder, said fourth adder summing said fourth and second intermediate sum signals and generating a third sum signal which is outputted to said third squaring unit for squaring, and a third squared sum signal being outputted from said third squaring unit to said third adder, and said fourth intermediate sum signal also being fed to said one input of said fifth adder and said second intermediate sum signal also being fed to said another input of said fifth adder, said fifth adder summing said fourth and second intermediate sum signals and generating a fourth sum signal which is outputted to said fourth squaring unit for squaring, and a fourth squared sum signal being outputted from said fourth squaring unit to said third adder, said first, second, third and fourth squared sum signals being combined in said third adder to generate one of said at least two measurement signals.

7. Apparatus of claim 1 wherein said fourth means is for accessing four collections of corresponding complex valued multiplication factor signals for each discrete picture element in said collection.