Bidimensional correlation device

• US 4,449,193 A
• Filed: 04/23/1981
• Issued: 05/15/1984
• Est. Priority Date: 04/25/1980
• Status: Expired due to Fees

• Current Assignee: Thomson-CSF (Thales SA)
• Original Assignee: Thomson-CSF (Thales SA)
• Inventors: Tournois, Pierre
• Primary Examiner(s): Gruber, Felix D.
• Application Number:
  US06/256,929
• Time in Patent Office: 1,118 Days
• Field of Search: 364/604, 364/728, 364/821, 364/861, 382/32, 382/34, 382/42, 343/5 MM
• US Class Current: 382/278
• CPC Class Codes: G06G 7/1928 for forming correlation integrals; for forming convolution integrals G06G7/195, G06G7/1907 and G06G7/1914 take precedence

Abstract

A device which provides bidimensional correlation of an image obtained by the scanning of electromagnetic or acoustic waves of the reference image. The scanned image and the reference image are written into memories with a pair of memories storing the real and imaginary portion of the signal of the corresponding images. After analog conversion, the signals are placed on a carrier and correlated in a line-by-line manner through the use and elastic wave convolver. The output of the convolver is demodulated with a correlation signal being applied to an adder and the correlation image being stored with its real and imaginary portions in a set of memories to provide a bidimensional correlation of an image.

Claims

1. A device for the bidimensional correlation between a reference image of a plane Oxy having lines oriented in the Ox direction and a scanned image obtained by scanning in the plane Oxy, the scanned lines being parallel to Ox, wherein said device comprises:

a correlation means including a surface wave convolver said correlation means connected to receive first signals corresponding to said reference image and second signals corresponding to said scanned image with said reference image being formed from K lines of M points and said scanned image being formed from L lines of N points, in which L>

K and N<

M, wherein the K lines of the reference image are correlated line-by-line with all the systems of K lines such as i at i+k-1 of the scanned image in which 1 is less than or equal to i less than or equal to L minus K, whereby one line of the reference image is simultaneously inputted with one line of the scanned image in order to supply to said correlation means an electrical representation of a monodimensional correlation line formed from points corresponding to the displacement of said reference image and said scanned image thus supplying after summation for a same displacement α

along Ox, (L-K) correlation lines of (M-N) points, wherein said first signals corresponding to the reference image are stored in a first pair of random access memories and said second signals corresponding to the scanned image are each stored in a second pair of random access memories which are read under the control of a clock with one of said first and second signals being read along Ox and the other of said first and second signals being read in the opposite direction along Ox;

digital to analog converter means connected to said random access memories for receiving the output of said random access memories;

modulation means for receiving the output of said digital-to-analog converter means and supplying a modulated signal placed on a frequency carrier f_O to said correlation means;

demodulation means for demodulating the output of said correlation means and applying said demodulated signal to an analog-digital converter;

adder means which adds the output of said analog to digital converter and which thereby adds the signals for the points corresponding to one and the same displacement for said (M-N) monodimensional correlation lines of said reference image and said scanned image with the output of said adder means supplying a bidimensional correlation signal whereby said device for bidimensional correlation supplies a new bidimensional correlation line after each new scanned line of the image obtained by scanning.

2. A device for the bidimensional correlation between a reference image which is formed in a plane having lines oriented in the x direction and a scanned image obtained by scanning in the plane with the obtained scanned lines being parallel to the x direction, wherein said device comprises:

modulation means for receiving an electrical indication of said reference image and said scanning image in order to output a modulated signal;

correlation means including a surface wave convolver connected to the output of said modulation means wherein a portion of said modulated signal corresponds to a scanned line of said scanned image and a corresponding line of said reference image in order to provide from said correlation means an output in the form of a monodimensional correlation line formed from the displacement of said reference image and said scanned image;

demodulation means connected to the output of said correlation means for demodulating the output of said correlation means; and

adder means which receives the output of said demodulation means thereby adding the signals for the points corresponding to the displacement for each of said monodimensional correlation lines of said reference and scanned images with the output of said adder means supplying a bidimensional correlation signal so that said device for bidimensional correlation supplies a new bidimensional correlation line after each new scanned line of the image obtained by scanning.

3. A bidimensional correlation device according to claim 2, wherein said convolver is of the charge transfer type.

4. A bidimensional correlation device according to claim 3, wherein the reference image is formed from K lines of M points and the scanned image is formed from L lines of N points, in which L>

K and N<

M, the K lines of the reference image are correlated line by line with all the systems of K lines such as i at i+K-1 of the scanned image in which 1≦

i≦

L-K, thus supplying after summation for a same displacement l along Ox, (L-K) correlation lines of (M-N) points.

5. A bidimensional correlation device according to claim 4, wherein said reference and scanned images have complex components and wherein said bidimensional correlation device further comprises two pairs of memories for storing electrical indications of the complex components of the reference and the scanned image.

6. A bidimensional correlation device according to claim 5, wherein said memories are constituted by charge transfer devices.