Two-dimensional image correlator

• US 4,651,297 A
• Filed: 11/28/1984
• Issued: 03/17/1987
• Est. Priority Date: 11/28/1984
• Status: Expired due to Term

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: General Dynamics
• Inventors: Schlunt, Richard S.
• Primary Examiner(s): Goldberg, E. A.
• Assistant Examiner(s): Reinhart, Mark
• Application Number:
  US06/676,026
• Time in Patent Office: 839 Days
• Field of Search: 364/822, 364/819, 364/820, 364/826, 364/827, 364/837, 364/851, 364/861, 343/9 PS, 350/162.13, 350/162.14
• US Class Current: 708/816
• CPC Class Codes: G06E 3/00 Devices not provided for in group G06E1/00, e.g. for processing analogue or hybrid data
• CPC Class Codes: G06V 10/88 Image or video recognition using optical means, e.g. reference filters, holographic masks, frequency domain filters or spatial domain filters

Abstract

The electro-optical correlator performs pattern-recognition by forming the columnar dot product of an input image with a reference image at video through-put rates. The correlator incorporates an analog-to-digital converter for digitizing the input-image data, a plurality of serially arranged delays having a delay time equivalent to one input-image data line, each delay for receiving in turn the digitized input data and for producing a parallel output signal, and a vertical column of photodiodes for receiving the respective multiple parallel delayed signals and for converting same to an optical output. The optical output is fed through a lens, reference image mask, and lens unit and is focused on a plurality of photodiodes that are connected to a time-delay-and-integrate (TDI) array. The data from the time- delay-and-integrate array are clocked through an analog-to- digital converter which produces the final system output. The time delay and integrate array may be a charge-coupled device (CCD).

Claims

1. A two-dimensional image correlator for correlating a reference image with an input image, comprising:

a first analog-to-digital converter having an input adapted to receive an analog scanning signal representative of lines of an input image and an output at which a corresponding digital scanning signal representative of lines of said input image is provided;

a series of digital storage and delay units each having an input and an output, the input of a first one of said units connected to said first analog-to-digital converter output, the output of each one of said units connected to an input of a next one of said units in said series of units wherein each unit receives in sequence as its input said digital scanning signal, stores a portion of said digital scanning signal corresponding to a line of said input image and provides a stored portion of said digital scanning signal at a unit output upon the receiving of a next portion corresponding to a next line of said digital scanning signal;

a plurality of digital-to-light converters positioned in a columnar orientation, each having an input and an output, the input of one of said digital-to-light converters connected to said first analog-to-digital converter output with the inputs of the other digital-to-light converters each respectively coupled to a different digital storage and delay unit output wherein each digital-to-light converter respectively converts the digital scanning signal received at its input into a point of light that is provided at its output, each point of light being of an intensity corresponding to the received digital scanning signal with the point of light;

an optically transmissive mask having a reference image recorded thereupon and oriented in rows and columns;

first optical means for diverging each point of light into a line of light for passing through a different row of said reference image;

second optical means for converging the line of light passing through each column of said reference image into a corresponding point of light;

a plurality of photo-sensitive cells positioned in a row orientation each having an input and an output, each cell input receiving at its input a different point of light from said second optical means and providing at its output a corresponding electrical cell signal representative of the intensity of the point of light received from said second optical means; and

time delay and integrating means for receiving, storing and integrating said cell signal and providing an output signal representative of the columnar dot product of the input image with the reference image.

2. The device of claim 1 further comprising a second analog-to-digital converter having an input connected to said time-delay and integrating means and an output wherein said second analog-to-digital converter receives said output signal, said output signal being the analog type, and an output at which a corresponding digital output signal is provided.

3. The device of claim 1 further comprising means for clocking said digital scanning signal as an output from said first analog-to-digital converter to said one of said digital-to-light converters and for clocking said digital scanning signal through said digital storage and delay units to said digital-to-light converters.

4. The device of claim 1 further comprising means for clocking said output signal as an output from said time delay and integrating means.

5. The device of claim 1 further comprising means for clocking said digital scanning signal as an output from said first analog-to-digital converter to said one of said digital-to-light converters, for clocking said digital scanning signal through said digital storage and delay units to said other digital to light converters, and for clocking said output signal as an output from said time delay and integrating means.

6. The device of claim 1 wherein said first optical means comprises a first cylindrical lens mounted between said digital-to-light converters and said optically transmissive mask, and said second optical means comprises a second cylindrical lens mounted between said optically transmissive mask and said photo-sensitive cells.

7. The device of claim 1 wherein said first optical means comprises a first plurality of optical fibers mounted between said digital-to-light converters and said optically transmissive mask, and said second optical means comprises a second plurality of optical fibers mounted between said optically transmissive mask and said photo-sensitive cells.

8. The device of claim 1 wherein the image correlation is performed at video through-put rates.

9. The device of claim 1 wherein the optically transmissive mask comprises a photo mask.