Correlation detector for images

• US 5,189,712 A
• Filed: 07/17/1991
• Issued: 02/23/1993
• Est. Priority Date: 07/17/1990
• Status: Expired due to Term

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Tsutsumi, Kazumichi, Kajiwara, Yasuya
• Primary Examiner(s): Mancuso, Joseph
• Application Number:
  US07/731,605
• Time in Patent Office: 587 Days
• Field of Search: 382/42, 382/30, 382/34, 382/48, 364/724.12, 364/819, 364/820, 364/823, 364/824, 365/149
• US Class Current: 382/221
• CPC Class Codes: G06F 17/153 Multidimensional correlation or convolution
• CPC Class Codes: G06V 10/751 Comparing pixel values or logical combinations thereof, or feature values having positional relevance, e.g. template matching

Abstract

A correlation detector for images including: a unit for converting pixel signals of two images into digital data; a unit for deriving either an absolute value of a difference between the two pixel signals or a product of the two pixel signals from a table in accordance with pixel signal values of the two images; a unit for converting the derived value into an analog value; and a unit for storing electric charges while converting the converted analog value into a current value which is proportional to the converted analog value. Since the correlation between the two images are calculated using a table and the addition is performed in terms of storing electric charges, the correlation detector can be down-sized with simple circuits and its operation speed is improved as well.

Claims

1. A correlation detector for images, comprising:

means for converting a first plurality of pixel signals representing a first image and a second plurality of pixel signals representing a second image into digital data;

means for deriving one of (a) an absolute value of a difference between each pixel signal of said first plurality and a corresponding pixel signal of said second plurality, and (b) a product of each pixel signal of said first plurality and said corresponding pixel signal of said second plurality, from a table in accordance with pixel signal values of the pixel signals of said first plurality and said corresponding pixel signals of said second plurality;

means for converting said derived values into analog values; and

means for storing said analog values as electric charges by converting said analog values into current values proportional to said converted analog values, said storing means performing a mathematical summation operation on said analog values.

2. A detector as claimed in claim 1, wherein said deriving means comprises a read only memory storing said table.

3. A detector as claimed in claim 1, wherein said storing means comprises a capacitor.