Motion detection of an input image signal during a current period with respect to a restored image signal in a previous period

• US 6,246,780 B1
• Filed: 07/25/1996
• Issued: 06/12/2001
• Est. Priority Date: 07/31/1995
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Sato, Makoto
• Primary Examiner(s): PATEL, JAYANTI K
• Application Number:
  US08/687,185
• Time in Patent Office: 1,783 Days
• Field of Search: 382/236, 382/237-238, 382/264, 382/107, 382/299, 382/251, 382/275, 348/402, 348/407, 348/413, 345/141, 345/87, 358/521
• US Class Current: 382/107
• CPC Class Codes: G06T 5/20 using local operators
• CPC Class Codes: G06T 7/254 involving subtraction of images

Abstract

An image processor in which an input image signal having a number L₁ of gradation levels is converted into an image signal having a number L₂ (<L₁) of gradation levels, and the converted image signal is stored. The stored image signal is used to restore the original image signal, and motion of an image is detected on the basis of an image signal input in the current period and the restored image signal in the previous period.

Claims

1. An image processing apparatus comprising:

a) input means for inputting a first image signal having a number L1 of gradation levels;

b) first conversion means for converting the first image signal into a second image signal having a number L2 (<

L1) of gradation levels;

c) storage means for storing the second image signal;

d) second conversion means for converting the second image signal into a third image signal which is restored to an image signal as it was before a conversion processing by said first conversion means said first conversion means minimizes a predetermined distortion function upon converting the number of gradation levels;

e) detection means for detecting a motion of the first image signal input by said input means on a basis of the third image signal output from said second conversion means; and

f) control means for reading out from said storage means the second image signal corresponding to the first image signal whose motion is detected by said detection means, and supplying the read-out second image signal to display means.

2. An apparatus according to claim 1, wherein said display means displays an image on a basis of the second image signal supplied by said control means.

3. An apparatus according to claim 2, wherein said display means comprises a ferroelectric liquid crystal display.

4. An apparatus according to claim 1, wherein said second conversion means performs filter processing having low-pass characteristics by performing a product-sum operation of a predetermined weighing value and the second image signal.

5. An apparatus according to claim 1, wherein

said first conversion means minimizes a predetermined distortion function upon converting the number of gradation levels,

said second conversion means converts the second image signal into the third image signal on a basis of a parameter of the distortion function, and

said detection means detects a motion between successive frames by comparing the first image signal and the third image signal.

6. An apparatus according to claim 5, wherein the distortion function minimizes a square error between the first image signal subjected to the product-sum operation with a predetermined coefficient and the second image signal.

7. An apparatus according to claim 5, wherein said first conversion means comprises:

a) first product-sum operation means for performing product-sum operation processing of a plurality of pixels in a predetermined area of the first image signal and a predetermined input weighing value;

b) second product-sum operation means for performing product-sum operation processing of a plurality of pixels in a predetermined area of the second image signal and a predetermined output weight value; and

c) nonlinear processing means for receiving operation results from said first and second product-sum operation means and determined output data on a basis of predetermined nonlinear characteristics.

8. An image processing apparatus comprising:

a) input means for inputting a first image signal having a number L1 of gradation levels;

b) first conversion means for converting the first image signal into a second image signal having a number L2 (<

L1) of gradation levels;

c) storage means for storing the second image signal;

d) second conversion means for converting the second image signal into a third image signal having a number L1 of gradation levels;

e) detection means for detecting a motion of the first image signal of one picture on a basis of the third image signal of another picture; and

f) output means for outputting the second image signal from said storage means in accordance with the output of said detection means, wherein

said first conversion means minimizes a predetermined distortion function upon converting the number of gradation levels,

said second conversion means converts the second image signal into the third image signal on a basis of a parameter of the distortion function, and

said detection means detects a motion between successive frames by comparing the first image signal and the third image signal.

9. An apparatus according to claim 8, wherein the distortion function minimizes a square error between the first image signal subjected to the product-sum operation with a predetermined coefficient and the second image signal.

10. An apparatus according to claim 8, wherein said first conversion means comprises:

a) first product-sum operation means for performing product-sum operation processing of a plurality of pixels in a predetermined area of the first image signal and a predetermined input weighing value;

b) second product-sum operation means for performing product-sum operation processing of a plurality of pixels in a predetermined area of the second image signal and a predetermined output weight value; and

c) nonlinear processing means for receiving operation results from said first and second product-sum operation means and determined output data on the basis of predetermined nonlinear characteristics.

11. An image processing method comprising the steps of:

inputting a first image signal having a number L1 of gradation levels;

converting the first image signal into a second image signal having a number L2 (<

L1) of gradation levels;

storing the second image signal in a storage medium;

converting the second image signal into a third image signal which is restored to an image signal as it was before a conversion processing in said converting step of the first image signal the first converting step of the first image signal includes a step of minimizing a predetermined distortion function upon converting the number of gradation levels;

detecting a motion of the first image signal input in said inputting step on a basis of the third image signal output in said converting step of the second image signal; and

reading out from said storage medium the second image signal corresponding to the first image signal whose motion is detected in said detection step, and supplying the read-out second image signal to display means.

12. An image processing method comprising:

a) an input step of inputting a first image signal having a number L1 of gradation levels;

b) a first conversion step of converting the first image signal into a second image signal having a number L2 (<

L1) of gradation levels;

c) a storing step of storing the second image signal in a storage means;

d) a second conversion step of converting the second image signal into a third image signal having a number L1 of gradation levels;

e) a detection step of detecting a motion of the first image signal of one picture on a basis of the third image signal of another picture; and

f) an output step of outputting the second image signal from said storage means in accordance with the output of said detection step, wherein

said first conversion step includes a step of minimizing a predetermined distortion function upon converting the number of gradation levels,

said second conversion step includes a step of converting the second image signal into the third image signal on a basis of a parameter of the distortion function, and

said detection step includes a step of detecting a motion between successive frames by comparing the first image signal and the third image signal.