Brightness-variation compensation method and coding/decoding apparatus for moving pictures

1. A moving image brightness variation compensation method for encoding digital moving images for transmission and storage, and for image processing when editing moving images, said moving image brightness variation compensation method comprising:

correcting a luminance value x of each pixel according to the formula D C ·x+D B , wherein D B is a parameter indicating a gain change and D C is a parameter indicating a contrast change, the parameters representing overall luminance changes between a reference image plane and an image plane being processed, and being determined by using differences in luminance values between corresponding pixels in the reference image plane and the image plane being processed.

2. A moving image brightness variation compensation method in accordance with claim 1 , wherein said image plane is an image frame or a video object plane.

3. A moving image coding apparatus, comprising:

parameter determining means for determining a parameter D B indicating a gain change and a parameter D C indicating a contrast change, the parameters representing overall luminance changes between a reference image plane and an image plane being processed, and being determined by using differences in luminance values between corresponding pixels in the reference image plane and the image plane being processed; and

brightness variation compensation means for correcting a luminance value x of each pixel in said image plane being processed using said parameters D B and D C according to the formula D C ·x+D B .

4. A moving image coding apparatus in accordance with claim 3 , wherein said image plane is an image frame or a video object plane.

5. A moving image decoding apparatus, comprising:

a brightness variation compensation means for correcting a luminance value χ of each pixel in a reconstructed image plane after decoding has been completed, using parameters D B and D C according to the formula D C ·x+D B , wherein:

the parameter D B indicates a gain change and the parameter D C indicates a contrast change, the parameters representing overall luminance changes between a reference image plane and an image plane being processed, and determined when an original image pane was being coded.

6. A moving image decoding apparatus in accordance with claim 5 , wherein said image plane is an image frame or a video object plane.

7. A computer-readable recording medium recording a moving image coding program, said moving image coding program containing instructions for a computer to execute:

a parameter determining step of determining a parameter D B indicating a gain change and a parameter D C indicating a contrast change, the parameters representing overall luminance changes between a reference image plane and an image plane being processed, and being determined by using differences in luminance values between corresponding pixels in the reference image plane and the image plane being processed; and

a brightness variation compensation step of correcting a luminance value x of each pixel in said image plane being processed using said parameters D B and D C according to the formula D C ·x+D B .

8. A computer-readable recording medium recording a moving image coding program in accordance with claim 7 , wherein said image plane is an image frame or a video object plane.

9. A computer-readable recording medium recording a moving image decoding program, said moving image decoding program containing instructions for a computer to execute:

a brightness variation compensation step of correcting a luminance value x of each pixel in a reconstructed image plane after decoding has been completed, using parameters D B and D C according to the formula D C ·x+D B wherein:

the parameter D B indicates a gain change and the parameter D C indicates a contrast change, the parameters representing overall luminance changes between a reference image plane and an image plane being processed, and determined when an original image plane was being coded.

10. A computer-readable recording medium recording a moving image decoding program in accordance with claim 9 , wherein said image plane is an image frame or a video object plane.

11. A computer-readable recording medium recording coded date of moving images, wherein said coded data includes a plurality of areas recording image plane coded data encoded by units of image planes, said areas recording image plane coded data comprising:

a parameter area recording parameters D B indicating gain changes and D C indicating contrast changes, the parameters representing overall luminance changes between reference image planes and an image planes being processed, and being determined by using differences in luminance values between corresponding pixels in the reference image plane and the image plane being processed; and

a coded area recording data in units of image planes relating to differences in pixel values for corresponding pixels between said reference image planes and image planes wherein luminance values χ of the pixels in said reference image planes have been corrected by using the parameters D B and D C according to the formula D C ·x+D B .

12. A computer-readable recording medium recording coded data of moving images in accordance with claim 11 , wherein said image plane is an image frame or a video object plane.