Moving picture processing method

1. A moving picture processing method for superimposing noise on a moving picture, said method comprising:

shifting a first noise which has been used for superimposition on a moving picture, in accordance with a motion of the moving picture;

superimposing the shifted first noise onto a moving picture that appears after the motion has occurred; and

specifying a superimposition area, on which noise is to be superimposed, in a current picture to be processed which is included in the moving picture,

wherein said shifting of the first noise includes

shifting the first noise in accordance with a motion of an image in the superimposition area, and

said superimposing of the shifted first noise includes

superimposing the shifted first noise onto the superimposition area.

2. The moving picture processing method according to claim 1 ,

wherein said specifying of the superimposition area includes

specifying the superimposition area based on frequency components in the current picture.

3. The moving picture processing method according to claim 1 ,

wherein said shifting of the first noise includes:

estimating the motion of the image in the superimposition area; and

shifting the first noise according to the estimated motion.

4. The moving picture processing method according to claim 1 , further comprising

obtaining a moving picture signal including the moving picture,

wherein said shifting of the first noise includes:

extracting, from the moving picture signal, motion information indicating the motion of the image in the superimposition area; and

shifting the first noise according to the motion indicated by the extracted motion information.

5. The moving picture processing method according to claim 4 ,

wherein the moving picture signal is coded,

said method further comprises

decoding the coded moving picture signal, and

said specifying of the superimposition area includes sequentially specifying the superimposition area in each of current pictures to be processed which is included in the decoded moving picture signal.

6. The moving picture processing method according to claim 5 ,

wherein the moving picture signal further includes first identification information indicating the superimposition area, and

said specifying of the superimposition area includes specifying the superimposition area based on the first identification information.

7. The moving picture processing method according to claim 5 ,

wherein the moving picture signal further includes second identification information indicating an area on which the first noise is to be superimposed within the superimposition area, and

said superimposing of the shifted first noise includes

superimposing the shifted first noise on the area indicated by the second identification information.

8. The moving picture processing method according to claim 5 ,

wherein the moving picture signal further includes an adjustment signal indicating the level of the noise to be superimposed, and

said superimposing of the shifted first noise includes

adjusting the first noise so that the level of the shifted first noise becomes equal to the level indicated by the adjustment signal, and superimposing the adjusted first noise on the superimposition area.

9. The moving picture processing method according to claim 1 , further comprising:

judging whether or not switching of image has occurred between the current picture included in the moving picture and a processed picture;

newly generating a second noise which has not been used for superimposition and superimposing the generated second noise on the current picture in the case where it is judged that the switching has occurred; and

superimposing the shifted first noise on the superimposition area in the case where it is judged that the switching has not occurred.

10. The moving picture processing method according to claim 9 ,

wherein said judging includes

generating the second noise and superimposing the generated second noise on the current picture in the case where it is judged that the switching has occurred, the second noise being of a type which is in accordance with a characteristic of the current picture.

11. The moving picture processing method according to claim 1 ,

wherein said superimposing of the shifted first noise includes

adjusting the level of the shifted first noise and superimposing the adjusted first noise on the superimposition area.

12. The moving picture processing method according to claim 11 ,

said adjusting of the level of the shifted first noise includes adjusting the level of the shifted first noise so that the higher the frequency components included in the superimposition area are, the higher the level of the shifted first noise becomes.

13. A moving picture processing apparatus which superimposes noise on a moving picture, said apparatus comprising:

a motion compensation unit operable to shift a first noise which has been used for superimposition on a moving picture, in accordance with a motion of the moving picture;

a superimposition unit operable to superimpose the shifted first noise onto a moving picture that appears after the motion has occurred; and

an area specification unit operable to specify a superimposition area, on which noise is to be superimposed, in a current picture to be processed which is included in the moving picture,

wherein said motion compensation unit is operable to shift the first noise in accordance with a motion of an image in the superimposition area, and

said superimposition unit is operable to superimpose the shifted first noise onto the superimposition area.

14. A non-transitory computer-readable medium having a program stored thereon for superimposing noise on a moving picture, the program causing a computer to execute:

shifting a first noise which has been used for superimposition on a moving picture, in accordance with a motion of the moving picture;

superimposing the shifted first noise onto a moving picture that appears after the motion has occurred; and

specifying a superimposition area, on which noise is to be superimposed, in a current picture to be processed which is included in the moving picture,

wherein the shifting of the first noise includes

shifting the first noise in accordance with a motion of an image in the superimposition area, and

the superimposing of the shifted first noise includes

superimposing the shifted first noise onto the superimposition area.

15. An integrated circuit which superimposes noise on one of moving pictures, said circuit comprising:

a motion compensation unit operable to shift a first noise which has been used for superimposition on a moving picture, in accordance with a motion of the moving picture;

a superimposition unit operable to superimpose the shifted first noise onto a moving picture that appears after the motion has occurred; and

an area specification unit operable to specify a superimposition area, on which noise is to be superimposed, in a current picture to be processed which is included in the moving picture,

wherein said motion compensation unit is operable to shift the first noise in accordance with a motion of an image in the superimposition area, and

said superimposition unit is operable to superimpose the shifted first noise onto the superimposition area.