IMAGE CORRECTION CIRCUIT, IMAGE CORRECTION METHOD AND IMAGE DISPLAY

• US 20070286532A1
• Filed: 05/02/2007
• Published: 12/13/2007
• Est. Priority Date: 05/17/2006
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: HARADA, Shigeru
• Granted Patent: US 8,369,645 B2
• Time in Patent Office: Days
• US Class Current: 382/309
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 5/40 using histogram techniques
• CPC Class Codes: G06T 5/92 based on global image properties
• CPC Class Codes: H04N 5/202 Gamma control circuits for controlling camera response irrespective of the scene brightness H04N23/82
• CPC Class Codes: H04N 5/208 for compensating for attenuation of high frequency components, e.g. crispening, aperture distortion correction
• CPC Class Codes: H04N 5/775 between a recording apparatus and a television receiver

Abstract

An image correction circuit includes: a region determining means for determining an intermediate luminance region in each image frame on the basis of the description of input image data; a luminance distribution acquiring means for acquiring a luminance distribution of input image data in the determined intermediate luminance region in each image frame; a determining means for determining an input/output characteristic line in each image frame by adaptively changing a predetermined reference input/output characteristic line on the basis of the acquired luminance distribution of the intermediate luminance region, the input/output characteristic line defining the substance of image correction on input image data; and a correction executing means for executing image correction on input image data on the basis of the determined input/output characteristic line.

Claims

1. An image correction circuit comprising:

a region determining means for determining an intermediate luminance region in each image frame on the basis of the descriptions of input image data;

a luminance distribution acquiring means for acquiring a luminance distribution of input image data in the determined intermediate luminance region in each image frame;

a determining means for determining an input/output characteristic line in each image frame by adaptively changing a predetermined reference input/output characteristic line on the basis of the acquired luminance distribution of the intermediate luminance region, the input/output characteristic line defining the substance of image correction on input image data; and

a correction executing means for executing image correction on input image data on the basis of the determined input/output characteristic line.

2. The image correction circuit according to claim 1, wherein

the region determining means determines a weighed luminance center of a luminance distribution of input image data in each image frame, and determines an area as the intermediate luminance region, the area determined by setting a first width from the acquired weighed luminance center to a low luminance side by setting a second width from the weighed luminance center to a high luminance side.

3. The image correction circuit according to claim 1, wherein

the luminance distribution acquiring means acquires a black-side intermediate luminance distribution in each image frame as a luminance distribution in a region between a lowest luminance in the determined intermediate luminance region and a reference luminance provided in the center of the intermediate luminance region,

the determining means determines a low-luminance-region input/output characteristic curve on the basis of the acquired black-side intermediate luminance distribution, the low-luminance-region input/output characteristic curve passing through a reference point, in the reference input/output characteristic line, determined in accordance with the reference luminance and through a minimum luminance point of the reference input/output characteristic line, and

the correction executing means executes image correction on input image data having a luminance side which is lower than the reference luminance on the basis of the determined low-luminance-region input/output characteristic curve.

4. The image correction circuit according to claim 3, wherein

the low-luminance-region input/output characteristic curve is a curve provided below the reference input/output characteristic line and not 44 having an inflection point.

5. The image correction circuit according to claim 3, wherein

the luminance distribution acquiring means further acquires a black-side luminance distribution as a luminance distribution in a region of lower luminance relative to the lowest luminance in the intermediate luminance region, and

the determining means determines the low-luminance-region input/output characteristic curve on the basis of the acquired black-side luminance distribution as well as the black-side intermediate luminance distribution.

6. The image correction circuit according to claim 3, wherein

the luminance distribution acquiring means further acquires a white-side intermediate luminance distribution as a luminance distribution in a region between a highest luminance in the determined intermediate luminance region and the reference luminance,

the determining means further determines a high-luminance-region input/output characteristic curve passing through the reference point in the reference input/output characteristic line, and through a maximum luminance point of the reference input/output characteristic line on the basis of the acquired white-side intermediate luminance distribution, and

the correction executing means executes image correction on input image data in regions of lower luminance and higher luminance relative to the reference luminance on the basis of the determined low-luminance-region input/output characteristic curve and the determined high-luminance-region input/output characteristic curve, respectively.

7. The image correction circuit according to claim 6, wherein

the high-luminance-region input/output characteristic curve is a curve provided above the reference input/output characteristic line and not having an inflection point.

8. The image correction circuit according to claim 6, wherein

the luminance distribution acquiring means further acquires a white-side luminance distribution as a luminance distribution in a region of higher luminance relative to the highest luminance in the intermediate luminance region, and

the determining means determines the high-luminance-region input/output characteristic curve on the basis of the acquired white-side luminance distribution as well as the white-side intermediate luminance distribution.

9. The image correction circuit according to claim 1, wherein

the luminance distribution acquiring means acquires a white-side intermediate luminance distribution in each image frame as a luminance distribution in a region between a highest luminance in the determined intermediate luminance region and a reference luminance provided in the center of the intermediate luminance region,

the determining means determines a high-luminance-region input/output characteristic curve on the basis of the acquired white-side intermediate luminance distribution, the high-luminance-region input/output characteristic line passing through a reference point, in the reference input/output characteristic line, determined in accordance with the reference luminance and through a maximum luminance point of the reference input/output characteristic line, and

the correction executing means executes image correction on input image data having a luminance which is higher than the reference luminance on the basis of the determined high-luminance-region input/output characteristic curve.

10. An image correction method comprising the steps of:

determining an intermediate luminance region in each image frame on the basis of the descriptions of input image data;

acquiring a luminance distribution of input image data in the determined intermediate luminance region in each image frame;

determining an input/output characteristic line in each image frame by adaptively changing a predetermined reference input/output characteristic line on the basis of the acquired luminance distribution of the intermediate luminance region, the input/output characteristic line defining the substance of image correction on input image data; and

executing image correction on input image data on the basis of the determined input/output characteristic line.

11. An image display comprising:

a region determining means for determining an intermediate luminance region in each image frame on the basis of the descriptions of input image data;

a luminance distribution acquiring means for acquiring a luminance distribution of input image data in the determined intermediate luminance region in each image frame;

a determining means for determining an input/output characteristic line in each image frame by adaptively changing a predetermined reference input/output characteristic line on the basis of the acquired luminance distribution of the intermediate luminance region, the input/output characteristic line defining the substance of image correction on input image data;

a correction executing means for executing image correction on input image data on the basis of the determined input/output characteristic line, and

a display means for displaying an image on the basis of input image data on which image correction is performed.

12. An image correction circuit comprising:

a region determining section determining an intermediate luminance region in each image frame on the basis of the descriptions of input image data;

a luminance distribution acquiring section acquiring a luminance distribution of input image data in the determined intermediate luminance region in each image frame;

a determining section determining an input/output characteristic line in each image frame by adaptively changing a predetermined reference input/output characteristic line on the basis of the acquired luminance distribution of the intermediate luminance region, the input/output characteristic line defining the substance of image correction on input image data; and

a correction executing section executing image correction on input image data on the basis of the determined input/output characteristic line.

13. An image display comprising:

a region determining section determining an intermediate luminance region in each image frame on the basis of the descriptions of input image data;

a luminance distribution acquiring section acquiring a luminance distribution of input image data in the determined intermediate luminance region in each image frame;

a determining section determining an input/output characteristic line in each image frame by adaptively changing a predetermined reference input/output characteristic line on the basis of the acquired luminance distribution of the intermediate luminance region, the input/output characteristic line defining the substance of image correction on input image data;

a correction executing section executing image correction on input image data on the basis of the determined input/output characteristic line, and

a display section displaying an image on the basis of input image data on which image correction is performed.