IMAGE PROCESSING APPARATUS AND IMAGE PROCESSING METHOD

• US 20130177206A1
• Filed: 12/12/2012
• Published: 07/11/2013
• Est. Priority Date: 01/06/2012
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Hata, Tetsuya
• Granted Patent: US 9,025,820 B2
• Time in Patent Office: Days
• US Class Current: 382/103
• CPC Class Codes: H04N 23/12 with one sensor only
• CPC Class Codes: H04N 23/80 Camera processing pipelines; Components thereof
• CPC Class Codes: H04N 23/86 for controlling the colour saturation of colour signals, e.g. automatic chroma control circuits
• CPC Class Codes: H04N 23/88 for colour balance, e.g. white-balance circuits or colour temperature control
• CPC Class Codes: H04N 9/68 for controlling the amplitude of colour signals, e.g. automatic chroma control circuits H04N9/71, H04N9/73 take precedence; camera processing pipelines for controlling the colour saturation of colour signals H04N23/86

Abstract

An image processing apparatus includes: an image processing unit that executes image processing on an input image; a point light source detection unit that detects a point light source included in the input image; a scene determination unit that determines whether or not the input image shows a vivid scene based on a detection result of the point light source detection unit and an image signal of the input image; and a control unit that controls the image processing unit to change image processing for the input image in accordance with a determination result of the scene determination unit.

Claims

1. An image processing apparatus comprising:

an image processing unit that executes image processing on an input image;

a point light source detection unit that detects a point light source included in the input image;

a scene determination unit that determines whether or not the input image shows a vivid scene based on a detection result of the point light source detection unit and an image signal of the input image; and

a control unit that controls the image processing unit to change image processing for the input image in accordance with a determination result of the scene determination unit.

2. The image processing apparatus according to claim 1, wherein

the point light source detection unit detects whether or not the input image includes a point light source using at least one of a photometry result obtained with respect to a captured scene, a luminance signal of the input image, and an edge signal extracted from the input image.

3. The image processing apparatus according to claim 1, wherein

when the point light source detection unit has detected a point light source, the scene determination unit determines whether or not a region corresponding to the point light source in the input image shows a vivid scene.

4. The image processing apparatus according to claim 3, wherein

the region corresponding to the point light source is a region composed of pixels that have a luminance value equal to or greater than a predetermined threshold value in the input image.

5. The image processing apparatus according to claim 3, wherein

the point light source detection unit divides the input image into a plurality of small areas and determines whether or not each small area includes a point light source.

6. The image processing apparatus according to claim 5, wherein

the point light source detection unit compares photometric values of the small areas with one another, and determines that a point light source has been detected when any of the small areas has a higher photometric value than peripheral small areas and an average of the photometric values of the small areas is smaller than a predetermined threshold value.

7. The image processing apparatus according to claim 5, wherein

the point light source detection unit calculates the number of small areas that have a higher photometric value than peripheral small areas based on photometric values of the small areas, and determines that a point light source has been detected when the calculated number is equal to or greater than a predetermined threshold value.

8. The image processing apparatus according to claim 1, wherein

the scene determination unit determines that the input image shows a vivid scene when chroma of the input image is higher than a predetermined scene determination threshold value, and sets the scene determination threshold value low when the point light source detection unit has detected a point light source.

9. The image processing apparatus according to claim 1, wherein

the point light source detection unit outputs information on a degree to which the point light source detected from the input image occupies the input image, and the scene determination unit determines whether or not the input image shows a vivid scene based on the information on the degree.

10. The image processing apparatus according to claim 1, wherein

when the point light source detection unit has detected a point light source, the image processing unit changes image processing to be applied between a region that corresponds to the point light source and a region that does not correspond to the point light source in the input image.

11. An image processing method comprising:

an image processing step of executing image processing on an input image;

a point light source detection step of detecting a point light source included in the input image;

a scene determination step of determining whether or not the input image shows a vivid scene based on a detection result of the point light source detection step and an image signal of the input image; and

a control step of controlling the image processing unit to change image processing for the input image in accordance with a determination result of the scene determination step.