Image processing apparatus, image processing method, program and electronic apparatus

Patent metadata

Field	Value
Publication number	US-9432646-B2
Application number	US-201514597753-A
Country	US
Kind code	B2
Filing date	Jan 15, 2015
Priority date	Jan 22, 2014
Publication date	Aug 30, 2016
Grant date	Aug 30, 2016

Abstract

According to an embodiment of the present disclosure, there is provided an image processing apparatus including a comparing unit to perform comparison using at least one of a maximum value and an average value of luminance signals of an input image, with a saturation level as a reference of comparison, the saturation level being a level of light accumulation performed for a predetermined time length which is one of a plurality of time lengths for accumulating light in imaging of the input image; a tone curve generator to generate a tone curve to be used for performing compression processing to luminance gradation of the input image, on the basis of a result of the comparison being made; and a luminance gradation compression processor to perform compression processing to luminance gradation of the input image, according to the tone curve being generated.

First claim

What is claimed is:

1. An image processing apparatus, comprising:
a comparing unit configured to perform a comparison using at least one of a maximum value and an average value of luminance signals of an input image, with a saturation level as a reference of comparison, the saturation level being a level of light accumulation performed for a predetermined time length, the predetermined time length being one out of a plurality of time lengths for accumulating light in imaging of the input image;
a tone curve generator configured to generate a tone curve to be used for performing compression processing to a luminance gradation of the input image, on the basis of a result of the comparison made by the comparing unit; and
a luminance gradation compression processor configured to perform compression processing to the luminance gradation of the input image, according to the tone curve being generated by the tone curve generator.

2. The image processing apparatus according to claim 1 , wherein
the comparing unit is configured to compare the maximum value of the luminance signals of the input image with a first reference value, the first reference value being based on the saturation level of the light accumulation for the predetermined time length as a reference, and
the tone curve generator is configured to,
if the maximum value of the luminance signals of the input image is equal to or lower than the first reference value, replace the maximum value of the luminance signals of the input image with the first reference value, to generate the tone curve.

3. The image processing apparatus according to claim 1 , wherein
the comparing unit is configured to compare the average value of the luminance signals of the input image with a second reference value, the second reference value being based on the saturation level of the light accumulation for the predetermined time length as a reference, and
the tone curve generator is configured to,
if the average value of the luminance signals of the input image is equal to or lower than the second reference value, generate the tone curve in a linear fashion.

4. The image processing apparatus according to claim 1 , wherein
the comparing unit is configured to compare a difference value between the maximum value and the average value of the luminance signals of the input image with a third reference value, the third reference value being based on the saturation level of the light accumulation for the predetermined time length as a reference, and
the tone curve generator is configured to,
if the difference value between the maximum value and the average value of the luminance signals of the input image is equal to or lower than the third reference value, generate the tone curve in a linear fashion.

5. The image processing apparatus according to claim 1 , wherein
the comparing unit is configured to,
when light is accumulated by a long-time accumulation and a short-time accumulation in the imaging of the input image, perform the comparison using the saturation level of the long-time accumulation as the reference of comparison.

6. The image processing apparatus according to claim 1 , wherein
the comparing unit is configured to,
when light is accumulated by a long-time accumulation and a short-time accumulation in the imaging of the input image, perform the comparison using the saturation level of the short-time accumulation as the reference of comparison.

7. The image processing apparatus according to claim 1 , wherein
the comparing unit is configured to compare the average value of the luminance signals of the input image with a fourth reference value, the fourth reference value being based on the saturation level of the accumulation for the predetermined time length as a reference, and
the tone curve generator is configured to,
if the average value of the luminance signals of the input image is equal to or lower than the fourth reference value, generate the tone curve which suppresses an output equal to or lower than the average value of the luminance signals of the input image.

8. An image processing method comprising:
performing a comparison using at least one of a maximum value and an average value of luminance signals of an input image, with a saturation level as a reference of comparison, the saturation level being a level of light accumulation performed for a predetermined time length, the predetermined time length being one out of a plurality of time lengths for accumulating light in imaging of the input image;
generating a tone curve to be used for performing compression processing to a luminance gradation of the input image, on the basis of a result of the comparison being made; and
performing compression processing to the luminance gradation of the input image, according to the tone curve being generated.

9. An electronic apparatus, comprising
an image processing apparatus, having
a comparing unit configured to perform a comparison using at least one of a maximum value and an average value of luminance signals of an input image, with a saturation level as a reference of comparison, the saturation level being a level of light accumulation performed for a predetermined time length, the predetermined time length being one out of a plurality of time lengths for accumulating light in imaging of the input image,

a tone curve generator configured to generate a tone curve to be used for performing compression processing to a luminance gradation of the input image, on the basis of a result of the comparison made by the comparing unit, and
a luminance gradation compression processor configured to perform compression processing to the luminance gradation of the input image, according to the tone curve being generated by the tone curve generator.

10. The electronic apparatus according to claim 9 , wherein
the comparing unit is configured to compare the maximum value of the luminance signals of the input image with a first reference value, the first reference value being based on the saturation level of the light accumulation for the predetermined time length as a reference, and
the tone curve generator is configured to,
if the maximum value of the luminance signals of the input image is equal to or lower than the first reference value, replace the maximum value of the luminance signals of the input image with the first reference value, to generate the tone curve.

11. The electronic apparatus according to claim 9 , wherein
the comparing unit is configured to compare the average value of the luminance signals of the input image with a second reference value, the second reference value being based on the saturation level of the light accumulation for the predetermined time length as a reference, and
the tone curve generator is configured to,
if the average value of the luminance signals of the input image is equal to or lower than the second reference value, generate the tone curve in a linear fashion.

12. The electronic apparatus according to claim 9 , wherein
the comparing unit is configured to compare a difference value between the maximum value and the average value of the luminance signals of the input image with a third reference value, the third reference value being based on the saturation level of the light accumulation for the predetermined time length as a reference, and
the tone curve generator is configured to,
if the difference value between the maximum value and the average value of the luminance signals of the input image is equal to or lower than the third reference value, generate the tone curve in a linear fashion.

13. The electronic apparatus according to claim 9

Assignees

• Sony Corp

Inventors

• Kawaguchi Shunji

Classifications

• H04N23/83 Primary

  specially adapted for colour signals · CPC title

• H04N2209/042

  having a single pick-up sensor · CPC title

• H04N9/69 Primary

  for modifying the colour signals by gamma correction (controlling camera response for colour signals H04N23/83) · CPC title