Pixel interpolation apparatus, imaging apparatus, pixel interpolation processing method, integrated circuit, and non-transitory computer readable storage medium
First Claim
1. A pixel interpolation apparatus that performs pixel interpolation processing on an image obtained by an imaging unit, the imaging unit having color filters of four different colors arranged in a predetermined pattern, the imaging unit including at least white component pixels, the apparatus comprising:
- a color saturation evaluation value obtaining unit configured to evaluate color saturation of a predetermined image area of the image, and obtain a color saturation evaluation value for the image area;
a correlation degree obtaining unit configured to obtain degrees of correlation for a plurality of pairs in two directions orthogonal to each other in the image using pixel data for an area around a target pixel;
a pixel interpolation method determination unit configured to determine a pixel interpolation method for the target pixel based on the color saturation evaluation value obtained by the color saturation evaluation value obtaining unit and the degree of correlation obtained by the correlation degree obtaining unit;
an interpolation unit configured to perform pixel interpolation processing on the image with the pixel interpolation method determined by the pixel interpolation method determination unit, and obtain image data in a predetermined color space defining at least a white component value; and
a color space conversion unit configured to, in the image data in the color space obtained by the interpolation unit,(1) use a white component signal of a pixel obtained by the interpolation unit as a luminance signal and obtain a color difference signal by using the luminance signal, and a first color component signal and a second color component signal that are other than the white component signal of the pixel obtained by the interpolation unit when the target pixel is a white component pixel or when a white component signal of the target pixel is obtained through interpolation processing performed using a white component pixel around the target pixel, and(2) generate a luminance signal from a first color component signal, a second color component signal, and a third color component signal that are other than a white component signal of a pixel obtained by the interpolation unit, and obtain a color difference signal using the luminance signal, and the first color component signal and the second color component signal for the pixel obtained by the interpolation unit when the target pixel is not a white component pixel and a white component signal of the target pixel is not obtained through interpolation processing performed using a W-component pixel around the target pixel.
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Abstract
A pixel interpolation apparatus, an imaging apparatus, a program, and an integrated circuit allow appropriate pixel interpolation processing on an image signal obtained by a single-chip image sensor having a WRGB color filter array. An imaging apparatus includes an imaging unit, a signal processing unit, and a pixel interpolation processing unit. The apparatus calculates a degree of correlation for pairs in two orthogonal directions for an image signal (Raw image) obtained by the imaging unit including a single-chip image sensor having a WRGB color filter array using pixel data in an area around a target pixel, using the correlation degree as a determination criterion in the interpolation processing. The imaging apparatus selectively uses a luminance signal generated from R, G, and B-component signals or a luminance signal generated from a W-component signal to perform pixel interpolation processing with higher accuracy and obtain a YCbCr signal with higher accuracy.
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Citations
10 Claims
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1. A pixel interpolation apparatus that performs pixel interpolation processing on an image obtained by an imaging unit, the imaging unit having color filters of four different colors arranged in a predetermined pattern, the imaging unit including at least white component pixels, the apparatus comprising:
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a color saturation evaluation value obtaining unit configured to evaluate color saturation of a predetermined image area of the image, and obtain a color saturation evaluation value for the image area; a correlation degree obtaining unit configured to obtain degrees of correlation for a plurality of pairs in two directions orthogonal to each other in the image using pixel data for an area around a target pixel; a pixel interpolation method determination unit configured to determine a pixel interpolation method for the target pixel based on the color saturation evaluation value obtained by the color saturation evaluation value obtaining unit and the degree of correlation obtained by the correlation degree obtaining unit; an interpolation unit configured to perform pixel interpolation processing on the image with the pixel interpolation method determined by the pixel interpolation method determination unit, and obtain image data in a predetermined color space defining at least a white component value; and a color space conversion unit configured to, in the image data in the color space obtained by the interpolation unit, (1) use a white component signal of a pixel obtained by the interpolation unit as a luminance signal and obtain a color difference signal by using the luminance signal, and a first color component signal and a second color component signal that are other than the white component signal of the pixel obtained by the interpolation unit when the target pixel is a white component pixel or when a white component signal of the target pixel is obtained through interpolation processing performed using a white component pixel around the target pixel, and (2) generate a luminance signal from a first color component signal, a second color component signal, and a third color component signal that are other than a white component signal of a pixel obtained by the interpolation unit, and obtain a color difference signal using the luminance signal, and the first color component signal and the second color component signal for the pixel obtained by the interpolation unit when the target pixel is not a white component pixel and a white component signal of the target pixel is not obtained through interpolation processing performed using a W-component pixel around the target pixel. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A pixel interpolation processing method for performing pixel interpolation on an image obtained by an imaging unit, the imaging unit having color filters of four different colors arranged in a predetermined pattern and including at least white component pixels,
the method comprising: -
evaluating color saturation of a predetermined image area of the image, and obtaining a color saturation evaluation value for the image area; obtaining degrees of correlation for a plurality of pairs in two directions orthogonal to each other in the image using pixel data for an area around a target pixel; determining a pixel interpolation method for the target pixel based on the color saturation evaluation value obtained by the step of obtaining the color saturation evaluation value and the degree of correlation obtained by the step of obtaining the degree of correlation; performing pixel interpolation processing on the image with the pixel interpolation method determined by the step of determining the pixel interpolation method, and obtaining image data in a predetermined color space defining at least a white component value; and in the color space obtained by the step of performing the pixel interpolation processing, (1) using a white component signal of a pixel obtained by the step of performing the pixel interpolation processing as a luminance signal and obtaining a color difference signal by using the luminance signal, and a first color component signal and a second color component signal that are other than the white component signal of the pixel obtained by the step of performing the pixel interpolation processing when the target pixel is a white component pixel or when a white component signal of the target pixel is obtained through interpolation processing performed using a white component pixel around the target pixel in the image data, and (2) generating a luminance signal from a first color component signal, a second color component signal, and a third color component signal that are other than a white component signal of a pixel obtained by the step of performing the pixel interpolation processing, and obtaining a color difference signal using the luminance signal, and the first color component signal and the second color component signal for the pixel obtained by the step of performing the pixel interpolation processing when the target pixel is not a white component pixel and a white component signal of the target pixel is not obtained through interpolation processing performed using a W-component pixel around the target pixel. - View Dependent Claims (10)
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9. An integrated circuit that performs pixel interpolation processing on an image obtained by an imaging unit, the imaging unit having color filters of four different colors arranged in a predetermined pattern and including at least white component pixels, the integrated circuit comprising:
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a color saturation evaluation value obtaining unit configured to evaluate color saturation of a predetermined image area of the image, and obtain a color saturation evaluation value for the image area; a correlation degree obtaining unit configured to obtain degrees of correlation for a plurality of pairs in two directions orthogonal to each other in the image using pixel data for an area around a target pixel; a pixel interpolation method determination unit configured to determine a pixel interpolation method for the target pixel based on the color saturation evaluation value obtained by the color saturation evaluation value obtaining unit and the degree of correlation obtained by the correlation degree obtaining unit; an interpolation unit configured to perform pixel interpolation processing on the image with the pixel interpolation method determined by the pixel interpolation method determination unit, and obtain image data in a predetermined color space defining at least a white component value; and a color space conversion unit configured to, in the image data in the color space obtained by the interpolation unit, (1) use a white component signal of a pixel obtained by the interpolation unit as a luminance signal and obtain a color difference signal by using the luminance signal, and a first color component signal and a second color component signal that are other than the white component signal of the pixel obtained by the interpolation unit when the target pixel is a white component pixel or when a white component signal of the target pixel is obtained through interpolation processing performed using a white component pixel around the target pixel, and (2) generate a luminance signal from a first color component signal, a second color component signal, and a third color component signal that are other than a white component signal of a pixel obtained by the interpolation unit, and obtain a color difference signal using the luminance signal, and the first color component signal and the second color component signal for the pixel obtained by the interpolation unit when the target pixel is not a white component pixel and a white component signal of the target pixel is not obtained through interpolation processing performed using a W-component pixel around the target pixel in the image data in the color space obtained by the interpolation unit.
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Specification