Color imaging apparatus having color imaging element

A color imaging apparatus comprising:

• a single-plate color imaging element comprising:
• a plurality of pixels including photoelectric conversion elements arranged in a horizontal direction and a vertical direction;
• and color filters of a predetermined color filter array arranged on the plurality of pixels, wherein the color filter array includes first filters corresponding to a first color that most contributes to obtaining luminance signals and second filters corresponding to two or more second colors other than the first color, the first and second filters being periodically arranged, and two or more pixels out of a plurality of pixels corresponding to the first filters are arranged so that the two or more pixels are adjacent to each other in each of the horizontal direction, the vertical direction, an upper right oblique direction and an upper left oblique direction;
• an image acquisition unit configured to acquire a mosaic image corresponding to the color filter array from the color imaging element;
• a direction determination unit configured to acquire, for a target pixel for demosaicing processing extracted from the mosaic image, pixel values which correspond to the first filters near the target pixel and are conterminously arranged in each of the horizontal direction, the vertical direction, the upper right oblique direction and the upper left oblique direction, the direction determination unit configured to determine which one of the horizontal direction, the vertical direction, the upper right oblique direction and the upper left oblique direction is a correlation direction of luminance based on the pixel values of the conterminously arranged pixels;
• and
• a demosaicing processing unit configured to calculate a pixel value of another color at a pixel position of the target pixel for the demosaicing processing extracted from the mosaic image, the demosaicing processing unit configured to use a pixel value of a pixel of the another color in the correlation direction determined by the direction determination unit to calculate the pixel value of the another color,
• wherein the direction determination unit calculates ratios of pixel values of adjacent pixels in each of the horizontal direction, the vertical direction, the upper right oblique direction and the upper left oblique direction and determines a direction with a ratio closest to 1 among the ratios of the horizontal direction, the vertical direction, the upper right oblique direction and the upper left oblique direction as the correlation direction.

A image processing method for a single-plate color imaging element comprising:

• a plurality of pixels including photoelectric conversion elements arranged in a horizontal direction and a vertical direction;
• and color filters of a predetermined color filter array arranged on the plurality of pixels, wherein the color filter array includes first filters corresponding to a first color that most contributes to obtaining luminance signals and second filters corresponding to two or more second colors other than the first color, the first and second filters being periodically arranged, and the color filter array includes a first portion in which two or more pixels corresponding to the first filters are adjacent to each other in the horizontal direction with no pixel corresponding to colors other than the first color therebetween, a second portion in which two or more pixels corresponding to the first filters are adjacent to each other in the vertical direction with no pixel corresponding to colors other than the first color therebetween, a third portion in which two or more pixels corresponding to the first filters are adjacent to each other in an upper right oblique direction with no pixel corresponding to colors other than the first color therebetween, and a fourth portion in which two or more pixels corresponding to the first filters are adjacent to each other in an upper left oblique direction with no pixel corresponding to colors other than the first color therebetween,
• the method comprising:
• acquiring a mosaic image corresponding to the color filter array from the color imaging element;
• acquiring, for a target pixel for demosaicing processing extracted from the mosaic image, pixel values which correspond to the first filters near the target pixel and are conterminously arranged in each of the horizontal direction, the vertical direction, the upper right oblique direction and the upper left oblique direction and determining which one of the horizontal direction, the vertical direction, the upper right oblique direction and the upper left oblique direction is a correlation direction of luminance based on the pixel values of the conterminously arranged pixels, wherein difference absolute values of pixel values of adjacent pixels are calculated in each of the horizontal direction, the vertical direction, the upper right oblique direction and the upper left oblique direction, and a direction with a minimum difference absolute value among the difference absolute values is determined as the correlation direction;
• and
• calculating a pixel value of another color at a pixel position of the target pixel for the demosaicing processing extracted from the mosaic image, wherein a pixel value of a pixel of the another color in the correlation direction detennined by the direction determination unit is used to calculate the pixel value of the another color.

A image processing method for a single-plate color imaging element comprising:

• a plurality of pixels including photoelectric conversion elements arranged in a horizontal direction and a vertical direction;
• and color filters of a predetermined color filter array arranged on the plurality of pixels, wherein the color filter array includes first filters corresponding to a first color that most contributes to obtaining luminance signals and second filters corresponding to two or more second colors other than the first color, the first and second filters being periodically arranged, and two or more pixels out of a plurality of pixels corresponding to the first filters are arranged so that the two or more pixels are adjacent to each other in each of the horizontal direction, the vertical direction, an upper right oblique direction and an upper left oblique direction,
• the method comprising:
• acquiring a mosaic image corresponding to the color filter array from the color imaging element;
• acquiring, for a target pixel for demosaicing processing extracted from the mosaic image, pixel values which correspond to the first filters near the target pixel and are conteii iinously arranged in each of the horizontal direction, the vertical direction, the upper right oblique direction and the upper left oblique direction and determining which one of the horizontal direction, the vertical direction, the upper right oblique direction and the upper left oblique direction is a correlation direction of luminance based on the pixel values of the conterminously arranged pixels wherein ratios of pixel values of adjacent pixels are calculated in each of the horizontal direction, the vertical direction, the upper right oblique direction and the upper left direction and a direction with a ratio closest to 1 among the ratios of the horizontal direction, the vertical direction, the upper right oblique direction and the upper left direction is determined as the correlation direction;
• and
• calculating a pixel value of another color at a pixel position of the target pixel for the demosaicing processing extracted from the mosaic image, wherein a pixel value of a pixel of the another color in the correlation direction determined by the direction determination unit is used to calculate the pixel value of the another color.