Raw image processing system and method

A camera including an image sensor with a color filter array, wherein the image sensor includes an array of photosites, each photosite being configured to receive light at a respective one of a plurality of colors in the color filter array and output a pixel value indicating an intensity of light captured at the corresponding photosite, the pixel values representing raw image data, said color filter array comprising filters of a first color, a second color, and a third color, such that each pixel value corresponds to a color of the filter corresponding to its respective photosite, said camera further including an image processing system configured to:

• generate a luminance image comprising a plurality of luminance values at a first resolution, said luminance values being directly calculated by applying a first filter kernel to a plurality of pixel values, wherein each luminance value represents a weighted sum of pixel values corresponding to each of the first color, second color, and third color, and wherein a ratio of weightings of pixel values corresponding to the first, second, and third colors is 1:2:1;
• generate a first chrominance image comprising a plurality of chrominance values at a second resolution that is lower than the first resolution, said chrominance values being directly calculated by applying a second filter kernel to a plurality of pixel values;
• and
• generate a second chrominance image comprising a plurality of chrominance values at said second resolution, said chrominance values being directly calculated by applying a third filter kernel to a plurality of pixel values;
• wherein said luminance image, said first chrominance image, and said second chrominance image together represent said raw image data such that, in combination, said luminance image, said first chrominance image, and said second chrominance image are able to represent the same range of colors that are able to be represented in the raw image data.

An image processing system for a camera for generating image data, the camera including an image sensor with a color filter array, wherein the image sensor includes an array of photosites, each photosite being configured to receive light at a respective one of a plurality of colors in the color filter array and output a pixel value indicating an intensity of light captured at the corresponding photosite, said color filter array comprising filters of a first color, a second color, and a third color, such that each pixel value corresponds to a color of the filter corresponding to its respective photosite, the image processing system configured to perform a process comprising:

• receiving image data, the image data comprising raw image data representing an array of pixel values, each of said pixel values representing an intensity of light captured at a corresponding photosite in an array of photosites of the image sensor of said camera;
• generating a luminance image comprising a plurality of luminance values at a first resolution, wherein each luminance value represents a weighted sum of pixel values corresponding to each of the first color, second color, and third color, and wherein a ratio of weightings of pixel values corresponding to the first, second, and third colors is 1:2:1;
• generating a first chrominance image comprising a first plurality of chrominance values at a resolution that is lower than the first resolution;
• and
• generating a second chrominance image comprising a second plurality of chrominance values, different than the first plurality of chrominance values, at a resolution that is lower than the first resolution;
• wherein:
• the plurality of luminance values, the first plurality of chrominance values and the second plurality of chrominance values are directly calculated in respective filter kernel application processes;
• and
• said luminance image, said first chrominance image and said second chrominance image together represent said raw image data such that, in combination, said luminance image, said first chrominance image, and said second chrominance image are able to represent the same range of colors that are able to be represented in the raw image data.