Detecting edges in a digital images

An image processing method that receives mosaic image data having settings of only one color component, among three color components R, G, and B corresponding to three primary colors of light, in each pixel and makes the received mosaic image data subject to a series of image processing to generate an edge map that identifies pixels of the mosaic image data through which an edge passes,

• the image processing method comprising:
• receiving, as the mosaic image data, image data expressed by a combination of pixel columns with alternate arrangement of pixels of the G component and pixels of the R component as another color component in a vertical direction, pixel columns with alternate arrangement of pixels of the G component and pixels of the B component as another color component in the vertical direction, pixel rows with alternate arrangement of pixels of the G component and pixels of the R component as another color component in a horizontal direction, and pixel rows with alternate arrangement of pixels of the G component and pixels of the B component as another color component in the horizontal direction;
• obtaining the G component and another color component in each pixel included in each of the pixel columns of the mosaic image data, and computing a vertical-direction color difference component between the G component and another color component in each pixel included in each of the pixel columns in the vertical direction;
• obtaining the G component and another color component in each pixel included in each of the pixel rows of the mosaic image data, and computing a horizontal-direction color difference component between the G component and another color component in each pixel included in each of the pixel rows in the horizontal direction;
• selecting pixels from the mosaic image data, and in each such pixel location comparing the sign of the vertical color difference component of the target pixel to the signs of the vertical color difference components of the pixels above and below the target pixel, comparing the sign of the horizontal color difference component of the target pixel to the signs of the horizontal color difference components of the pixels to the left and to the right of the target pixel, setting the corresponding edge map value of the edge map to 1 where the signs in one or more of the comparisons are not equal, and setting the corresponding edge map value of the edge map to 0 where the signs in all of the comparisons are equal.

A non-transitory computer-readable medium having a program that causes a computer to actualize a method of receiving mosaic image data having settings of only one color component, among three color components R, G, and B corresponding to three primary colors of light, in each pixel and making the received mosaic image data subject to a series of image processing to generate an edge map that identifies pixels of the mosaic image data through which an edge passes,

• the program causing the computer to attain the functions of:
• receiving, as the mosaic image data, image data expressed by a combination of pixel columns with alternate arrangement of pixels of the G component and pixels of the R component as another color component in a vertical direction, pixel columns with alternate arrangement of pixels of the G component and pixels of the B component as another color component in the vertical direction, pixel rows with alternate arrangement of pixels of the G component and pixels of the R component as another color component in a horizontal direction, and pixel rows with alternate arrangement of pixels of the G component and pixels of the B component as another color component in the horizontal direction;
• obtaining the G component and another color component in each pixel included in each of the pixel columns of the mosaic image data, and computing a vertical-direction color difference component between the G component and another color component in each pixel included in each of the pixel columns in the vertical direction;
• obtaining the G component and another color component in each pixel included in each of the pixel rows of the mosaic image data, and computing a horizontal-direction color difference component between the G component and another color component in each pixel included in each of the pixel rows in the horizontal direction;
• selecting pixels from the mosaic image data, and in each such pixel location comparing the sign of the vertical color difference component of the target pixel to the signs of the vertical color difference components of the pixels above and below the target pixel, comparing the sign of the horizontal color difference component of the target pixel to the signs of the horizontal color difference components of the pixels to the left and to the right of the target pixel, setting the corresponding edge map value of the edge map to 1 where the signs in one or more of the comparisons are not equal, and setting the corresponding edge map value of the edge map to 0 where the signs in all of the comparisons are equal.