Interpolation processing apparatus and recording medium having interpolation processing program recorded therein

Abstract

A first interpolation processing apparatus that engages in processing on image data which are provided in a calorimetric system constituted of first˜nth (n≧2) color components and include color information corresponding to a single color component provided at each pixel to determine an interpolation value equivalent to color information corresponding to the first color component for a pixel at which the first color component is missing, includes: an interpolation value calculation section that uses color information at pixels located in a local area containing an interpolation target pixel to undergo interpolation processing to calculate an interpolation value including, at least (1) local average information of the first color component with regard to the interpolation target pixel and (2) local curvature information corresponding to at least two color components with regard to the interpolation target pixel.

What is claimed is:  
     
         1 . An interpolation processing apparatus that engages in processing on image data which are provided in a colorimetric system constituted of first˜nth (n≧2) color components and include color information corresponding to a single color component provided at each pixel to determine an interpolation value equivalent to color information corresponding to the first color component for a pixel at which the first color component is missing, comprising: 
 an interpolation value calculation section that uses color information at pixels located in a local area containing an interpolation target pixel to undergo interpolation processing to calculate an interpolation value including, at least 
 (1) local average information of the first color component with regard to the interpolation target pixel and  
 (2) local curvature information corresponding to at least two color components with regard to the interpolation target pixel.  
 
 
     
     
         2 . An interpolation processing apparatus according to  claim 1 , wherein: 
 said interpolation value calculation section calculates, as said local curvature information corresponding to at least two color components, 
 (1) local curvature information based upon a color component matching a color component at the interpolation target pixel and  
 (2) local curvature information based upon a color component other than the color component at the interpolation target pixel.  
   
     
     
         3 . An interpolation processing apparatus that engages in processing on image data which are provided in a colorimetric system constituted of first˜nth (n≧2) color components and include color information corresponding to a single color component provided at each pixel to determine an interpolation value equivalent to color information corresponding to the first color component for a pixel at which the first color component is missing, comprising: 
 an interpolation value calculation section that uses color information at pixels located in a local area containing an interpolation target pixel to undergo interpolation processing to calculate an interpolation value including, at least 
 (1) local average information of the first color component with regard to the interpolation target pixel and  
 (2) local curvature information based upon a color component other than a color component at the interpolation target pixel.  
 
 
     
     
         4 . An interpolation processing apparatus that engages in processing on image data which are provided in a calorimetric system constituted of first˜nth (n≧2) color components and include color information corresponding to a single color component provided at each pixel to determine an interpolation value equivalent to color information corresponding to the first color component for a pixel at which the first color component is missing, comprising: 
 an interpolation value calculation section that uses color information at pixels located in a local area containing an interpolation target pixel to undergo interpolation processing to calculate an interpolation value including, at least 
 (1) local average information of the first color component with regard to the interpolation target pixel and  
 (2) local curvature information corresponding to the first color component with respect to the interpolation target pixel.  
 
 
     
     
         5 . An interpolation processing apparatus according to  claim 1 , further comprising: 
 a first similarity judgment section that judges degrees of similarity to the interpolation target pixel along at least two directions in which pixels with color information corresponding to the first color component are connected with the interpolation target pixel; and    a second similarity judgment section that judges degrees of similarity to the interpolation target pixel along at least two directions other than the directions in which the degrees of similarity are judged by said first similarity judgment section, wherein: 
 said interpolation value calculation section selects a direction along which pixels having color information to be used to calculate said local average information of the first color component are set based upon results of a judgment made by said first similarity judgment section; 
 (1) said interpolation value calculation section selects a direction along which pixels having color information to be used to calculate said local curvature information are set based upon results of the judgment made by said first similarity judgment section if said local curvature information is “local curvature information constituted of a single color component and manifesting directionality along a direction in which degrees of similarity are judged by said first similarity judgment section”; and  
 (2) said interpolation value calculation section selects a direction along which pixels having color information to be used to calculate said local curvature information are set based upon results of a judgment made by said second similarity judgment section if said local curvature information is “local curvature information constituted of a single color component and manifesting directionality along a direction in which degrees of similarity are judged by said second similarity judgment section.” 
 
   
     
     
         6 . An interpolation processing apparatus that engages in processing on image data which are provided in a calorimetric system constituted of first˜nth (n≧2) color components and include color information corresponding to a single color component provided at each pixel to determine an interpolation value equivalent to color information corresponding to the first color component for a pixel at which the first color component is missing, comprising: 
 an interpolation value calculation section that calculates an interpolation value including at least two terms, i.e., a first term and a second term by using color information at pixels set in a local area containing an interpolation target pixel to undergo interpolation processing;  
 a first similarity judgement section that judges degrees of similarity to the interpolation target pixel along at least two directions in which pixels having color information corresponding to the first color component are connected to the interpolation target pixel; and  
 a second similarity judgment section that judges degrees of similarity to the interpolation target pixel along at least two directions other than the directions in which the degrees of similarity are judged by said first similarity judgment section, wherein: 
 said interpolation value calculation section selects a direction along which pixels having color information to be used to calculate said first term are set based upon results of a judgment made by said first similarity judgment section and selects a direction along which pixels having color information to be used to calculate said second term are set based upon results of a judgment made by said second similarity judgment section.  
 
 
     
     
         7 . An interpolation processing apparatus according to  claim 6 , wherein 
 said interpolation value calculation section:    calculates a term containing 
 (a) local average information of the first color component with regard to the interpolation target pixel and  
 (b) local curvature information constituted of a single color component and manifesting directionality along a direction in which degrees of similarity are judged by said first similarity judgment section, as said first term; and  
   calculates a term containing local curvature information constituted of a single color component and manifesting directionality along a direction in which degrees of similarity are judged by said second similarity judgment section, as said second term.    
     
     
         8 . An interpolation processing apparatus according to  claim 5 , wherein: 
 when image data are provided in a calorimetric system constituted of first˜third color components with the first color component achieving a higher spatial frequency than the second color component and the third color component, the first color component set in a checker-board pattern, the second color component and the third color component each set in a line sequence between pixels at which color information corresponding to the first color component is present and information corresponding to the second color component present at the interpolation target pixel;    said first similarity judgment section calculates similarity degrees manifested by the interpolation target pixel along two directions, i.e., a vertical direction and a horizontal direction, in which pixels with color information corresponding to the first color component that are closest to the interpolation target pixel are connected to the interpolation target pixel and makes a judgment with regard to degrees of similarity manifested by the interpolation target pixel along the vertical direction and the horizontal direction based upon a difference between said similarity degrees;    said second similarity judgment section calculates similarity degrees manifested by the interpolation target pixel along two diagonal directions in which pixels with color information corresponding to the third color component that are closest to the interpolation target pixel are connected to the interpolation target pixel and makes a judgment with regard to degrees of similarity manifested by the interpolation target pixel along the two diagonal directions based upon a difference between said similarity degrees; and    said interpolation value calculation section selects at least either the second color component or the first color component based upon which said “local curvature information constituted of a single color component and manifesting directionality along a direction in which degrees of similarity are judged by said first similarity judgment section” is provided and selects at least either the second color component or the third color component based upon which said “local curvature information constituted of a single color component and manifesting directionality along a direction in which degrees of similarity are judged by said second similarity judgment section” is provided.    
     
     
         9 . An interpolation processing apparatus according to  claim 8 , wherein: 
 when said local curvature information is “local curvature information based upon a color component other than the color component at the interpolation target pixel”, said interpolation value calculation section selects the first color component or the third color component to which said local curvature information is to correspond in conformance to the degrees of similarity judged by said second similarity judgment section.    
     
     
         10 . An interpolation processing apparatus according to  claim 9 , wherein: 
 said interpolation value calculation section calculates local curvature information based upon the first color component if said second similarity judgment section judges that roughly equal degrees of similarity manifest along the two diagonal directions and calculates local curvature information based upon the third color component if said second similarity judgment section judges that a higher degree of similarity manifests along one of the two diagonal directions compared to the other diagonal direction.    
     
     
         11 . An interpolation processing apparatus according to  claim 8 , wherein: 
 said first similarity judgment section judges that roughly equal degrees of similarity manifest along the vertical direction and the horizontal direction if a difference between the similarity degrees along the vertical direction and the horizontal direction is smaller than a specific threshold value; and    said second similarity judgment section judges that roughly equal degrees of similarity manifest along the two diagonal directions if a difference between the similarity degrees along the two diagonal directions is smaller than a specific threshold value.    
     
     
         12 . An interpolation processing apparatus according to  claim 8 , wherein: 
 said first similarity judgment section calculates the similarity degrees along the vertical direction and the horizontal direction by using color information corresponding to a plurality of color components for a single interpolation target pixel; and    said second similarity judgment section calculates the similarity degrees along the two diagonal directions by using color information corresponding to a plurality of color components for a single interpolation target pixel.    
     
     
         13 . An interpolation processing apparatus according to  claim 12 , wherein: 
 said second similarity judgment section calculates a similarity degree manifesting along each of the two diagonal directions through weighted addition of: 
 (1) a similarity degree component constituted of color information corresponding to the first color component alone;  
 (2) a similarity degree component constituted of color information corresponding to the second color component alone;  
 (3) a similarity degree component constituted of color information corresponding to the third color component alone; and  
 (4) a similarity degree component constituted of color information corresponding to the second color component and the third color component.  
   
     
     
         14 . An interpolation processing apparatus according to  claim 8 , wherein: 
 said first similarity judgment section calculates similarity degrees along the vertical direction and the horizontal direction for each pixel and makes a judgment on similarity manifested by the interpolation target pixel along the vertical direction and the horizontal direction based upon differences in similarity degrees manifesting at nearby pixels as well as at the interpolation target pixel; and    said second similarity judgment section calculates similarity degrees along the two diagonal directions for each pixel and makes a judgment on similarity manifested by the interpolation target pixel along the two diagonal directions based upon differences in similarity degrees manifesting at nearby pixels as well as at the interpolation target pixel.    
     
     
         15 . An interpolation processing apparatus that engages in processing on image data which are provided in a calorimetric system constituted of first˜nth (n≧2) color components and include color information corresponding to a single color component provided at each pixel to determine an interpolation value equivalent to color information corresponding to the first color component for a pixel at which the first color component is missing, comprising: 
 a first term calculation section that calculates a first term representing average information of the first color component with regard to an interpolation target pixel to undergo interpolation processing by using color information corresponding to color components at pixels set in a local area containing the interpolation target pixel;  
 a second term calculation section that calculates a second term representing local curvature information based upon a color component matching the color component at the interpolation target pixel with regard to the interpolation target pixel by using color information corresponding to color components at pixels set in a local area containing the interpolation target pixel; and  
 an interpolation value calculation section that calculates an interpolation value by adding said second term multiplied by a weighting coefficient constituted of color information corresponding to a plurality of color components at pixels in the local area containing the interpolation target pixel to said first term.  
 
     
     
         16 . An interpolation processing apparatus according to  claim 15 , wherein: 
 said interpolation value calculation section uses color information corresponding to a plurality of color components provided at the interpolation target pixel and at a plurality of pixels set along a predetermined direction relative to the interpolation target pixel to ascertain inclinations manifesting in color information corresponding to the individual color components along the direction and calculates said weighting coefficient in conformance to a correlation manifesting among the inclinations in the color information corresponding to the individual color components.    
     
     
         17 . An interpolation processing apparatus that implements processing for supplementing a color component value at a pixel at which information corresponding to a color component is missing in image data provided in a calorimetric system constituted of a luminance component and the color component, with the luminance component having a higher spatial frequency than the color component and the luminance component present both at pixels having information corresponding to the color component and at pixels lacking information corresponding to the color component, comprising: 
 a hue value calculation section that calculates hue values at a plurality of pixels located near an interpolation target pixel to undergo interpolation processing and having both the luminance component and the color component by using luminance component values and color component values at the individual pixels;    a hue value interpolation section that calculates a hue value at the interpolation target pixel by using a median of the hue values at the plurality of pixels calculated by said hue value calculation section; and    a color conversion section that interpolates a color component at the interpolation target pixel by using the luminance component at the interpolation target pixel to convert the hue value at the interpolation target pixel calculated by said hue value interpolation section to a color component.    
     
     
         18 . An interpolation processing apparatus that implements processing for supplementing a luminance component at a pixel at which information corresponding to a luminance component is missing and supplementing a color component at a pixel at which information corresponding to a color component is missing, on image data provided in a calorimetric system constituted of the luminance component and the color component, with the luminance component having a higher spatial frequency than the color component and a given pixel having only information corresponding to either the luminance component or the color component, comprising: 
 a luminance component interpolation section that interpolates a luminance component at a luminance component interpolation target pixel to undergo luminance component interpolation processing by using at least either “similarity manifesting between the luminance component interpolation target pixel and a pixel near the luminance component interpolation target pixel” or “a plurality of color components within a local area containing the luminance component interpolation target pixel”;    a hue value calculation section that calculates hue values at a plurality of pixels located near an interpolation target pixel to undergo color component interpolation processing, having color component values and having luminance component values interpolated by said luminance component interpolation section, by using the luminance component values and color component values at the individual pixels;    a hue value interpolation section that calculates a hue value for the interpolation target pixel by using a median of the hue values at the plurality of pixels calculated by said hue value calculation section; and    a color conversion section that interpolates a color component value for the interpolation target pixel by using the luminance component value at the interpolation target pixel to convert the hue value at the interpolation target pixel calculated by said hue value interpolation section to a color component value.    
     
     
         19 . An interpolation processing apparatus according to  claim 17 , wherein: 
 when the luminance component in the image data corresponds to a green color component and the color component in the image data corresponds to a red color component and a blue color component,    said hue value interpolation section calculates a hue value for the interpolation target pixel by using a median of hue values containing the red color component at pixels near the interpolation target pixel if the green color component is present but the red color component is missing at the interpolation target pixel and calculates a hue value for the interpolation target pixel by using a median of hue values containing the blue color component at pixels near the interpolation target pixel if the green color component is present but the blue color component is missing at the interpolation target pixel.    
     
     
         20 . An interpolation processing apparatus according to  claim 17 , wherein: 
 when the luminance component in the image data corresponds to a green color component and the color component in the image data corresponds to a red color component and a blue color component,    said hue value interpolation section calculates a hue value for the interpolation target pixel by using a median of hue values containing the red color component at pixels set near the interpolation target pixel if the blue color component is present but the red color component is missing at the interpolation target pixel.    
     
     
         21 . An interpolation processing apparatus according to  claim 17 , wherein: 
 when the luminance component in the image data corresponds to a green color component and the color component in the image data corresponds to a red color component and a blue color component,    said hue value interpolation section calculates a hue value for the interpolation target pixel by using a median of hue values containing the blue color component at pixels set near the interpolation target pixel if the red color component is present but the blue color component is missing at the interpolation target pixel.    
     
     
         22 . An interpolation processing apparatus according to  claim 17 , with a color component missing at the interpolation target pixel present at only one pixel among four pixels set symmetrically along the vertical direction and the horizontal direction, wherein said hue value interpolation section comprises: 
 a first hue value interpolation unit that calculates a hue value for the interpolation target pixel by using a median of hue values at a plurality of diagonally adjacent pixels if the hue values of the plurality of diagonally adjacent pixels adjacent to the interpolation target pixel along diagonal directions have been calculated by said hue value calculation section; and    a second hue value interpolation unit that calculates a hue value for the interpolation target pixel by using a median of hue values at a plurality of vertically and horizontally adjacent pixels if the hue values of the plurality of vertically and horizontally adjacent pixels adjacent to the interpolation target pixel in the vertical direction and the horizontal direction have been calculated by said hue value calculation section or said first hue value interpolation unit.    
     
     
         23 . A recording medium having recorded therein an interpolation processing program to implement on a computer processing for determining an interpolation value equivalent to color information corresponding to a first color component missing at a pixel, on image data provided in a colorimetric system constituted of first˜nth (n≧2) color components with color information corresponding to a single color component present at each pixel, said interpolation processing program comprising: 
 an interpolation value calculation step in which an interpolation value including, at least 
 (1) local average information of the first color component with regard to an interpolation target pixel to undergo interpolation processing and  
 (2) local curvature information corresponding to at least two color components with regard to the interpolation target pixel, is calculated by using color information provided at pixels set within a local area containing the interpolation target pixel.  
 
 
     
     
         24 . A recording medium having recorded therein an interpolation processing program to implement on a computer processing for determining an interpolation value equivalent to color information corresponding to a first color component missing at a pixel, on image data provided in a colorimetric system constituted of first˜nth (n≧2) color components with color information corresponding to a single color component present at each pixel, said interpolation processing program comprising: 
 an interpolation value calculation step in which an interpolation value including, at least 
 (1) local average information of the first color component with regard to an interpolation target pixel to undergo the interpolation processing; and  
 (2) local curvature information based upon a color component other than a color component at the interpolation target pixel, is calculated by using color information provided at pixels set within a local area containing the interpolation target pixel.  
 
 
     
     
         25 . A recording medium having recorded therein an interpolation processing program to implement on a computer processing for determining an interpolation value equivalent to color information corresponding to a first color component missing at a pixel, on image data provided in a calorimetric system constituted of first˜nth (n≧2) color components with color information corresponding to a single color component present at each pixel, said interpolation processing program comprising: 
 an interpolation value calculation step in which an interpolation value including, at least 
 (1) local average information of the first color component with regard to an interpolation target pixel to undergo the interpolation processing, and  
 (2) local curvature information corresponding to the first color component with respect to the interpolation target pixel, is calculated by using color information provided at pixels set within a local area containing the interpolation target pixel.  
 
 
     
     
         26 . A recording medium having recorded therein an interpolation processing program to implement on a computer processing for determining an interpolation value equivalent to color information corresponding to a first color component missing at a pixel, on image data provided in a colorimetric system constituted of first˜nth (n≧2) color components with color information corresponding to a single color component present at each pixel, said interpolation processing program comprising: 
 an interpolation value calculation step in which an interpolation value including at least two terms, i.e., a first term and a second term is calculated by using color information at pixels set within a local area containing an interpolation target pixel to undergo interpolation processing;  
 a first similarity judgment step in which degrees of similarity to the interpolation target pixel are judged along at least two directions in which pixels having color information corresponding to the first color component are connected with the interpolation target pixel; and  
 a second similarity judgment step in which degrees of similarity to the interpolation target pixel are judged along at least two directions other than the directions along which the degrees of similarity are judged in said first similarity judgment step, wherein:  
 in said interpolation value calculation step, a direction in which pixels having color information to be used to calculate said first term are set is selected based upon results of a judgment made in said first similarity judgment step and a direction in which pixels having color information to be used to calculate said second term are set is selected based upon results of a judgment made in said second similarity judgment step.  
 
     
     
         27 . A recording medium having recorded therein an interpolation processing program to implement on a computer processing for determining an interpolation value equivalent to color information corresponding to a first color component missing at a pixel, on image data provided in a calorimetric system constituted of first˜nth (n≧2) color components with color information corresponding to a single color component present at each pixel, said interpolation processing program comprising: 
 a first term calculation step in which a first term representing average information of the first color component with regard to an interpolation target pixel to undergo interpolation processing is calculated by using color information corresponding to a color component at pixels set within a local area containing the interpolation target pixel;  
 a second term calculation step in which a second term representing local curvature information based upon a color component matching the color component at the interpolation target pixel is calculated with regard to the interpolation target pixel by using color information corresponding to a color component at pixels set within a local area containing the interpolation target pixel; and  
 an interpolation value calculation step in which an interpolation value is calculated by adding said second term multiplied by a weighting coefficient constituted of color information corresponding to a plurality of color components provided at pixels set within a local area containing the interpolation target pixel to the first term.  
 
     
     
         28 . A recording medium having recorded therein an interpolation processing program for implementing on a computer processing supplementing a color component value at a pixel at which information corresponding to a color component is missing, on image data provided in a colorimetric system constituted of a luminance component and the color component, with the luminance component having a higher spatial frequency than the color component and the luminance component present both at pixels having information corresponding to the color component and at pixels lacking information corresponding to the color component; said interpolation processing program comprising: 
 a hue value calculation step in which hue values for a plurality of pixels near an interpolation target pixel to undergo interpolation processing and having information corresponding to both the luminance component and the color component are calculated by using luminance component values and color component values at the individual pixels;    a hue value interpolation step in which a hue value for the interpolation target pixel is calculated by using a median of the hue values at the plurality of pixels calculated in the hue value calculation step; and    a color conversion step in which a color component value at the interpolation target pixel is interpolated by using a value indicated by the luminance component present at the interpolation target pixel to convert the hue value of the interpolation target pixel calculated in the hue value interpolation step to a color component value.    
     
     
         29 . A recording medium having recorded therein an interpolation processing program for implementing on a computer processing for supplementing a luminance component value at a pixel at which information corresponding to a luminance component is missing and a color component value at a pixel at which information corresponding to a color component missing, on image data provided in a calorimetric system constituted of the luminance component and the color component, with the luminance component having a higher spatial frequency than the color component and information corresponding to either the luminance component or the color component present at each pixel, said interpolation processing program comprising: 
 a luminance component interpolation step in which a luminance component value is interpolated for a luminance component interpolation target pixel to undergo luminance component interpolation processing by using at least either “similarity between the luminance component interpolation target pixel and a pixel near the luminance component interpolation target pixel” or “information corresponding to a plurality of color components within a local area containing the luminance component interpolation target pixel”;    a hue value calculation step in which hue values at a plurality of pixels located near an interpolation target pixel to undergo color component interpolation processing, having color component values and having luminance component values interpolated in said luminance component interpolation step are calculated by using the luminance component values and color component values at the individual pixels;    a hue value interpolation step in which a hue value for the interpolation target pixel is calculated by using a median of the hue values at the plurality of pixels calculated in the hue value calculation step; and    a color conversion step in which a color component value is interpolated for the interpolation target pixel by using the luminance component value at the interpolation target pixel to convert the hue value at the interpolation target pixel calculated in said hue value interpolation step to a color component value.    
     
     
         30 . An interpolation processing apparatus according to  claim 2 , further comprising: 
 a first similarity judgment section that judges degrees of similarity to the interpolation target pixel along at least two directions in which pixels with color information corresponding to the first color component are connected with the interpolation target pixel; and    a second similarity judgment section that judges degrees of similarity to the interpolation target pixel along at least two directions other than the directions in which the degrees of similarity are judged by said first similarity judgment section, wherein:    said interpolation value calculation section selects a direction along which pixels having color information to be used to calculate said local average information of the first color component are set based upon results of a judgment made by said first similarity judgment section; 
 (1) said interpolation value calculation section selects a direction along which pixels having color information to be used to calculate said local curvature information are set based upon results of the judgment made by said first similarity judgment section if said local curvature information is “local curvature information constituted of a single color component and manifesting directionality along a direction in which degrees of similarity are judged by said first similarity judgment section”; and  
 (2) said interpolation value calculation section selects a direction along which pixels having color information to be used to calculate said local curvature information are set based upon results of a judgment made by said second similarity judgment section if said local curvature information is “local curvature information constituted of a single color component and manifesting directionality along a direction in which degrees of similarity are judged by said second similarity judgment section.” 
   
     
     
         31 . An interpolation processing apparatus according to  claim 30 , wherein: 
 when image data are provided in a colorimetric system constituted of first˜third color components with the first color component achieving a higher spatial frequency than the second color component and the third color component, the first color component set in a checker-board pattern, the second color component and the third color component each set in a line sequence between pixels at which color information corresponding to the first color component is present and information corresponding to the second color component present at the interpolation target pixel;    said first similarity judgment section calculates similarity degrees manifested by the interpolation target pixel along two directions, i.e., a vertical direction and a horizontal direction, in which pixels with color information corresponding to the first color component that are closest to the interpolation target pixel are connected to the interpolation target pixel and makes a judgment with regard to degrees of similarity manifested by the interpolation target pixel along the vertical direction and the horizontal direction based upon a difference between said similarity degrees;    said second similarity judgment section calculates similarity degrees manifested by the interpolation target pixel along two diagonal directions in which pixels with color information corresponding to the third color component that are closest to the interpolation target pixel are connected to the interpolation target pixel and makes a judgment with regard to degrees of similarity manifested by the interpolation target pixel along the two diagonal directions based upon a difference between said similarity degrees; and    said interpolation value calculation section selects at least either the second color component or the first color component based upon which said “local curvature information constituted of a single color component and manifesting directionality along a direction in which degrees of similarity are judged by said first similarity judgment section” is provided and selects at least either the second color component or the third color component based upon which said “local curvature information constituted of a single color component and manifesting directionality along a direction in which degrees of similarity are judged by said second similarity judgment section” is provided.    
     
     
         32 . An interpolation processing apparatus according to  claim 31 , wherein: 
 when said local curvature information is “local curvature information based upon a color component other than the color component at the interpolation target pixel”, said interpolation value calculation section selects the first color component or the third color component to which said local curvature information is to correspond in conformance to the degrees of similarity judged by said second similarity judgment section.    
     
     
         33 . An interpolation processing apparatus according to  claim 32 , wherein: 
 said interpolation value calculation section calculates local curvature information based upon the first color component if said second similarity judgment section judges that roughly equal degrees of similarity manifest along the two diagonal directions and calculates local curvature information based upon the third color component if said second similarity judgment section judges that a higher degree of similarity manifests along one of the two diagonal directions compared to the other diagonal direction.    
     
     
         34 . An interpolation processing apparatus according to  claim 31 , wherein: 
 said first similarity judgment section judges that roughly equal degrees of similarity manifest along the vertical direction and the horizontal direction if a difference between the similarity degrees along the vertical direction and the horizontal direction is smaller than a specific threshold value; and    said second similarity judgment section judges that roughly equal degrees of similarity manifest along the two diagonal directions if a difference between the similarity degrees along the two diagonal directions is smaller than a specific threshold value.    
     
     
         35 . An interpolation processing apparatus according to  claim 31 , wherein: 
 said first similarity judgment section calculates the similarity degrees along the vertical direction and the horizontal direction by using color information corresponding to a plurality of color components for a single interpolation target pixel; and    said second similarity judgment section calculates the similarity degrees along the two diagonal directions by using color information corresponding to a plurality of color components for a single interpolation target pixel.    
     
     
         36 . An interpolation processing apparatus according to  claim 35 , wherein: 
 said second similarity judgment section calculates a similarity degree manifesting along each of the two diagonal directions through weighted addition of: 
 (1) a similarity degree component constituted of color information corresponding to the first color component alone;  
 (2) a similarity degree component constituted of color information corresponding to the second color component alone;  
 (3) a similarity degree component constituted of color information corresponding to the third color component alone; and  
 (4) a similarity degree component constituted of color information corresponding to the second color component and the third color component.  
   
     
     
         37 . An interpolation processing apparatus according to  claim 31 , wherein: 
 said first similarity judgment section calculates similarity degrees along the vertical direction and the horizontal direction for each pixel and makes a judgment on similarity manifested by the interpolation target pixel along the vertical direction and the horizontal direction based upon differences in similarity degrees manifesting at nearby pixels as well as at the interpolation target pixel; and    said second similarity judgment section calculates similarity degrees along the two diagonal directions for each pixel and makes a judgment on similarity manifested by the interpolation target pixel along the two diagonal directions based upon differences in similarity degrees manifesting at nearby pixels as well as at the interpolation target pixel.    
     
     
         38 . An interpolation processing apparatus according to any one of  claim 3 , further comprising: 
 a first similarity judgment section that judges degrees of similarity to the interpolation target pixel along at least two directions in which pixels with color information corresponding to the first color component are connected with the interpolation target pixel; and    a second similarity judgment section that judges degrees of similarity to the interpolation target pixel along at least two directions other than the directions in which the degrees of similarity are judged by said first similarity judgment section, wherein:    said interpolation value calculation section selects a direction along which pixels having color information to be used to calculate said local average information of the first color component are set based upon results of a judgment made by said first similarity judgment section; 
 (1) said interpolation value calculation section selects a direction along which pixels having color information to be used to calculate said local curvature information are set based upon results of the judgment made by said first similarity judgment section if said local curvature information is “local curvature information constituted of a single color component and manifesting directionality along a direction in which degrees of similarity are judged by said first similarity judgment section”; and  
 (2) said interpolation value calculation section selects a direction along which pixels having color information to be used to calculate said local curvature information are set based upon results of a judgment made by said second similarity judgment section if said local curvature information is “local curvature information constituted of a single color component and manifesting directionality along a direction in which degrees of similarity are judged by said second similarity judgment section.” 
   
     
     
         39 . An interpolation processing apparatus according to  claim 18 , wherein: 
 when the luminance component in the image data corresponds to a green color component and the color component in the image data corresponds to a red color component and a blue color component,    said hue value interpolation section calculates a hue value for the interpolation target pixel by using a median of hue values containing the red color component at pixels near the interpolation target pixel if the green color component is present but the red color component is missing at the interpolation target pixel and calculates a hue value for the interpolation target pixel by using a median of hue values containing the blue color component at pixels near the interpolation target pixel if the green color component is present but the blue color component is missing at the interpolation target pixel.    
     
     
         40 . An interpolation processing apparatus according to  claim 18 , wherein: 
 when the luminance component in the image data corresponds to a green color component and the color component in the image data corresponds to a red color component and a blue color component,    said hue value interpolation section calculates a hue value for the interpolation target pixel by using a median of hue values containing the red color component at pixels set near the interpolation target pixel if the blue color component is present but the red color component is missing at the interpolation target pixel.    
     
     
         41 . An interpolation processing apparatus according to  claim 18 , wherein: 
 when the luminance component in the image data corresponds to a green color component and the color component in the image data corresponds to a red color component and a blue color component,    said hue value interpolation section calculates a hue value for the interpolation target pixel by using a median of hue values containing the blue color component at pixels set near the interpolation target pixel if the red color component is present but the blue color component is missing at the interpolation target pixel.    
     
     
         42 . An interpolation processing apparatus according to  claim 18 , with a color component missing at the interpolation target pixel present at only one pixel among four pixels set symmetrically along the vertical direction and the horizontal direction, wherein said hue value interpolation section comprises: 
 a first hue value interpolation unit that calculates a hue value for the interpolation target pixel by using a median of hue values at a plurality of diagonally adjacent pixels if the hue values of the plurality of diagonally adjacent pixels adjacent to the interpolation target pixel along diagonal directions have been calculated by said hue value calculation section; and    a second hue value interpolation unit that calculates a hue value for the interpolation target pixel by using a median of hue values at a plurality of vertically and horizontally adjacent pixels if the hue values of the plurality of vertically and horizontally adjacent pixels adjacent to the interpolation target pixel in the vertical direction and the horizontal direction have been calculated by said hue value calculation section or said first hue value interpolation unit.