Edge generation method, edge generation device, medium recording edge generation program, and image processing method

Abstract

A direction of an intended edge is determined, and a position of the intended edge is corrected to a position that brings a direction that connects a position of the intended edge and a position of an adjacent edge closer to the determined direction of the intended edge, and edge information representative of an area of the edge of an enlarged image is generated by using the corrected position of the edge. Gradation data before and after filtering are synthesized at a rate corresponding to a feature quantity representative of the amount of pixels within a predetermined color area. The gradation data of the plural pixels within a predetermined region including the position of the intended edge to be sharpened among the interpolated gradation data of the respective pixels on the interpolated image is sharpened at a degree corresponding to the number of pixels of the uninterpolated image.

1 . An edge generation method that generates edge information which expresses an area of an edge of an enlarged image resulting from enlarging an unenlarged image on the basis of image data that represents the unenlarged image with gradation data of each pixel, the method comprising:
 acquiring a position of an edge in correspondence with a position of each pixel of the enlarged image on the basis of the image data;   determining a direction of an intended edge according to the gradation data of plural pixels within a predetermined region including the position of the intended edge which determines the direction among the gradation data of each pixel on the enlarged image;   correcting the position of the intended edge to a position that brings a direction connecting a position of the intended edge and a position of an edge that is in proximity to the intended edge closer to the determined direction of the intended edge in the enlarged image;   generating the edge information representative of the area of the edge of the enlarged image in correspondence with the position of each pixel of the enlarged image;   interpolating the intended pixel to generate interpolated gradation data by using the image data of the plural pixels on the unenlarged image which are positioned in proximity to the intended pixel whose gradation data is to be interpolated; and   sharpening the gradation data of the plural pixels within the predetermined region including the position of the intended edge to be sharpened among the gradation data of the respective pixels which has been interpolated on the interpolated image at a degree corresponding to the number of pixels of the uninterpolated image.   
   
   
       2 . An image processing method that sharpens an edge portion by interpolating image data that expresses an uninterpolated image by plural pixels in gradation to generate gradation data corresponding to each of the pixels of the interpolated image, the method comprising:
 acquiring a position of the edge corresponding to a position of each pixel of the interpolated image on the basis of the image data;   interpolating the intended pixel by using the image data of the plural pixels on the uninterpolated image which are positioned in proximity to the intended pixel to be interpolated on the interpolated image to generate interpolated gradation data; and   sharpening the gradation data of the plural pixels within the predetermined region including the position of the intended edge to be sharpened among the interpolated gradation data of the respective pixels on the interpolated image at a degree corresponding to the number of pixels of the uninterpolated image.   
   
   
       3 . The image processing method according to  claim 2 , wherein, in sharpening the gradation data, the degree of sharpness of the uninterpolated image having a first pixel number is larger than the degree of sharpness of the uninterpolated image having a second pixel number that is smaller than the first pixel number. 
   
   
       4 . The image processing method according to  claim 2 , wherein sharpening the gradation data comprises: conducting predetermined sharpening operation on the gradation data of the plural pixels within the predetermined region to obtain sharpened gradation data; and synthesizing the gradation data that has not yet been subjected to the sharpening operation and the gradation data that has been subjected to the sharpening operation with respect to the plural pixels within the predetermined region at the rate corresponding to the number of pixels of the uninterpolated image into sharpened gradation data. 
   
   
       5 . The image processing method according to  claim 2 , wherein sharpening the gradation data comprises, provided that the gradation value of each pixel within the predetermined region is g 1 , the gradation value that has been subjected to sharpening operation is g 2 , the minimum of luminance values of the plural pixels within the predetermined region is min, the maximum of the luminance values is max, and an average value of the luminance values is ave, and predetermined coefficients corresponding to the number of pixels of the uninterpolated image are a 1  and a 2  (0<a 1 <1<a 2 ), sharpening the gradation data of the plural pixels within the predetermined region at a degree corresponding to the number of pixels of the uninterpolated image by using the following arithmetic expressions:
 (A) Where g 1  is equal to or smaller than [(1−a 1 )×min−(1−a 2 )×ave]/(a 2 −a 1 )],
     g 2= a 1× g 1+(1− a 1)×min 
   (B) Where g 1  is equal to or larger than [(1−a 1 )×min−(1−a 2 )×ave]/(a 2 −a 1 )], and g 1  is equal to or smaller than [(1−a 1 )×max−(1−a 2 )×ave]/(a 2 −a 1 )],
     g 2= a 2× g 1+(1− a 2)×ave 
   (C) Where g 1  is equal to or larger than [(1−a 1 )×max−(1−a 2 )×ave]/(a 2 −a 1 )],
     g 2= a 1× g 1+(1− a 1)×max. 
   
   
   
       6 . The image processing method according to  claim 2 , wherein sharpening the gradation data comprises: conducting predetermined sharpening operation on the gradation data of the plural pixels within the predetermined region to obtain the gradation data that has been subjected to the sharpening operation; obtaining gradation data that averages the already obtained gradation data that has been subjected to the sharpening operation and newly obtained gradation data that has been subjected to the sharpening operation with respect to the pixels whose gradation data has been already subjected to the sharpening operation among the plural pixels within the predetermined region; and sharpening the gradation data of the plural pixels within the predetermined region by the obtained gradation data at a degree corresponding to the number of pixels of the uninterpolated image. 
   
   
       7 . The image processing method according to  claim 2 , wherein sharpening the gradation data comprises: setting the position of the intended edge except for the position of the edge adjacent to the edge which was the position of the intended edge where the position of the intended edge is sequentially set among the positions of the edges that are acquired by the interpolated position acquiring processor. 
   
   
       8 . The image processing method according to  claim 2 , wherein interpolating the intended pixel to generate interpolated gradation data comprises: conducting the interpolating process by using only the image data of the pixels which is different within a predetermined range from the image data of the pixel corresponding to the intended pixel among the plural pixels in the uninterpolated image that is positioned in vicinity to the intended pixel to generate the interpolated gradation data. 
   
   
       9 . An image processing method that sharpens an edge portion by interpolating image data that expresses an uninterpolated image by plural pixels in gradation to generate gradation data corresponding to each of the pixels of an enlarged image obtained by enlarging the unenlarged image, the method comprising:
 acquiring enlarged edge position information representative of a position of the edge by a unit smaller than the pixel of the enlarged image;   interpolating the intended pixel by using the image data of the plural pixels on the unenlarged image which are positioned in proximity to the intended pixel to be interpolated on the enlarged image to generate interpolated gradation data; and   after the interpolating has been conducted, sharpening the gradation data of the plural pixels within the predetermined region including the position of the intended edge among the interpolated gradation data of the respective pixels on the enlarged image while the position of the intended edge is sequentially set with reference with the enlarged edge position information that is represented by a unit smaller than the pixels of the unenlarged image.