Image converting method and image converting apparatus

Abstract

An image converting apparatus has: a parameter setting unit which sets parameters for converting each pixel of an input image into predetermined chromaticity coordinate values; a chromaticity coordinate converting unit which obtains conversion chromaticity coordinate values obtained by converting each pixel by the set parameters; a color region obtaining unit which obtains a color region including 2-dimensional conversion chromaticity coordinate values obtained by projecting each conversion chromaticity coordinate value onto a unit plane; an area calculation processing unit which calculates an area of the color region obtained every parameter and obtains parameter values at the time of the maximum area value; and an image converting unit which converts the input image by the parameter values. The image data unbalanced in color arrangement of an object is converted into image data obtained under an ideal white light source.

What is claimed is:  
     
         1 . An image converting method comprising the steps of: 
 converting chromaticity coordinate values which each pixel of an input image consisting of a plurality of pixels has into a 2-dimensional chromaticity coordinate plane and obtaining 2-dimensional conversion chromaticity coordinate values of each pixel;    obtaining an outline of a color region defined by the 2-dimensional conversion chromaticity coordinate values of said plurality of pixels converted into said 2-dimensional chromaticity coordinate plane;    obtaining 2-dimensional conversion chromaticity coordinate values, on a 2-dimensional chromaticity coordinate plane, of a barycenter of an area of a region which is specified by the outline of said color region; and    executing a color conversion of the input image by using the 2-dimensional conversion chromaticity coordinate values of said barycenter as a new coordinate origin.    
     
     
         2 . An image converting method comprising the steps of: 
 converting each pixel of an input image into 2-dimensional conversion chromaticity coordinate values which are obtained by projecting conversion chromaticity coordinate values obtained by converting each of said pixels by using parameters for converting in chromaticity coordinates onto a unit plane, and in a color region including said 2-dimensional conversion chromaticity coordinate values, obtaining parameter values in which an area of said color region becomes the maximum; and    converting said input image by said obtained parameter values.    
     
     
         3 . An image converting method comprising the steps of: 
 converting each pixel of an input image into 2-dimensional conversion chromaticity coordinate values which are obtained by projecting conversion chromaticity coordinate values obtained by converting each of said pixels by using parameters for converting in chromaticity coordinates onto a unit plane, and obtaining parameter values in which a barycenter of a color region including said 2-dimensional conversion chromaticity coordinate values is set to ⅓; and    converting the input image by said obtained parameter values.    
     
     
         4 . The method according to  claim 3 , wherein the parameter values at the time when the barycenter lies within a predetermined threshold value including ⅓ are obtained.  
     
     
         5 . An image converting apparatus comprising: 
 a parameter setting unit which sets parameters for converting each pixel of an input image into predetermined chromaticity coordinate values;    a chromaticity coordinate converting unit which obtains conversion chromaticity coordinate values obtained by converting each of said pixels on the basis of the parameters set by said parameter setting unit;    a color region obtaining unit which obtains a color region including 2-dimensional conversion chromaticity coordinate values obtained by projecting each of said conversion chromaticity coordinate values onto a unit plane;    an area calculation processing unit which calculates an area of said color region with respect to the parameters and obtains parameter values at the time when a value of the calculated area becomes the maximum; and    an image converting unit which converts said input image on the basis of the obtained parameter values.    
     
     
         6 . An image converting apparatus comprising: 
 a parameter setting unit which sets parameters for converting each pixel of an input image into predetermined chromaticity coordinate values;    a chromaticity coordinate converting unit which obtains conversion chromaticity coordinate values obtained by converting each of said pixels on the basis of the parameters set by said parameter setting unit;    a color region obtaining unit which obtains a color region including 2-dimensional conversion chromaticity coordinate values obtained by projecting each of said conversion chromaticity coordinate values onto a unit plane so that additive color mixture can be performed;    a barycenter calculation processing unit which calculates a barycenter of said color region with respect to the parameters and obtains parameter values at the time when the calculated barycenter is set to ⅓; and    an image converting unit which converts said input image on the basis of the obtained parameter values.    
     
     
         7 . The apparatus according to  claim 6 , wherein said barycenter calculation processing unit obtains the parameter values at the time when the barycenter lies within a predetermined threshold value including ⅓.