1.  Technical Field
The invention relates to an image processing apparatus, an image processing method and a computer-readable medium. 
2.  Description of the Related Art
For example, when a color image is to be printed with a monochrome printer, the color image is converted into a monochrome image.  Some technology for converting a color image into a monochrome image can convert a color image having 8 colors, 16 colors, or the like into a monochrome image with associating the colors with gray scale levels.  However, for a full color image in which 167.7 million or more colors can be designated, it is difficult to associate each color with a gray scale level.  Furthermore, even in the case where the colors are associated with gray scale levels, a user may not be able to recognize differences among the colors corresponding to the gray scale levels. 
As described above, it is difficult to uniformly convert a color image into a monochrome image such that a user can recognize differences among the colors.  Thus, for example, only one element of the color image such as brightness is focused on for the conversion of the color image into a monochrome image.  However, in such a case, if colors are difference in other elements such as hue and saturation but are the same in brightness, the colors are converted into the same gray scale level.