1. An image processing device comprising: a computing device having a processor, wherein the processor is programmed to function as: a first color detection means for detecting colors of first image data by each processing unit, said first image data including data of a plurality of foreground objects and grouping all of the detected colors of the plurality of foreground objects in the first image data into groups, each group containing a grouping of approximately equal colors from the plurality of foreground objects; a second color detection means for detecting colors of second image data that serves as the first image data's background by each processing unit, the second image data having a plurality of different colors; and means for comparing, for each group, a representative color that is determined from the approximately equal colors of the group, to all the colors of the second image data that are adjacent to the first image data of the group and for specifying a single uniform adjusting color to be used for the group, that makes the first image data recognizable against all colors of the second image data that serve as the first image data's background; wherein the computing device includes: a first memory means for storing the colors of the first image data by each of the approximately equal colors; and a second memory means for storing the colors of the second image data that serves as the first image data's background, said colors of which are correlated to each of the corresponding colors of the first image data that are stored in said first memory means; wherein said comparing and specifying means includes: an average color value calculating means for calculating an average value of all the colors of the second image data and for each group an average value of all the colors in each group as the representative color, the average value of all the colors of the second image data being correlated to each of the representative colors of the first image data; and an adjusting color calculating means for calculating said adjusting color for each of the colors of the first image data based on each of the representative colors of the first image data and the average color value of the second image data calculated in correspondence with each of the representative colors of the first image data.