1. An information processing device comprising: an acquisition unit to acquire an image; a first division unit to divide the image into a text containing region containing one or more characters and a background region other than the text containing region; a second division unit to divide the text containing region into a character region constituted by lines forming the characters and a character background region other than the character region; a calculator to calculate a first representative value of a predetermined attribute of the character region, a second representative value of the predetermined attribute of the character background region, and a third representative value of the predetermined attribute of the background region; a modification unit to modify at least one of the first representative value, the second representative value, and the third representative value in such a way that a first difference based on the first representative value and the third representative value, a second difference based on the first representative value and the second representative value, and a third difference based on the second representative value and the third representative value become larger; and an output unit to output a modified image obtained by changing the value of the predetermined attribute of the character region to a modified first representative value when the first representative value is modified, changing the value of the predetermined attribute of the character background region to a modified second representative value when the second representative value is modified, or changing the value of the predetermined attribute of the background region to a modified third representative value when the third representative value is modified.