1. A method of generating ink amount data which is the used amounts of inks of respective colors when an image is printed, by analyzing image data of the image, the method comprising: extracting a character area, of which a saturation value is equal to or less than a predetermined value, from the image by analyzing the image data; dividing the character area into a character contour area which is a contour part of the character and a character inside area which is the inside of the character; and converting the image data of the character contour area and the image data of the character inside area into the ink amount data of at least one type of achromatic color ink and at least three types of chromatic color inks, wherein the converting of the ink amount data includes converting the image data of the areas into the ink amount data such that the chromatic color inks are largely used in the character inside area compared with the character contour area.