1. A method of converting colorimetric values defined in a uniform color space into the amounts of print color materials of cyan, magenta, yellow, and black, comprising the steps of: a) converting the amounts of black color material and the colorimetric values to m sets of print color materials of cyan, magenta, and yellow on the basis of predetermined m (1&lt;m) amounts of print color material of black; b) calculating a range of print color material of each of cyan, magenta, and yellow in which the amount of print color material of each of cyan, magenta, and yellow is not less than 0% and not more than 100%, on the basis of the m sets of print color materials of cyan, magenta, and yellow obtained in the step a); c) obtaining a common range of the amounts of print color material of black from the range of print color material of each of cyan, magenta, and yellow calculated in the step b); d) multiplying a maximum value in the common range of the amounts of print color material of black by a predetermined coefficient n (0.ltoreq.n.ltoreq.1), determining the product as the amount of print color material of black if the product is larger than a minimum value in the range of the amounts of print color material of black, and determining the minimum value as the amount of print color material of black if the product is smaller than the minimum value; and e) converting the amount of print color material of black obtained in the step d) and the colorimetric values into the amounts of print color materials of cyan, magenta, and yellow, and determining the obtained amounts of color materials of the respective colors as the amounts of print color materials of cyan, magenta, and yellow.