1. A computerized automatic image drawing apparatus for grading a two dimensional image of an object, comprising: primitive forming means for dividing a two dimensional image having a peripheral outline, represented by two-dimensional image data, into a plurality of discrete two-dimensional primitives of predetermined shapes possessing a finite spread or area; grading means for dividing each of said selected plurality of two-dimensional primitives into a predetermined number of adjacent two dimensional sections, and grading at least one of the respective sections of each of said plurality of two-dimensional primitives by changing at least one of color, lightness and chromaticity thereof, according to predetermined conditions to obtain graded primitives; and displaying means for combining the graded primitives together to recreate said peripheral outline, and for displaying the combined primitives as a graded two-dimensional image or said object; the grading means selects a lightest first part and a darkest second part on one of the selected primitives, divides an intermediate area between the first and second parts into a plurality of sections, and sequentially colors the sections in order of lightness.