168 471 Computer Graphics, KKU. Lecture 9 Antialiasing jaggies digitized Analog line Digital line: aliasing occurs Aliased 'W' Antialiased 'W' 168 471 Computer Graphics, KKU. Lecture 9

168 471 Computer Graphics, KKU. Lecture 9 Antialiasing What anti-aliasing attempts to do is, using mathematics, fill in some of the digital system with colors that are in-between the two adjoining colors. In this case a medium gray would be between the black and the white. Some gray squares placed in the grid might help soften up the "jaggies" 168 471 Computer Graphics, KKU. Lecture 9

168 471 Computer Graphics, KKU. Lecture 9 Antialiasing 168 471 Computer Graphics, KKU. Lecture 9

Unweighted Area Sampling Intensity is proportional to the amount of area covered. Defining the box weighting function which has volume of 1 (Imax). Determine the overlap volume Ws [0, 1]. 168 471 Computer Graphics, KKU. Lecture 9

Weighted Area Sampling 168 471 Computer Graphics, KKU. Lecture 9

Antialiasing in Practice Use of low pass filter by summing products between the mask coefficients and the intensities of the pixels under the mask. For w which is a 3x3 mask, the response R at the center of the mask is R = w1z1 + w2z2 + … + w9z9 mask R mask R 168 471 Computer Graphics, KKU. Lecture 9

Antialiasing in Practice (b) 168 471 Computer Graphics, KKU. Lecture 9