针对现有圆的反走样生成算法计算复杂,反走样效果一般的缺点,提出一种基于中点画圆法的整数反走样生成算法。该算法根据像素中心到理想圆弧的距离来分配灰度,生成64级灰度的反走样圆弧。通过省略二次项来简化计算,并用简单的计算修正省略带来的误差以保证精度。为了简化计算,提出相邻像素的灰度递推方法,利用整数移位、加法、比较来实现反走样。该算法结构简单,反走样效果较好,由于避免了浮点和除法运算,便于硬件实现。

Anti-aliasing for circles is complex and the existing algorithms are not working satisfactory.To improve the efficiency and the anti-aliasing effect,an integral algorithm is presented for circle anti-aliasing based on midpoint generating algorithm.The new algorithm finds the grayscales of each pixel according to the distance between the center of the pixel and the circle.A circle with a 64 levels grayscale can be drawn.The algorithm abandons the two-order epsilon and corrects the error by simple calculations.We built a method to forecast the grayscale change between neighboring pixels using integer shift,addition,and comparing without using floating-point and divisions,making it easy to implement the algorithm on hardware.The results show that the anti-aliasing effect and its efficiency have been improved.