用canvas实现图片滤镜效果详解之视频效果

 

               pattern = [ 

                   0, 1, 

                   0, 2, 

                   1, 2, 

                   1, 0, 

                   2, 0, 

                   2, 1, 

               ]; 

               break; 

           } 

           case1://VIDEO_TYPE.VIDEO_TRIPED: 

           { 

               pattern = [   

                   0, 

                   1, 

                   2, 

               ]; 

               break; 

           } 

           case2://VIDEO_TYPE.VIDEO_3X3: 

           { 

               pattern = 

               [ 

                   0, 1, 2, 

                   2, 0, 1, 

                   1, 2, 0, 

               ]; 

               break; 

           } 

           default: 

           { 

               pattern = 

               [ 

                   0, 1, 2, 0, 0, 

                   1, 1, 1, 2, 0, 

                   0, 1, 2, 2, 2, 

                   0, 0, 1, 2, 0, 

                   0, 1, 1, 1, 2, 

                   2, 0, 1, 2, 2, 

                   0, 0, 0, 1, 2, 

                   2, 0, 1, 1, 1, 

                   2, 2, 0, 1, 2, 

                   2, 0, 0, 0, 1, 

                   1, 2, 0, 1, 1, 

                   2, 2, 2, 0, 1, 

                   1, 2, 0, 0, 0, 

                   1, 1, 2, 0, 1, 

                   1, 2, 2, 2, 0, 

               ]; 

               break; 

           } 

       } 

       var pattern_width = [ 2, 1, 3, 5 ]; 

       var pattern_height = [6, 3, 3, 15 ];

　　

3.获取过滤数据

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for ( var x = 0; x < canvasData.width; x++) {             for ( var y = 0; y < canvasData.height; y++) {                         // Index of the pixel in the array               var idx = (x + y * canvasData.width) * 4;               var r = canvasData.data[idx + 0];               var g = canvasData.data[idx + 1];               var b = canvasData.data[idx + 2];                  var nWidth = pattern_width[m_VideoType];                var nHeight = pattern_height[m_VideoType];                var index = nWidth * (y % nHeight) + (x % nWidth);                    index = pattern[index];                if (index == 0)                 var   r = fclamp0255(2 * r);                if (index == 1)                 var   g = fclamp0255(2 * g);                if (index == 2)                 var   b = fclamp0255(2 * b);                                    // assign gray scale value                canvasData.data[idx + 0] = r; // Red channel                canvasData.data[idx + 1] = g; // Green channel                canvasData.data[idx + 2] = b; // Blue channel                canvasData.data[idx + 3] = 255; // Alpha channel                // 加上黑色的边框                if(x < 8 || y < 8 || x > (canvasData.width - 8) || y > (canvasData.height - 8))                 {                  canvasData.data[idx + 0] = 0;                  canvasData.data[idx + 1] = 0;                  canvasData.data[idx + 2] = 0;                }             }        }

　　

4.写入过滤后的数据

1	context.putImageData(canvasData, 0, 0);

　　

5.效果预览

点击这里预览

5.参考资料

代震军ImageFilter开源项目