卷积模糊或者卷积平滑滤波,可以消除图像噪声,也可以产生一些常见的图像模糊特效,但
是移动模糊特效也是基于卷积,相比于Box Blur, Gaussian Blur的算法,移动模糊只需要完成
一次的一维卷积,所不同的是一维卷积的完成,要基于一定的角度,而不是只是在水平和垂
直两个方向上。移动模糊的一维卷积要考虑一下三个因素:
a. 操作数的多少 - 即距离(Distance)
b.一维操作数在像素数组中的移动方向 – 即角度(Angle)
c.一维操作数的拉影效应 – 即Scale(放大和缩小程度)(Zoom/Scale)
距离和角度的关系可以用三角几何表示如下:
假设距离和角度已知的情知道中心点(目标像素点)则可以求出每个操作数的像素点坐标,假
设中心点坐标为Base(x0, y0) 则操作数P(a, b)坐标公式可以表示如下:
a = sinx * c +y0
b = cosx * c +x0
放缩功能其实是在XY两个方向对图像计算得到一个一维像素结合,再求这些像素的平均值
即可,假设中心点像素为x0, y0, 防缩比率为s0则每个操作数像素点坐标可以表示为:
a= x0-x0 * s0 + a
b= y0-y0*so + b
原理部分的解释大概如此,下面来看一下,实际图像处理效果和源代码详细解释。
程序运行效果如下– 距离50个像素,角度 0 时:
角度30时候的滤镜运行结果:
放缩模糊效果:
角度,距离,放缩三个参数综合效果:
关键代码解释:
计算三角几何角度sin与cos值的代码如下:
- // calculate the trianglegeometry value
- float sinAngle = (float)Math.sin(angle/180.0f * onePI);
- float coseAngle = (float)Math.cos(angle/180.0f * onePI);
计算距离半径代码如下:
- // calculate the distance,same as box blur
- float imageRadius = (float)Math.sqrt(cx*cx + cy*cy);
- float maxDistance = distance + imageRadius * zoom;
计算操作数像素坐标的代码如下:
- // calculate the operatorsource pixel
- if(distance > 0) {
- newY = (int)Math.floor((newY+ i*sinAngle));
- newX = (int)Math.floor((newX + i*coseAngle));
- }
完成Scale的代码如下:
- // scale the pixels
- float scale = 1-zoom*f;
- m11 = cx - cx*scale;
- m22 = cy - cy*scale;
- newY = (int)(newY * scale +m22);
- newX = (int)(newX * scale + m11);
求取像素平均值,完成一维卷积的代码如下:
- // blur the pixels, here
- count++;
- int rgb= inPixels[newY*width+newX];
- ta += (rgb >> 24) & 0xff;
- tr += (rgb >> 16) & 0xff;
- tg += (rgb >> 8) & 0xff;
- tb += rgb & 0xff;
重新填充目标像素的代码如下:
- ta = clamp((int)(ta/count));
- tr = clamp((int)(tr/count));
- tg = clamp((int)(tg/count));
- tb = clamp((int)(tb/count));
- outPixels[index] = (ta << 24) | (tr<< 16) | (tg << 8) | tb;
移动模糊算法的完全源代码如下(不包含测试代码):
- package com.gloomyfish.process.blur.study;
- import java.awt.image.BufferedImage;
- public class MotionFilter {
- private float distance = 0;// default;
- private float onePI = (float)Math.PI;
- private float angle = 0.0f;
- private float zoom = 0.4f;
- public float getDistance() {
- return distance;
- }
- public void setDistance(float distance) {
- this.distance = distance;
- }
- public float getAngle() {
- return angle;
- }
- public void setAngle(float angle) {
- this.angle = angle;
- }
- public BufferedImage filter(BufferedImage src, BufferedImage dst) {
- int width = src.getWidth();
- int height = src.getHeight();
- if ( dst == null )
- dst = createCompatibleDestImage( src, null );
- int[] inPixels = new int[width*height];
- int[] outPixels = new int[width*height];
- getRGB( src, 0, 0, width, height, inPixels );
- int index = 0;
- int cx = width/2;
- int cy = height/2;
- // calculate the triangle geometry value
- float sinAngle = (float)Math.sin(angle/180.0f * onePI);
- float coseAngle = (float)Math.cos(angle/180.0f * onePI);
- // calculate the distance, same as box blur
- float imageRadius = (float)Math.sqrt(cx*cx + cy*cy);
- float maxDistance = distance + imageRadius * zoom;
- int iteration = (int)maxDistance;
- for(int row=0; row<height; row++) {
- int ta = 0, tr = 0, tg = 0, tb = 0;
- for(int col=0; col<width; col++) {
- int newX= col, count = 0;
- int newY = row;
- // iterate the source pixels according to distance
- float m11 = 0.0f, m22 = 0.0f;
- for(int i=0; i<iteration; i++) {
- newX = col;
- newY = row;
- // calculate the operator source pixel
- if(distance > 0) {
- newY = (int)Math.floor((newY + i*sinAngle));
- newX = (int)Math.floor((newX + i*coseAngle));
- }
- float f = (float)i/iteration;
- if (newX < 0 || newX >= width) {
- break;
- }
- if (newY < 0 || newY >= height) {
- break;
- }
- // scale the pixels
- float scale = 1-zoom*f;
- m11 = cx - cx*scale;
- m22 = cy - cy*scale;
- newY = (int)(newY * scale + m22);
- newX = (int)(newX * scale + m11);
- // blur the pixels, here
- count++;
- int rgb = inPixels[newY*width+newX];
- ta += (rgb >> 24) & 0xff;
- tr += (rgb >> 16) & 0xff;
- tg += (rgb >> 8) & 0xff;
- tb += rgb & 0xff;
- }
- // fill the destination pixel with final RGB value
- if (count == 0) {
- outPixels[index] = inPixels[index];
- } else {
- ta = clamp((int)(ta/count));
- tr = clamp((int)(tr/count));
- tg = clamp((int)(tg/count));
- tb = clamp((int)(tb/count));
- outPixels[index] = (ta << 24) | (tr << 16) | (tg << 8) | tb;
- }
- index++;
- }
- }
- setRGB( dst, 0, 0, width, height, outPixels );
- return dst;
- }
- public int clamp(int c) {
- if (c < 0)
- return 0;
- if (c > 255)
- return 255;
- return c;
- }
- }