图像特效------三角几何应用 分类： 视频图像处理 2015-07-24 10:06 37人阅读 评论(0) 收藏

一：基本的三角函数知识






同样根据a, b的值可以计算出角度θ值，称之为反三角函数，角度θ=atan2(a, b)

图像处理中应用三角函数常常把中心点设置为A点，任意像素点B到A的距离可以根据三

角函数来计算得出，常见的计算模型如下：



对待求像素点加以一定三角函数变化，可以实现很多意想不到的图形特效，中心像素点可以

通过以下计算获得

int centerX = width/2;

int centerY = height/2;

扫描到的像素点p(x, y)可以基于 中心像素点，角度θ,两点之间距离Radius可以通过如

下计算获得：

int trueX = col -centerX;

int trueY = row -centerY;

theta = Math.atan2((trueY),(trueX));

radius = Math.sqrt(trueX*trueX + trueY*trueY);

二：特效原理

实现的特效很简单，上述的三角几何中计算结果中，有两个可以改变其值再重新计算坐标

P(x,y)。一个是角度，另外一个是半径距离，分别对角度与距离加以一定权重值计算，得到

如下两种特效：

1. 哈哈镜效果，主要是改变半径值，计算方法如下：

double newRadius = Math.sqrt(radius) * factor;

newX = centerX + (newRadius * Math.cos(theta));

newY = centerY + (newRadius * Math.sin(theta));

其中factor为输入参数

2. 中心螺旋效果，主要是改变角度θ的值，计算方法如下：

newX = centerX + (radius * Math.cos(theta+degree * radius));

newY = centerY + (radius * Math.sin(theta+degree * radius));

其中degree为输入参数.

三：程序效果

哈哈镜效果：



螺旋效果



两个滤镜程序的源代码如下：1. Magic Mirror

[java] view plaincopypackage com.process.blur.study;

import java.awt.image.BufferedImage;

public class MagicMirrorFilter extends AbstractBufferedImageOp {
private double factor = 15.0d; // default value

public MagicMirrorFilter() {

}

public MagicMirrorFilter(double factor) {
this.factor = factor;
}

public double getFactor() {
return factor;
}

public void setFactor(double factor) {
this.factor = factor;
}

@Override
public BufferedImage filter(BufferedImage src, BufferedImage dest) {
int width = src.getWidth();
int height = src.getHeight();

if ( dest == null )
dest = 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, outIndex = 0;
int centerX = width/2;
int centerY = height/2;
double theta, radius;
double newX, newY;
int offsetX = 0, offsetY = 0;
for(int row=0; row<height; row++) {
int ta = 0, tr = 0, tg = 0, tb = 0;
for(int col=0; col<width; col++) {

int trueX = col - centerX;
int trueY = row - centerY;
theta = Math.atan2((trueY),(trueX));
radius = Math.sqrt(trueX*trueX + trueY*trueY);
double newRadius = Math.sqrt(radius) * factor;
newX = centerX + (newRadius * Math.cos(theta));
newY = centerY + (newRadius * Math.sin(theta));

if (newX > 0 && newX < width) {
offsetX = (int)newX;
} else {
newX = 0;
}

if (newY > 0 && newY < height) {
offsetY = (int)newY;
} else {
newY = 0;
}

index = offsetY * width + offsetX;
ta = (inPixels[index] >> 24) & 0xff;
tr = (inPixels[index] >> 16) & 0xff;
tg = (inPixels[index] >> 8) & 0xff;
tb = inPixels[index] & 0xff;

// use newX, newY and fill the pixel data now...
outIndex = row * width + col;
outPixels[outIndex] = (ta << 24) | (tr << 16) | (tg << 8) | tb;
}
}

setRGB( dest, 0, 0, width, height, outPixels );
return dest;
}

}
2. Swirl
[java] view plaincopypackage com.process.blur.study;

import java.awt.image.BufferedImage;

public class SwirlFilter extends AbstractBufferedImageOp{

// recommended scope is [0.1 ~ 0.001]
private double degree = 0.02d; // default value,

public SwirlFilter() {

}

public double getDegree() {
return degree;
}

public void setDegree(double degree) {
this.degree = degree;
}

@Override
public BufferedImage filter(BufferedImage src, BufferedImage dest) {
int width = src.getWidth();
int height = src.getHeight();

if ( dest == null )
dest = 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, outIndex = 0;
int centerX = width/2;
int centerY = height/2;
double theta, radius;
double newX, newY;
int offsetX = 0, offsetY = 0;
for(int row=0; row<height; row++) {
int ta = 0, tr = 0, tg = 0, tb = 0;
for(int col=0; col<width; col++) {

int trueX = col - centerX;
int trueY = row - centerY;
theta = Math.atan2((trueY),(trueX));
radius = Math.sqrt(trueX*trueX + trueY*trueY);

// the top trick is to add (degree * radius), generate the swirl effect...
newX = centerX + (radius * Math.cos(theta + degree * radius));
newY = centerY + (radius * Math.sin(theta + degree * radius));

if (newX > 0 && newX < width) {
offsetX = (int)newX;
} else {
offsetX = col;
}

if (newY > 0 && newY < height) {
offsetY = (int)newY;
} else {
offsetY = row;
}

index = offsetY * width + offsetX;
ta = (inPixels[index] >> 24) & 0xff;
tr = (inPixels[index] >> 16) & 0xff;
tg = (inPixels[index] >> 8) & 0xff;
tb = inPixels[index] & 0xff;

// use newX, newY and fill the pixel data now...
outIndex = row * width + col;
outPixels[outIndex] = (ta << 24) | (tr << 16) | (tg << 8) | tb;
}
}

setRGB( dest, 0, 0, width, height, outPixels );
return dest;
}

}