图像特效------三角几何应用

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

package 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
            int ta = 0, tr = 0, tg = 0, tb = 0;
            for(int col=0; 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

package 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
            int ta = 0, tr = 0, tg = 0, tb = 0;
            for(int col=0; 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;
    }

}