艺术效果水泡
通过对图像进行变形或叠加其他图片，能够实现许多有趣的艺术效果，本文介绍类似水泡效果的实现方式，下面先看一下实现的效果。
第一张为原始图像，第二张为叠加水泡效果的图像。
cat.jpg
cat_belb.jpg
算法原理
图像中的水泡效果，是由两个算法叠加而成。第一个为计算水泡上反射光照的效果，第二个为图像通过水泡折射后的形变计算。
(1)光照效果实现
通过设定光源的位置，及水泡上个点与光源的位置关系进行计算，下面是实现代码：
public static void upLightPoint(BufferedImage image, int x, int y, double scale, double hall) {
Pixel pixel = new Pixel();
if (scale > 1)
scale = 1;
else if (scale < 0) {
if (hall == 0) {
scale = 0;
} else {
scale = scale / hall;
}
}
pixel.setRGB(image.getRGB(x, y));
if (scale >= 0) {
pixel.red = pixel.red + (int) ((255 - pixel.red) * scale);
pixel.green = pixel.green + (int) ((255 - pixel.green) * scale);
pixel.blue = pixel.blue + (int) ((255 - pixel.blue) * scale);
} else {
pixel.red = pixel.red + (int) (pixel.red * scale);
pixel.green = pixel.green + (int) (pixel.green * scale);
pixel.blue = pixel.blue + (int) (pixel.blue * scale);
}
image.setRGB(x, y, pixel.getRGB());
}
public static void drawBall(BufferedImage bimg, int x_center, int y_center, int radius, int x_lamp, int y_lamp) {
double z, z_lamp;
double distance;
for (int y = y_center - radius; y < y_center + radius; y++) {
for (int x = x_center - radius; x < x_center + radius; x++) {
distance = (x - x_center) * (x - x_center) + (y - y_center) * (y - y_center);
if (distance > radius * radius)
continue;
z = Math.sqrt(radius * radius - distance);
z_lamp = Math.sqrt(radius * radius - (x_lamp - x_center) * (x_lamp - x_center)
- (y_lamp - y_center) * (y_lamp - y_center));
distance = Math.sqrt(radius * radius * 2 - 2 * (x - x_center) * (x_lamp - x_center)
- 2 * (y - y_center) * (y_lamp - y_center) - 2 * z * z_lamp);
try {
upLightPoint(bimg, x, y, (1 - distance / radius / .5), 0);
} catch (Exception e) {
}
}
}
}
(2)折射效果实现
通过背景图像图水泡中心的位置关系，计算简单的折射效果，代码如下：
public static void belbImage(BufferedImage image, BufferedImage bimg, int x_center, int y_center, int radius) {
double scale = radius * Math.PI / 2;
double x1 = 0;
double y1 = 0;
for (int y = y_center - radius; y < y_center + radius; y++) {
for (int x = x_center - radius; x < x_center + radius; x++) {
double distance = Math.sqrt((x - x_center) * (x - x_center) + (y - y_center) * (y - y_center));
if (distance > radius)
continue;
double hu = Math.asin(distance / radius);
double v = hu * scale * 4.14 / 180.0;
x1 = x_center + (x - x_center) * v;
y1 = y_center + (y - y_center) * v;
try {
if (x1 > image.getWidth())
x1 = image.getWidth() * 2 - x1;
else if (x1 < 0)
x1 = -x1;
if (y1 > image.getHeight())
y1 = image.getHeight() * 2 - y1;
else if (y1 < 0)
y1 = -y1;
bimg.setRGB(x, y, image.getRGB((int) x1, (int) y1));
} catch (Exception e) {
}
}
}
}
(3)两种效果的叠加
将两种效果进行叠加，就产生了水泡的效果，叠加代码如下：
public static BufferedImage drawBallImage(BufferedImage image, int x, int y, int radius) {
BufferedImage bimg = new BufferedImage(image.getWidth(), image.getHeight(), BufferedImage.TYPE_INT_RGB);
Graphics2D g2 = bimg.createGraphics();
g2.drawImage(image, 0, 0, null);
int r = radius, x_lamp, y_lamp;
x_lamp = x - (int) (r / 2.0);
y_lamp = y - (int) (r / 2.0);
belbImage(image, bimg, x, y, r);
drawBall(bimg, x, y, r, x_lamp, y_lamp);
g2 = bimg.createGraphics();
g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.0f));
g2.drawImage(image, 0, 0, null);
g2.dispose();
return bimg;
}
代码中使用到的辅助类Pixel代码如下：
import java.awt.image.*;
public class Pixel {
public int red;
public int green;
public int blue;
public int alpha=0xFF;
public double hue;
public double saturation;
public double luminosity;
private int rgb;
public Pixel() {
}
public void setRGB(int rgb) {
red = (rgb & 0x00FF0000) / 0x00010000;
green = (rgb & 0x0000FF00) / 0x00000100;
blue = rgb & 0x000000FF;
alpha = (rgb >> 24)&0x0ff;
this.rgb = rgb;
}
public int getRGB() {
rgb = alpha<<24 | 0x00010000 * red | 0x00000100 * green | blue;
return this.rgb;
}
public static void setRgb(BufferedImage image, int x, int y, int red, int green, int blue) {
int rgb = 0xFF000000 | red * 0x00010000 | green * 0x00000100 | blue;
image.setRGB(x, y, rgb);
}
public static int pixelIntensity(int rgb) {
int red = (rgb&0x00FF0000)/0x00010000;
int green = (rgb&0x0000FF00)/0x00000100;
int blue = rgb&0x000000FF;
return (int) (0.299 * red + 0.587 * green + 0.114 * blue + 0.5);
}
}
测试代码
本文上的效果图片使用了下面的测试代码：
public static void main(String[] argv) throws IOException {
BufferedImage img = read(new File("cat.jpg"));
BufferedImage img2 =drawBallImage(img, 100, 300, 80);
ImageIO.write(img2, "jpeg", new File("cat_belb.jpg"));
}
