图像处理------透明混合 - Alpha Blending效果

基本原理：图像的透明混合有个专属名词– Alpha Blending 对任意两张图像可以合成为一张图像，合成图像的像素取值根据数学公式：RGB3 = (1- a) * RGB1 + a * RGB2其中a为混合透明度取值范围[0, 1]之间, RGB3为目标像素值, RGB1与RGB2的值分别来自两张不同的图像。
两张源图像分别为：


第二张源图像是房屋设计图


三：最终程序效果如下


四：程序关键代码及解释获取BufferedImage对象中像素数据的代码如下：[java] view plaincopypublic void getRGB(BufferedImage img, int x, int y, int width, int height, int[] pixelsData) {
int type = img.getType();
if (type == BufferedImage.TYPE_INT_ARGB || type == BufferedImage.TYPE_INT_RGB) {
img.getRaster().getDataElements(x, y, width, width, pixelsData);
} else {
img.getRGB(x, y, width, height, pixelsData, 0, img.getWidth());
}
}

将处理后的像素数组写到新创建的BufferedImage对象中的代码如下：[java] view plaincopypublic void setRGB(BufferedImage img, int x, int y, int width, int height, int[] pixelsData) {
int type = img.getType();
if (type == BufferedImage.TYPE_INT_ARGB || type == BufferedImage.TYPE_INT_RGB) {
img.getRaster().setDataElements(x, y, width, height, pixelsData);
} else {
img.setRGB(x, y, width, height, pixelsData, 0, width);
}
}

创建一个新BufferedImage对象代码如下：[java] view plaincopyalphaBlendingImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);

实现Alpha Blending的代码如下：[java] view plaincopyfloat blendingRate = 0.5f;
private void processPixels(int[] inPixelsOne, int[] inPixelsTwo, int[] outPixelsData, int width, int height) {
int index = 0;
for(int row=0; row<height; row++) {
for(int col=0; col<width; col++) {
int ta = 0, tr = 0, tg = 0, tb = 0;
int rgb1 = inPixelsOne[index];
int rgb2 = inPixelsTwo[index];
ta = ((rgb1 >> 24) & 0xff) + ((rgb2 >> 24) & 0xff);
tr = ((rgb1 >> 16) & 0xff) + ((rgb2 >> 16) & 0xff);
tg = ((rgb1 >> 8) & 0xff) + ((rgb2 >> 8) & 0xff);
tb = (rgb1 & 0xff) + (rgb2 & 0xff);

int a = 0, r=0, g=0, b=0;
a = (int)(blendingRate *(float)ta);
r = (int)(blendingRate *(float)tr);
g = (int)(blendingRate *(float)tg);
b = (int)(blendingRate *(float)tb);

outPixelsData[index] = ((a << 24) & 0xFF000000)
| ((r << 16) & 0x00FF0000)
| ((g << 8) & 0x0000FF00)
| ((b) & 0x000000FF);
index++;
}
}

}

本例中，为了简化计算假设alpah blending系数为0.5加载/读取图像文件的代码如下：[java] view plaincopyif (srcImageOne == null) {
File file_001 = new File("D:\\resource\\350_001.png");
srcImageOne = ImageIO.read(file_001);
}
if (srcImageTwo == null) {
File file_002 = new File("D:\\resource\\350_002.png");
srcImageTwo = ImageIO.read(file_002);
}