使用Java 实现 2张图片的SSIM算法
时间: 2024-03-27 22:35:24 浏览: 19
SSIM(结构相似性)是评估两张图片相似度的一种指标。Java实现2张图片的SSIM算法,需要用到以下步骤:
1. 将两张图片读入内存,可以使用BufferedImage类。
2. 将图片转换为灰度图像,可以使用ColorConvertOp类。
3. 将灰度图像按照一定的窗口大小划分为多个子窗口。
4. 计算每个子窗口的像素值均值、标准差和协方差。
5. 根据子窗口的像素值均值、标准差和协方差计算SSIM指数。
下面是Java代码实现:
```java
import java.awt.image.BufferedImage;
import java.awt.image.ColorConvertOp;
public class SSIM {
public static double getSSIM(BufferedImage img1, BufferedImage img2) {
int width = img1.getWidth();
int height = img1.getHeight();
// Convert images to grayscale
ColorConvertOp op = new ColorConvertOp(null);
BufferedImage grayImg1 = op.filter(img1, null);
BufferedImage grayImg2 = op.filter(img2, null);
// Set window size
int windowSize = 8;
// Set constants
double K1 = 0.01;
double K2 = 0.03;
double L = 255;
double C1 = Math.pow(K1 * L, 2);
double C2 = Math.pow(K2 * L, 2);
double ssim = 0.0;
// Loop through each window
for (int i = 0; i < height; i += windowSize) {
for (int j = 0; j < width; j += windowSize) {
double sum1 = 0.0;
double sum2 = 0.0;
double sum3 = 0.0;
// Loop through each pixel in window
for (int k = i; k < i + windowSize && k < height; k++) {
for (int l = j; l < j + windowSize && l < width; l++) {
double pixel1 = grayImg1.getRGB(l, k) & 0xff;
double pixel2 = grayImg2.getRGB(l, k) & 0xff;
sum1 += pixel1;
sum2 += pixel2;
sum3 += pixel1 * pixel2;
}
}
// Calculate mean and covariance
double n = windowSize * windowSize;
double mean1 = sum1 / n;
double mean2 = sum2 / n;
double cov = (sum3 / n) - (mean1 * mean2);
// Calculate SSIM for this window
double numerator = (2 * mean1 * mean2 + C1) * (2 * cov + C2);
double denominator = (Math.pow(mean1, 2) + Math.pow(mean2, 2) + C1) * (Math.pow(Math.sqrt(Math.pow(cov, 2) + C2), 2));
ssim += numerator / denominator;
}
}
// Average SSIM for all windows
ssim /= (height / windowSize) * (width / windowSize);
return ssim;
}
}
```
调用方法:
```java
BufferedImage img1 = ImageIO.read(new File("img1.jpg"));
BufferedImage img2 = ImageIO.read(new File("img2.jpg"));
double ssim = SSIM.getSSIM(img1, img2);
System.out.println("SSIM: " + ssim);
```