-4
以下是用於圖像處理的代碼。我在通過檢查手指放在相機上時的紅色強度來計算每分鐘心跳次數的應用程序中找到此代碼。我注意到在幾個需要圖像處理的地方使用decodeYUV方法。我螞蟻在這裏知道兩件事:有人可以解釋這個圖像處理算法嗎?
- 什麼是YUV,爲什麼它被使用?
- 該算法如何工作來找出紅色的強度?
Ë
private static int decodeYUV420SPtoRedSum(byte[] yuv420sp, int width, int height) {
if (yuv420sp == null) return 0;
final int frameSize = width * height;
int sum = 0;
for (int j = 0, yp = 0; j < height; j++) {
int uvp = frameSize + (j >> 1) * width, u = 0, v = 0;
for (int i = 0; i < width; i++, yp++) {
int y = (0xff & yuv420sp[yp]) - 16;
if (y < 0) y = 0;
if ((i & 1) == 0) {
v = (0xff & yuv420sp[uvp++]) - 128;
u = (0xff & yuv420sp[uvp++]) - 128;
}
int y1192 = 1192 * y;
int r = (y1192 + 1634 * v);
int g = (y1192 - 833 * v - 400 * u);
int b = (y1192 + 2066 * u);
if (r < 0) r = 0;
else if (r > 262143) r = 262143;
if (g < 0) g = 0;
else if (g > 262143) g = 262143;
if (b < 0) b = 0;
else if (b > 262143) b = 262143;
int pixel = 0xff000000 | ((r << 6) & 0xff0000) | ((g >> 2) & 0xff00) | ((b >> 10) & 0xff);
int red = (pixel >> 16) & 0xff;
sum += red;
}
}
return sum;
}`
https://www.google.com/search?q=YUV+color和https://en.wikipedia.org/wiki/YUV –