android 将彩色图转换为灰度图

/**

* 将彩色图转换为灰度图

* @param img 位图

*

* return 返回转换好的位图

*/

public Bitmap convertGreyImg(Bitmap img) {

int width = img.getWidth(); //获取位图的宽

int height = img.getHeight(); //获取位图的高



int []pixels = new int[width * height]; //通过位图的大小创建像素点数组



img.getPixels(pixels, 0, width, 0, 0, width, height);

int alpha = 0xFF << 24;

for(int i = 0; i < height; i++) {

for(int j = 0; j < width; j++) {

int grey = pixels[width * i + j];



int red = ((grey & 0x00FF0000 ) >> 16);

int green = ((grey & 0x0000FF00) >> 8);

int blue = (grey & 0x000000FF);



grey = (int)((float) red * 0.3 + (float)green * 0.59 + (float)blue * 0.11);

grey = alpha | (grey << 16) | (grey << 8) | grey;

pixels[width * i + j] = grey;

}

}

Bitmap result = Bitmap.createBitmap(width, height, Config.RGB_565);

result.setPixels(pixels, 0, width, 0, 0, width, height);

return result;

}