/**
* 图片转灰度
*
* @param bmSrc
* @return
*/
public static Bitmap bitmap2Gray(Bitmap bmSrc)
{
int width, height;
height = bmSrc.getHeight();
width = bmSrc.getWidth();
Bitmap bmpGray = null;
bmpGray = Bitmap.createBitmap(width, height, Bitmap.Config.RGB_565);
Canvas c = new Canvas(bmpGray);
Paint paint = new Paint();
ColorMatrix cm = new ColorMatrix();
cm.setSaturation(0);
ColorMatrixColorFilter f = new ColorMatrixColorFilter(cm);
paint.setColorFilter(f);
c.drawBitmap(bmSrc, 0, 0, paint);

return bmpGray;
}

效果图：