android把彩色图像变成灰度图（黑白）

 1 ImageView iv = new ImageView(this);

 2 setContentView(iv);

 3 Bitmap originImg = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);

 4 Bitmap grayImg = Bitmap.createBitmap(originImg.getWidth(), originImg.getHeight(), Bitmap.Config.ARGB_8888);

 5 Canvas canvas = new Canvas(grayImg);

 6 Paint paint = new Paint();

 7 ColorMatrix colorMatrix = new ColorMatrix();

 8 colorMatrix.setSaturation(0);

 9 ColorMatrixColorFilter colorMatrixFilter = new ColorMatrixColorFilter(colorMatrix);

10 paint.setColorFilter(colorMatrixFilter);

11 canvas.drawBitmap(originImg, 0, 0, paint);

12 iv.setImageBitmap(grayImg);

这里起关键作用的是colorMatrix.setSaturation(0);

0会把图像变成灰度图。只有黑白。