Java tutorial
//package com.java2s; //License from project: Apache License import android.graphics.Bitmap; import android.graphics.Canvas; import android.graphics.ColorMatrix; import android.graphics.ColorMatrixColorFilter; import android.graphics.Paint; public class Main { public static final Bitmap grey(Bitmap bitmap) { int width = bitmap.getWidth(); int height = bitmap.getHeight(); Bitmap faceIconGreyBitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888); Canvas canvas = new Canvas(faceIconGreyBitmap); Paint paint = new Paint(); ColorMatrix colorMatrix = new ColorMatrix(); colorMatrix.setSaturation(0); ColorMatrixColorFilter colorMatrixFilter = new ColorMatrixColorFilter(colorMatrix); paint.setColorFilter(colorMatrixFilter); canvas.drawBitmap(bitmap, 0, 0, paint); return faceIconGreyBitmap; } }