Java tutorial
//package com.java2s; import android.graphics.Bitmap; import java.io.ByteArrayOutputStream; import java.io.IOException; public class Main { public static byte[] bitmapToByteArray(Bitmap bitmap) { ByteArrayOutputStream stream = new ByteArrayOutputStream(); bitmap.compress(Bitmap.CompressFormat.PNG, 100, stream); byte[] array = stream.toByteArray(); try { stream.close(); } catch (IOException e) { e.printStackTrace(); } return array; } }