Java tutorial
//package com.java2s; import java.io.ByteArrayOutputStream; import android.graphics.Bitmap; public class Main { public static byte[] bitmapToBytes(Bitmap bm) { byte[] bytes = null; if (bm != null) { ByteArrayOutputStream baos = new ByteArrayOutputStream(); bm.compress(Bitmap.CompressFormat.PNG, 100, baos); bytes = baos.toByteArray(); } return bytes; } }