Java tutorial
//package com.java2s; import java.io.ByteArrayOutputStream; import android.graphics.Bitmap; import android.graphics.Bitmap.CompressFormat; public class Main { public static byte[] Bitmap2Bytes(Bitmap bm) { ByteArrayOutputStream baos = new ByteArrayOutputStream(); bm.compress(CompressFormat.PNG, 100, baos); bm.recycle(); return baos.toByteArray(); } }