Java tutorial
//package com.java2s; import android.graphics.Bitmap; import android.util.Base64; import java.io.ByteArrayOutputStream; public class Main { public static String bitmap2PNGBase64(Bitmap bitmap) { return Base64.encodeToString(bitmap2PNGByteArray(bitmap), Base64.DEFAULT); } public static byte[] bitmap2PNGByteArray(Bitmap bitmap) { ByteArrayOutputStream stream = new ByteArrayOutputStream(); bitmap.compress(Bitmap.CompressFormat.PNG, 100, stream); return stream.toByteArray(); } }