Java tutorial
//package com.java2s; import android.graphics.Bitmap; import java.io.ByteArrayOutputStream; public class Main { public static byte[] bitmap2Bytes(Bitmap bitmap) { ByteArrayOutputStream baos; try { baos = new ByteArrayOutputStream(); bitmap.compress(Bitmap.CompressFormat.PNG, 100, baos); byte[] b = baos.toByteArray(); baos.flush(); baos.close(); return b; } catch (Exception e) { e.printStackTrace(); } return null; } }