Java tutorial
//package com.java2s; import android.graphics.Bitmap; import java.nio.ByteBuffer; public class Main { public static byte[] bitmapToBytes(Bitmap b) { //calculate how many bytes our image consists of. int bytes = b.getByteCount(); //or we can calculate bytes this way. Use a different value than 4 if you don't use 32bit images. //int bytes = b.getWidth()*b.getHeight()*4; ByteBuffer buffer = ByteBuffer.allocate(bytes); //Create a new buffer b.copyPixelsToBuffer(buffer); //Move the byte data to the buffer byte[] array = buffer.array(); return array; } }