Read image resource as byte array

ImageReader.cs

byte[] OpenImage()
{
    byte[] imageData = null;
    var assembly = GetType().GetTypeInfo().Assembly;
    string filePath = "AssemblyName" + ".FolderName.FileName.extension";

    using (Stream s = assembly.GetManifestResourceStream(filePath))
    {
        long length = s.Length;
        imageData = new byte[length];
        s.Read(imageData, 0, (int)length);
    }
}