Loading MemoryStream C #

How do I load a document over 4069 kb.

Example: I have a 14,000 kb document to load into MemoryStream that does not load because it is giving a memory exception! How can I load this file?

Code snippet:

public ElementImage(string imageBase64, Size size, Point position, bool stretch)
    : base()
{
    this.imgBase64 = imageBase64;
    this.Size = size;
    this.Position = position;
    this.Stretch = stretch;

    byte[] imageData = Convert.FromBase64String(imageBase64);
    using (MemoryStream ms = new MemoryStream(imageData))
    {
        if (stretch)
            this.img = Image.FromStream(ms);
        else
        {
            Bitmap bmpImage = new Bitmap(Image.FromStream(ms));
            Bitmap bmpCrop = bmpImage.Clone(new Rectangle(this.Position.X, this.Position.Y, (int)this.Size.Width, (int)this.Size.Height), bmpImage.PixelFormat);
            this.img = (Image)(bmpCrop);
        }
    }    
}