Image Validation in C#

public enum ImageFormat
{
    bmp,
    jpeg,
    gif,
    tiff,
    png,
    unknown
}

public static ImageFormat GetImageFormat(byte[] bytes)
    {
        // see http://www.mikekunz.com/image_file_header.html
        var bmp = Encoding.ASCII.GetBytes("BM"); // BMP
        var gif = Encoding.ASCII.GetBytes("GIF"); // GIF
        var png = new byte[]
        {
            137,
            80,
            78,
            71
        }; // PNG
        var tiff = new byte[]
        {
            73,
            73,
            42
        }; // TIFF
        var tiff2 = new byte[]
        {
            77,
            77,
            42
        }; // TIFF
        var jpeg = new byte[]
        {
            255,
            216,
            255,
            224
        }; // jpeg
        var jpeg2 = new byte[]
        {
            255,
            216,
            255,
            225
        }; // jpeg canon

        if (bmp.SequenceEqual(bytes.Take(bmp.Length)))
            return ImageFormat.bmp;

        if (gif.SequenceEqual(bytes.Take(gif.Length)))
            return ImageFormat.gif;

        if (png.SequenceEqual(bytes.Take(png.Length)))
            return ImageFormat.png;

        if (tiff.SequenceEqual(bytes.Take(tiff.Length)))
            return ImageFormat.tiff;

        if (tiff2.SequenceEqual(bytes.Take(tiff2.Length)))
            return ImageFormat.tiff;