[C#] Validate image from file

This article is quoted from https://stackoverflow.com/questions/210650/validate-image-from-file-in-c-sharp/210677

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;

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

    if (jpeg2.SequenceEqual(bytes.Take(jpeg2.Length)))
        return ImageFormat.jpeg;

    return ImageFormat.unknown;
}