[C#]取用.picasa.ini內存的現有資訊來做臉部偵測

November 6, 2013

rect64(3f845bcb59418507)

break this number into 4 16-bit numbers by using substrings:

‘3f845bcb59418507’.substring(0,4) //“3f84”

‘3f845bcb59418507’.substring(4,8) //“5bcb”

‘3f845bcb59418507’.substring(8,12) // “5941”

‘3f845bcb59418507’.substring(12,16) // “8507”

convert each obtained substring to an integer and divide it

by the highest 16-bit number (2^16 = 65536), which should give 0 < results < 1.

these are the relative coordinates of the crop rectangle (left,top,right,bottom):

parseInt(“3f84”,16)/65536 //0.24810791015625 - left

parseInt(“5bcb”,16)/65536 //0.3585662841796875 - top

parseInt(“5941”,16)/65536 //0.3486480712890625 - right

parseInt(“8507”,16)/65536 //0.5196380615234375 - bottom

for absolute coordinates, multiply the left/right coordinates with

the image width and the top/bottom coordinates with the image height

        UInt16 l16 = BitConverter.ToUInt16(bytes, 6);
        UInt16 t16 = BitConverter.ToUInt16(bytes, 4);
        UInt16 r16 = BitConverter.ToUInt16(bytes, 2);
        UInt16 b16 = BitConverter.ToUInt16(bytes, 0);

        float left = l16 / 65535.0F;
        float top = t16 / 65535.0F;
        float right = r16 / 65535.0F;
        float bottom = b16 / 65535.0F;

        return new RectangleF(left, top, right - left, bottom - top);
    }</pre></div>

namespace WindowsFormsApplication27 { public class PicasaMetaDataHelper { #region DllImport [DllImport(“kernel32”)] private static extern int GetPrivateProfileString(string section, string key, string def, StringBuilder retVal, int size, string filePath); #endregion

	#region Const
	const string PICASA_INI_FILENAME = ".picasa.ini";
	const string FACE_HASH_CODE_PATTERN = @"\((\w+)\)";
	#endregion

	#region Private Static Method
	/// &lt;summary&gt;
	/// Gets the rectangle from64 hash.
	/// &lt;/summary&gt;
	/// &lt;param name="hash64"&gt;The hash64.&lt;/param&gt;
	/// &lt;param name="size"&gt;The size.&lt;/param&gt;
	/// &lt;returns&gt;&lt;/returns&gt;
	private static RectangleF GetRectangleFrom64Hash(string hash64, Size size)
	{
		return GetRectangleFrom64Hash(hash64, size.Width, size.Height);
	}

	/// &lt;summary&gt;
	/// Gets the rectangle from64 hash.
	/// &lt;/summary&gt;
	/// &lt;param name="hash64"&gt;The hash64.&lt;/param&gt;
	/// &lt;param name="width"&gt;The width.&lt;/param&gt;
	/// &lt;param name="height"&gt;The height.&lt;/param&gt;
	/// &lt;returns&gt;&lt;/returns&gt;
	private static RectangleF GetRectangleFrom64Hash(string hash64, int width, int height)
	{
		UInt64 hash = UInt64.Parse(hash64, System.Globalization.NumberStyles.HexNumber);
		byte[] bytes = BitConverter.GetBytes(hash);

		UInt16 l16 = BitConverter.ToUInt16(bytes, 6);
		UInt16 t16 = BitConverter.ToUInt16(bytes, 4);
		UInt16 r16 = BitConverter.ToUInt16(bytes, 2);
		UInt16 b16 = BitConverter.ToUInt16(bytes, 0);

		float left = l16 / 65535.0F;
		float top = t16 / 65535.0F;
		float right = r16 / 65535.0F;
		float bottom = b16 / 65535.0F;

		return new RectangleF(left * width, top * height, (right - left) * width, (bottom - top) * height);
	} 
	#endregion


	#region Public Static Method
	/// &lt;summary&gt;
	/// Gets the face areas.
	/// &lt;/summary&gt;
	/// &lt;param name="photoFile"&gt;The photo file.&lt;/param&gt;
	/// &lt;returns&gt;&lt;/returns&gt;
	public static IEnumerable&lt;RectangleF&gt; GetFaceAreas(string photoFile)
	{
		var photo = Bitmap.FromFile(photoFile);
		return GetFaceAreas(photoFile, photo);
	}

	/// &lt;summary&gt;
	/// Gets the face areas.
	/// &lt;/summary&gt;
	/// &lt;param name="photoFile"&gt;The photo file.&lt;/param&gt;
	/// &lt;param name="photo"&gt;The photo.&lt;/param&gt;
	/// &lt;returns&gt;&lt;/returns&gt;
	public static IEnumerable&lt;RectangleF&gt; GetFaceAreas(string photoFile, Image photo)
	{
		var folder = Path.GetDirectoryName(photoFile);
		var iniFile = Path.Combine(folder, PICASA_INI_FILENAME);

		if (!File.Exists(iniFile))
			yield break;

		var fileName = Path.GetFileName(photoFile);
		var faceDataBuffer = new StringBuilder(512);
		GetPrivateProfileString(fileName, "faces", string.Empty, faceDataBuffer, 512, iniFile);

		var faceData = faceDataBuffer.ToString();

		if (faceData.Length == 0)
			yield break;

		var ms = Regex.Matches(faceData, FACE_HASH_CODE_PATTERN);

		foreach (Match m in ms)
		{
			var faceHashCode = m.Groups[1].Value;
			yield return GetRectangleFrom64Hash(faceHashCode, photo.Size);
		}
	}
	#endregion
}

}

			using (var g = Graphics.FromImage(image))
			{
				g.DrawRectangles(new Pen(Brushes.Red, 5), faceAreas.ToArray());
			}
			pbxPhoto.Image = image;
		}
		...</pre></div>

CSharp