/// <summary>
/// Extracts the content from the image
/// </summary>
/// <param name="img">the image from which to extract</param>
/// <param name="planes">the planes to embed in</param>
/// <param name="bitDepth">the bit depth of the embedding</param>
/// <returns>the embedded content, null if a problem occurs</returns>
public static EmbeddingContent Extract(Bitmap img, EmbeddingPlane planes, int bitDepth)
{
// short circuit
if ((img == null) || (bitDepth < 1) || (bitDepth > 8))
{
return(null);
}
// var declatation
EmbeddingContent retVal = null;
try
{
// get the header to determine what to extract
EmbeddingHeader eh = new EmbeddingHeader(img, planes, bitDepth);
// read the bytes
int totalBytesToExtract = eh.ToString().Length + eh.SizeOfContent;
retVal = new EmbeddingContent(SteganographyMethods.ExtractBytes(img, planes, bitDepth, totalBytesToExtract));
}
catch
{
retVal = null;
}
return(retVal);
}
/// <summary>
/// Internal constructor that builds the object from bytes
/// </summary>
/// <param name="img">the image in which to embed</param>
/// <param name="planes">the planes to embed in</param>
/// <param name="bitDepth">the bit depth of the embedding</param>
/// <returns>the embedding header</returns>
internal EmbeddingHeader(Bitmap img, EmbeddingPlane planes, int bitDepth)
{
try
{
// get header
byte[] headerBytes = SteganographyMethods.ExtractBytes(img, planes, bitDepth, MAX_HEADER);
String header = System.Text.Encoding.ASCII.GetString(headerBytes).Trim();
String[] split = header.Split(new char[1] {
HEADER_SPLIT_CHAR
});
// set attributes
this.TypeOfContent = (ContentType)Enum.Parse(typeof(ContentType), split[0].Trim());
this.SizeOfContent = Convert.ToInt32(split[1].Trim());
this.Filename = split[2].Trim();
}
catch (Exception e)
{
throw new SteganographyException(e.ToString());
}
}
