/// <summary>
/// Prepends a proper TIFF image header to the the CCITTFaxDecode image data.
/// </summary>
/// <param name="imageData">The metadata about the image.</param>
/// <param name="image">The original compressed image.</param>
/// <returns>A properly formatted TIFF header and the compressed image data.</returns>
private static byte[] GetTiffImageBufferFromCCITTFaxDecode(PdfDictionaryImageMetaData imageData, byte[] image)
{
const short TIFF_BIGENDIAN = 0x4d4d;
const short TIFF_LITTLEENDIAN = 0x4949;
const int ifd_length = 10;
const int header_length = 10 + (ifd_length * 12 + 4);
using (MemoryStream buffer = new MemoryStream(header_length + image.Length)) {
// TIFF Header
buffer.Write(BitConverter.GetBytes(BitConverter.IsLittleEndian ? TIFF_LITTLEENDIAN : TIFF_BIGENDIAN), 0, 2); // tiff_magic (big/little endianness)
buffer.Write(BitConverter.GetBytes((uint)42), 0, 2); // tiff_version
buffer.Write(BitConverter.GetBytes((uint)8), 0, 4); // first_ifd (Image file directory) / offset
buffer.Write(BitConverter.GetBytes((uint)ifd_length), 0, 2); // ifd_length, number of tags (ifd entries)
// Dictionary should be in order based on the TiffTag value
WriteTiffTag(buffer, TiffTag.SUBFILETYPE, TiffType.LONG, 1, 0);
WriteTiffTag(buffer, TiffTag.IMAGEWIDTH, TiffType.LONG, 1, (uint)imageData.Width);
WriteTiffTag(buffer, TiffTag.IMAGELENGTH, TiffType.LONG, 1, (uint)imageData.Height);
WriteTiffTag(buffer, TiffTag.BITSPERSAMPLE, TiffType.SHORT, 1, (uint)imageData.BitsPerPixel);
WriteTiffTag(buffer, TiffTag.COMPRESSION, TiffType.SHORT, 1, (uint)imageData.Compression);
WriteTiffTag(buffer, TiffTag.PHOTOMETRIC, TiffType.SHORT, 1, 0); // WhiteIsZero
WriteTiffTag(buffer, TiffTag.STRIPOFFSETS, TiffType.LONG, 1, header_length);
WriteTiffTag(buffer, TiffTag.SAMPLESPERPIXEL, TiffType.SHORT, 1, 1);
WriteTiffTag(buffer, TiffTag.ROWSPERSTRIP, TiffType.LONG, 1, (uint)imageData.Height);
WriteTiffTag(buffer, TiffTag.STRIPBYTECOUNTS, TiffType.LONG, 1, (uint)image.Length);
// Next IFD Offset
buffer.Write(BitConverter.GetBytes((uint)0), 0, 4);
buffer.Write(image, 0, image.Length);
return(buffer.GetBuffer());
}
}
/// <summary>
/// Retrieves the specifed dictionary object as an object encoded with FlateDecode filter.
/// </summary>
/// <remarks>
/// FlateDecode a commonly used filter based on the zlib/deflate algorithm (a.k.a. gzip, but not zip)
/// defined in RFC 1950 and RFC 1951; introduced in PDF 1.2; it can use one of two groups of predictor
/// functions for more compact zlib/deflate compression: Predictor 2 from the TIFF 6.0 specification
/// and predictors (filters) from the PNG specification (RFC 2083)
/// </remarks>
/// <param name="dictionary">The dictionary to extract the object from.</param>
/// <returns>The image retrieve from the dictionary. If not found or an invalid image, then null is returned.</returns>
private static Image ImageFromFlateDecode(PdfDictionary dictionary)
{
PdfDictionaryImageMetaData imageData = new PdfDictionaryImageMetaData(dictionary);
// FlateDecode can be either indexed or a traditional ColorSpace
bool isIndexed = imageData.ColorSpace.IsIndexed;
PixelFormat format = GetPixelFormat(imageData.ColorSpace, imageData.BitsPerPixel, isIndexed);
Bitmap bitmap = new Bitmap(imageData.Width, imageData.Height, format);
// If indexed, retrieve and assign the color palette for the item.
if ((isIndexed) && (imageData.ColorSpace.IsRGB)) bitmap.Palette = ((PdfIndexedRGBColorSpace) imageData.ColorSpace).ToColorPalette();
else if (imageData.ColorSpace is PdfGrayColorSpace) bitmap.Palette = ((PdfGrayColorSpace)imageData.ColorSpace).ToColorPalette(imageData.BitsPerPixel);
// If not an indexed color, the .NET image component expects pixels to be in BGR order. However, our PDF stream is in RGB order.
byte[] stream = (format == PixelFormat.Format24bppRgb) ? ConvertRGBStreamToBGR(dictionary.Stream.UnfilteredValue) : dictionary.Stream.UnfilteredValue;
BitmapData bitmapData = bitmap.LockBits(new Rectangle(0, 0, imageData.Width, imageData.Height), ImageLockMode.WriteOnly, format);
// We can't just copy the bytes directly; the BitmapData .NET class has a stride (padding) associated with it.
int bitsPerPixel = ((((int)format >> 8) & 0xFF));
int length = (int)Math.Ceiling(bitmapData.Width * bitsPerPixel / 8.0);
for (int y = 0, height = bitmapData.Height; y < height; y++) {
int offset = y * length;
Marshal.Copy(stream, offset, bitmapData.Scan0 + (y * bitmapData.Stride), length);
}
bitmap.UnlockBits(bitmapData);
return (bitmap);
}
/// <summary>
/// Retrieves the specifed dictionary object as an object encoded with CCITTFaxDecode filter (TIFF).
/// </summary>
/// <param name="dictionary">The dictionary to extract the object from.</param>
/// <returns>The image retrieve from the dictionary. If not found or an invalid image, then null is returned.</returns>
private static Image ImageFromCCITTFaxDecode(PdfDictionary dictionary)
{
Image image = null;
PdfDictionaryImageMetaData imageData = new PdfDictionaryImageMetaData(dictionary);
PixelFormat format = GetPixelFormat(imageData.ColorSpace, imageData.BitsPerPixel, true);
Bitmap bitmap = new Bitmap(imageData.Width, imageData.Height, format);
// Determine if BLACK=1, create proper indexed color palette.
CCITTFaxDecodeParameters ccittFaxDecodeParameters = new CCITTFaxDecodeParameters(dictionary.Elements["/DecodeParms"].Get() as PdfDictionary);
if (ccittFaxDecodeParameters.BlackIs1) bitmap.Palette = PdfIndexedColorSpace.CreateColorPalette(Color.Black, Color.White);
else bitmap.Palette = PdfIndexedColorSpace.CreateColorPalette(Color.White, Color.Black);
using (MemoryStream stream = new MemoryStream(GetTiffImageBufferFromCCITTFaxDecode(imageData, dictionary.Stream.Value))) {
using (Tiff tiff = Tiff.ClientOpen("<INLINE>", "r", stream, new TiffStream())) {
if (tiff == null) return (null);
int stride = tiff.ScanlineSize();
byte[] buffer = new byte[stride];
for (int i = 0; i < imageData.Height; i++) {
tiff.ReadScanline(buffer, i);
Rectangle imgRect = new Rectangle(0, i, imageData.Width, 1);
BitmapData imgData = bitmap.LockBits(imgRect, ImageLockMode.WriteOnly, PixelFormat.Format1bppIndexed);
Marshal.Copy(buffer, 0, imgData.Scan0, buffer.Length);
bitmap.UnlockBits(imgData);
}
}
}
return (bitmap);
}
/// <summary>
/// Retrieves the specifed dictionary object as an object encoded with FlateDecode filter.
/// </summary>
/// <remarks>
/// FlateDecode a commonly used filter based on the zlib/deflate algorithm (a.k.a. gzip, but not zip)
/// defined in RFC 1950 and RFC 1951; introduced in PDF 1.2; it can use one of two groups of predictor
/// functions for more compact zlib/deflate compression: Predictor 2 from the TIFF 6.0 specification
/// and predictors (filters) from the PNG specification (RFC 2083)
/// </remarks>
/// <param name="dictionary">The dictionary to extract the object from.</param>
/// <returns>The image retrieve from the dictionary. If not found or an invalid image, then null is returned.</returns>
private static Image ImageFromFlateDecode(PdfDictionary dictionary)
{
PdfDictionaryImageMetaData imageData = new PdfDictionaryImageMetaData(dictionary);
// FlateDecode can be either indexed or a traditional ColorSpace
bool isIndexed = imageData.ColorSpace.IsIndexed;
PixelFormat format = GetPixelFormat(imageData.ColorSpace, imageData.BitsPerPixel, isIndexed);
Bitmap bitmap = new Bitmap(imageData.Width, imageData.Height, format);
// If indexed, retrieve and assign the color palette for the item.
if ((isIndexed) && (imageData.ColorSpace.IsRGB)) bitmap.Palette = ((PdfIndexedRGBColorSpace) imageData.ColorSpace).ToColorPalette();
else if (imageData.ColorSpace is PdfGrayColorSpace) bitmap.Palette = ((PdfGrayColorSpace)imageData.ColorSpace).ToColorPalette(imageData.BitsPerPixel);
// If not an indexed color, the .NET image component expects pixels to be in BGR order. However, our PDF stream is in RGB order.
byte[] stream = (format == PixelFormat.Format24bppRgb) ? ConvertRGBStreamToBGR(dictionary.Stream.UnfilteredValue) : dictionary.Stream.UnfilteredValue;
BitmapData bitmapData = bitmap.LockBits(new Rectangle(0, 0, imageData.Width, imageData.Height), ImageLockMode.WriteOnly, format);
// We can't just copy the bytes directly; the BitmapData .NET class has a stride (padding) associated with it.
int bitsPerPixel = ((((int)format >> 8) & 0xFF));
int length = (int)Math.Ceiling(bitmapData.Width * bitsPerPixel / 8.0);
for (int y = 0, height = bitmapData.Height; y < height; y++) {
int offset = y * length;
Marshal.Copy(stream, offset, bitmapData.Scan0 + (y * bitmapData.Stride), length);
}
bitmap.UnlockBits(bitmapData);
return (bitmap);
}
/// <summary>
/// Retrieves the specifed dictionary object as an object encoded with CCITTFaxDecode filter (TIFF).
/// </summary>
/// <param name="dictionary">The dictionary to extract the object from.</param>
/// <returns>The image retrieve from the dictionary. If not found or an invalid image, then null is returned.</returns>
private static Image ImageFromCCITTFaxDecode(PdfDictionary dictionary)
{
Image image = null;
PdfDictionaryImageMetaData imageData = new PdfDictionaryImageMetaData(dictionary);
PixelFormat format = GetPixelFormat(imageData.ColorSpace, imageData.BitsPerPixel, true);
Bitmap bitmap = new Bitmap(imageData.Width, imageData.Height, format);
// Determine if BLACK=1, create proper indexed color palette.
CCITTFaxDecodeParameters ccittFaxDecodeParameters = new CCITTFaxDecodeParameters(dictionary.Elements["/DecodeParms"].Get() as PdfDictionary);
if (ccittFaxDecodeParameters.BlackIs1) bitmap.Palette = PdfIndexedColorSpace.CreateColorPalette(Color.Black, Color.White);
else bitmap.Palette = PdfIndexedColorSpace.CreateColorPalette(Color.White, Color.Black);
using (MemoryStream stream = new MemoryStream(GetTiffImageBufferFromCCITTFaxDecode(imageData, dictionary.Stream.Value))) {
using (Tiff tiff = Tiff.ClientOpen("<INLINE>", "r", stream, new TiffStream())) {
if (tiff == null) return (null);
int stride = tiff.ScanlineSize();
byte[] buffer = new byte[stride];
for (int i = 0; i < imageData.Height; i++) {
tiff.ReadScanline(buffer, i);
Rectangle imgRect = new Rectangle(0, i, imageData.Width, 1);
BitmapData imgData = bitmap.LockBits(imgRect, ImageLockMode.WriteOnly, PixelFormat.Format1bppIndexed);
Marshal.Copy(buffer, 0, imgData.Scan0, buffer.Length);
bitmap.UnlockBits(imgData);
}
}
}
return (bitmap);
}
/// <summary>
/// Prepends a proper TIFF image header to the the CCITTFaxDecode image data.
/// </summary>
/// <param name="imageData">The metadata about the image.</param>
/// <param name="image">The original compressed image.</param>
/// <returns>A properly formatted TIFF header and the compressed image data.</returns>
private static byte[] GetTiffImageBufferFromCCITTFaxDecode(PdfDictionaryImageMetaData imageData, byte[] image)
{
const short TIFF_BIGENDIAN = 0x4d4d;
const short TIFF_LITTLEENDIAN = 0x4949;
const int ifd_length = 10;
const int header_length = 10 + (ifd_length * 12 + 4);
using (MemoryStream buffer = new MemoryStream(header_length + image.Length)) {
// TIFF Header
buffer.Write(BitConverter.GetBytes(BitConverter.IsLittleEndian ? TIFF_LITTLEENDIAN : TIFF_BIGENDIAN), 0, 2); // tiff_magic (big/little endianness)
buffer.Write(BitConverter.GetBytes((uint)42), 0, 2); // tiff_version
buffer.Write(BitConverter.GetBytes((uint)8), 0, 4); // first_ifd (Image file directory) / offset
buffer.Write(BitConverter.GetBytes((uint)ifd_length), 0, 2); // ifd_length, number of tags (ifd entries)
// Dictionary should be in order based on the TiffTag value
WriteTiffTag(buffer, TiffTag.SUBFILETYPE, TiffType.LONG, 1, 0);
WriteTiffTag(buffer, TiffTag.IMAGEWIDTH, TiffType.LONG, 1, (uint)imageData.Width);
WriteTiffTag(buffer, TiffTag.IMAGELENGTH, TiffType.LONG, 1, (uint)imageData.Height);
WriteTiffTag(buffer, TiffTag.BITSPERSAMPLE, TiffType.SHORT, 1, (uint)imageData.BitsPerPixel);
WriteTiffTag(buffer, TiffTag.COMPRESSION, TiffType.SHORT, 1, (uint) Compression.CCITTFAX4); // CCITT Group 4 fax encoding.
WriteTiffTag(buffer, TiffTag.PHOTOMETRIC, TiffType.SHORT, 1, 0); // WhiteIsZero
WriteTiffTag(buffer, TiffTag.STRIPOFFSETS, TiffType.LONG, 1, header_length);
WriteTiffTag(buffer, TiffTag.SAMPLESPERPIXEL, TiffType.SHORT, 1, 1);
WriteTiffTag(buffer, TiffTag.ROWSPERSTRIP, TiffType.LONG, 1, (uint)imageData.Height);
WriteTiffTag(buffer, TiffTag.STRIPBYTECOUNTS, TiffType.LONG, 1, (uint)image.Length);
// Next IFD Offset
buffer.Write(BitConverter.GetBytes((uint)0), 0, 4);
buffer.Write(image, 0, image.Length);
return(buffer.GetBuffer());
}
}
/// <summary>
/// Retrieves the specifed dictionary object as an object encoded with CCITTFaxDecode filter (TIFF).
/// </summary>
/// <param name="dictionary">The dictionary to extract the object from.</param>
/// <returns>The image retrieve from the dictionary. If not found or an invalid image, then null is returned.</returns>
private static Image ImageFromCCITTFaxDecode(PdfDictionary dictionary)
{
PdfDictionaryImageMetaData imageData = new PdfDictionaryImageMetaData(dictionary);
PixelFormat format = GetPixelFormat(imageData.ColorSpace, imageData.BitsPerPixel, true);
Bitmap bitmap = new Bitmap(imageData.Width, imageData.Height, format);
// Determine if BLACK=1, create proper indexed color palette.
PdfDictionary decodeParams;
var decodeParamsObject = dictionary.Elements["/DecodeParms"].Get();
if (decodeParamsObject is PdfArray)
{
decodeParams = (decodeParamsObject as PdfArray).First() as PdfDictionary;
}
else if (decodeParamsObject is PdfDictionary)
{
decodeParams = decodeParamsObject as PdfDictionary;
}
else
{
throw new NotSupportedException("Unknown format of CCITTFaxDecode params.");
}
CCITTFaxDecodeParameters ccittFaxDecodeParameters = new CCITTFaxDecodeParameters(decodeParams);
if (ccittFaxDecodeParameters.BlackIs1)
{
bitmap.Palette = PdfIndexedColorSpace.CreateColorPalette(Color.Black, Color.White);
}
else
{
bitmap.Palette = PdfIndexedColorSpace.CreateColorPalette(Color.White, Color.Black);
}
if (ccittFaxDecodeParameters.K == 0 || ccittFaxDecodeParameters.K > 0)
{
imageData.Compression = Compression.CCITTFAX3;
}
else if (ccittFaxDecodeParameters.K < 0)
{
imageData.Compression = Compression.CCITTFAX4;
}
using (MemoryStream stream = new MemoryStream(GetTiffImageBufferFromCCITTFaxDecode(imageData, dictionary.Stream.Value))) {
using (Tiff tiff = Tiff.ClientOpen("<INLINE>", "r", stream, new TiffStream())) {
if (tiff == null)
{
return(null);
}
int stride = tiff.ScanlineSize();
byte[] buffer = new byte[stride];
for (int i = 0; i < imageData.Height; i++)
{
tiff.ReadScanline(buffer, i);
Rectangle imgRect = new Rectangle(0, i, imageData.Width, 1);
BitmapData imgData = bitmap.LockBits(imgRect, ImageLockMode.WriteOnly, PixelFormat.Format1bppIndexed);
Marshal.Copy(buffer, 0, imgData.Scan0, buffer.Length);
bitmap.UnlockBits(imgData);
}
}
}
return(bitmap);
}
