/// <summary>
/// Writes decoded pixel to buffer at a given position.
/// </summary>
/// <param name="buffer">The buffer to write to.</param>
/// <param name="offset">The position to write to.</param>
/// <returns>The number of bytes written.</returns>
public int WriteTo(Span <byte> buffer, int offset)
{
if (this.Length == 0)
{
return(0);
}
if (this.Length == 1)
{
buffer[offset] = this.value;
return(1);
}
LzwString e = this;
int endIdx = this.Length - 1;
if (endIdx >= buffer.Length)
{
TiffThrowHelper.ThrowImageFormatException("Error reading lzw compressed stream. Either pixel buffer to write to is to small or code length is invalid!");
}
for (int i = endIdx; i >= 0; i--)
{
buffer[offset + i] = e.value;
e = e.previous;
}
return(this.Length);
}
private void AddStringToTable(LzwString lzwString)
{
if (this.tableLength > this.table.Length)
{
TiffThrowHelper.ThrowImageFormatException($"TIFF LZW with more than {MaxBits} bits per code encountered (table overflow)");
}
this.table[this.tableLength++] = lzwString;
if (this.tableLength > this.maxCode)
{
this.bitsPerCode++;
if (this.bitsPerCode > MaxBits)
{
// Continue reading MaxBits (12 bit) length codes.
this.bitsPerCode = MaxBits;
}
this.bitMask = BitmaskFor(this.bitsPerCode);
this.maxCode = this.MaxCode();
}
if (lzwString.Length > this.maxString)
{
this.maxString = lzwString.Length;
}
}
/// <summary>
/// Decodes and decompresses all pixel indices from the stream.
/// </summary>
/// <param name="pixels">The pixel array to decode to.</param>
public void DecodePixels(Span <byte> pixels)
{
// Adapted from the pseudo-code example found in the TIFF 6.0 Specification, 1992.
// See Section 13: "LZW Compression"/"LZW Decoding", page 61+
int code;
int offset = 0;
while ((code = this.GetNextCode()) != EoiCode)
{
if (code == ClearCode)
{
this.Init();
code = this.GetNextCode();
if (code == EoiCode)
{
break;
}
if (this.table[code] == null)
{
TiffThrowHelper.ThrowImageFormatException($"Corrupted TIFF LZW: code {code} (table size: {this.tableLength})");
}
offset += this.table[code].WriteTo(pixels, offset);
}
else
{
if (this.table[this.oldCode] == null)
{
TiffThrowHelper.ThrowImageFormatException($"Corrupted TIFF LZW: code {this.oldCode} (table size: {this.tableLength})");
}
if (this.IsInTable(code))
{
offset += this.table[code].WriteTo(pixels, offset);
this.AddStringToTable(this.table[this.oldCode].Concatenate(this.table[code].FirstChar));
}
else
{
LzwString outString = this.table[this.oldCode].Concatenate(this.table[this.oldCode].FirstChar);
offset += outString.WriteTo(pixels, offset);
this.AddStringToTable(outString);
}
}
this.oldCode = code;
if (offset >= pixels.Length)
{
break;
}
}
}
private void LoadNewByte()
{
this.Position++;
this.ResetBitsRead();
if (this.Position >= (ulong)this.DataLength)
{
TiffThrowHelper.ThrowImageFormatException("tiff image has invalid ccitt compressed data");
}
}
/// <inheritdoc/>
protected override void Decompress(BufferedReadStream stream, int byteCount, int stripHeight, Span <byte> buffer)
{
if (this.compressedDataMemory == null)
{
this.compressedDataMemory = this.Allocator.Allocate <byte>(byteCount);
}
else if (this.compressedDataMemory.Length() < byteCount)
{
this.compressedDataMemory.Dispose();
this.compressedDataMemory = this.Allocator.Allocate <byte>(byteCount);
}
Span <byte> compressedData = this.compressedDataMemory.GetSpan();
stream.Read(compressedData, 0, byteCount);
int compressedOffset = 0;
int decompressedOffset = 0;
while (compressedOffset < byteCount)
{
byte headerByte = compressedData[compressedOffset];
if (headerByte <= 127)
{
int literalOffset = compressedOffset + 1;
int literalLength = compressedData[compressedOffset] + 1;
if ((literalOffset + literalLength) > compressedData.Length)
{
TiffThrowHelper.ThrowImageFormatException("Tiff packbits compression error: not enough data.");
}
compressedData.Slice(literalOffset, literalLength).CopyTo(buffer.Slice(decompressedOffset));
compressedOffset += literalLength + 1;
decompressedOffset += literalLength;
}
else if (headerByte == 0x80)
{
compressedOffset += 1;
}
else
{
byte repeatData = compressedData[compressedOffset + 1];
int repeatLength = 257 - headerByte;
ArrayCopyRepeat(repeatData, buffer, decompressedOffset, repeatLength);
compressedOffset += 2;
decompressedOffset += repeatLength;
}
}
}
/// <summary>
/// Decompresses image data into the supplied buffer.
/// </summary>
/// <param name="stream">The <see cref="Stream" /> to read image data from.</param>
/// <param name="stripOffset">The strip offset of stream.</param>
/// <param name="stripByteCount">The number of bytes to read from the input stream.</param>
/// <param name="stripHeight">The height of the strip.</param>
/// <param name="buffer">The output buffer for uncompressed data.</param>
public void Decompress(BufferedReadStream stream, ulong stripOffset, ulong stripByteCount, int stripHeight, Span <byte> buffer)
{
DebugGuard.MustBeLessThanOrEqualTo(stripOffset, (ulong)long.MaxValue, nameof(stripOffset));
DebugGuard.MustBeLessThanOrEqualTo(stripByteCount, (ulong)long.MaxValue, nameof(stripByteCount));
stream.Seek((long)stripOffset, SeekOrigin.Begin);
this.Decompress(stream, (int)stripByteCount, stripHeight, buffer);
if ((long)stripOffset + (long)stripByteCount < stream.Position)
{
TiffThrowHelper.ThrowImageFormatException("Out of range when reading a strip.");
}
}
/// <summary>
/// An EOL is expected before the first data.
/// </summary>
protected virtual void ReadEolBeforeFirstData()
{
if (this.isFirstScanLine)
{
this.Value = this.ReadValue(this.eolPadding ? 16 : 12);
if (!this.IsEndOfScanLine)
{
TiffThrowHelper.ThrowImageFormatException("ccitt compression parsing error: expected start of data marker not found");
}
this.Reset();
}
}
/// <summary>
/// Decompresses image data into the supplied buffer.
/// </summary>
/// <param name="stream">The <see cref="Stream" /> to read image data from.</param>
/// <param name="stripOffset">The strip offset of stream.</param>
/// <param name="stripByteCount">The number of bytes to read from the input stream.</param>
/// <param name="stripHeight">The height of the strip.</param>
/// <param name="buffer">The output buffer for uncompressed data.</param>
public void Decompress(BufferedReadStream stream, uint stripOffset, uint stripByteCount, int stripHeight, Span <byte> buffer)
{
if (stripByteCount > int.MaxValue)
{
TiffThrowHelper.ThrowImageFormatException("The StripByteCount value is too big.");
}
stream.Seek(stripOffset, SeekOrigin.Begin);
this.Decompress(stream, (int)stripByteCount, stripHeight, buffer);
if (stripOffset + stripByteCount < stream.Position)
{
TiffThrowHelper.ThrowImageFormatException("Out of range when reading a strip.");
}
}
/// <inheritdoc/>
protected override void Decompress(BufferedReadStream stream, int byteCount, int stripHeight, Span <byte> buffer)
{
using var bitReader = new ModifiedHuffmanBitReader(stream, this.FillOrder, byteCount, this.Allocator);
buffer.Clear();
uint bitsWritten = 0;
uint pixelsWritten = 0;
while (bitReader.HasMoreData)
{
bitReader.ReadNextRun();
if (bitReader.RunLength > 0)
{
if (bitReader.IsWhiteRun)
{
BitWriterUtils.WriteBits(buffer, (int)bitsWritten, bitReader.RunLength, this.whiteValue);
}
else
{
BitWriterUtils.WriteBits(buffer, (int)bitsWritten, bitReader.RunLength, this.blackValue);
}
bitsWritten += bitReader.RunLength;
pixelsWritten += bitReader.RunLength;
}
if (pixelsWritten == this.Width)
{
bitReader.StartNewRow();
pixelsWritten = 0;
// Write padding bits, if necessary.
uint pad = 8 - (bitsWritten % 8);
if (pad != 8)
{
BitWriterUtils.WriteBits(buffer, (int)bitsWritten, pad, 0);
bitsWritten += pad;
}
}
if (pixelsWritten > this.Width)
{
TiffThrowHelper.ThrowImageFormatException("ccitt compression parsing error, decoded more pixels then image width");
}
}
}
public YCbCrConverter(Rational[] referenceBlackAndWhite, Rational[] coefficients)
{
referenceBlackAndWhite ??= DefaultReferenceBlackWhite;
coefficients ??= DefaultLuma;
if (referenceBlackAndWhite.Length != 6)
{
TiffThrowHelper.ThrowImageFormatException("reference black and white array should have 6 entry's");
}
if (coefficients.Length != 3)
{
TiffThrowHelper.ThrowImageFormatException("luma coefficients array should have 6 entry's");
}
this.yExpander = new CodingRangeExpander(referenceBlackAndWhite[0], referenceBlackAndWhite[1], 255);
this.cbExpander = new CodingRangeExpander(referenceBlackAndWhite[2], referenceBlackAndWhite[3], 127);
this.crExpander = new CodingRangeExpander(referenceBlackAndWhite[4], referenceBlackAndWhite[5], 127);
this.converter = new YCbCrToRgbConverter(coefficients[0], coefficients[1], coefficients[2]);
}
private static void Decode2DScanline(T6BitReader bitReader, bool whiteIsZero, CcittReferenceScanline referenceScanline, Span <byte> scanline)
{
int width = scanline.Length;
bitReader.StartNewRow();
// 2D Encoding variables.
int a0 = -1;
byte fillByte = whiteIsZero ? (byte)0 : (byte)255;
// Process every code word in this scanline.
int unpacked = 0;
while (true)
{
// Read next code word and advance pass it.
bool isEol = bitReader.ReadNextCodeWord();
// Special case handling for EOL.
if (isEol)
{
// If a TIFF reader encounters EOFB before the expected number of lines has been extracted,
// it is appropriate to assume that the missing rows consist entirely of white pixels.
scanline.Fill(whiteIsZero ? (byte)0 : (byte)255);
break;
}
// Update 2D Encoding variables.
int b1 = referenceScanline.FindB1(a0, fillByte);
// Switch on the code word.
int a1;
switch (bitReader.Code.Type)
{
case CcittTwoDimensionalCodeType.None:
TiffThrowHelper.ThrowImageFormatException("ccitt compression parsing error, could not read a valid code word.");
break;
case CcittTwoDimensionalCodeType.Pass:
int b2 = referenceScanline.FindB2(b1);
scanline.Slice(unpacked, b2 - unpacked).Fill(fillByte);
unpacked = b2;
a0 = b2;
break;
case CcittTwoDimensionalCodeType.Horizontal:
// Decode M(a0a1)
bitReader.ReadNextRun();
int runLength = (int)bitReader.RunLength;
if (runLength > (uint)(scanline.Length - unpacked))
{
TiffThrowHelper.ThrowImageFormatException("ccitt compression parsing error");
}
scanline.Slice(unpacked, runLength).Fill(fillByte);
unpacked += runLength;
fillByte = (byte)~fillByte;
// Decode M(a1a2)
bitReader.ReadNextRun();
runLength = (int)bitReader.RunLength;
if (runLength > (uint)(scanline.Length - unpacked))
{
TiffThrowHelper.ThrowImageFormatException("ccitt compression parsing error");
}
scanline.Slice(unpacked, runLength).Fill(fillByte);
unpacked += runLength;
fillByte = (byte)~fillByte;
// Prepare next a0
a0 = unpacked;
break;
case CcittTwoDimensionalCodeType.Vertical0:
a1 = b1;
scanline.Slice(unpacked, a1 - unpacked).Fill(fillByte);
unpacked = a1;
a0 = a1;
fillByte = (byte)~fillByte;
bitReader.SwapColor();
break;
case CcittTwoDimensionalCodeType.VerticalR1:
a1 = b1 + 1;
scanline.Slice(unpacked, a1 - unpacked).Fill(fillByte);
unpacked = a1;
a0 = a1;
fillByte = (byte)~fillByte;
bitReader.SwapColor();
break;
case CcittTwoDimensionalCodeType.VerticalR2:
a1 = b1 + 2;
scanline.Slice(unpacked, a1 - unpacked).Fill(fillByte);
unpacked = a1;
a0 = a1;
fillByte = (byte)~fillByte;
bitReader.SwapColor();
break;
case CcittTwoDimensionalCodeType.VerticalR3:
a1 = b1 + 3;
scanline.Slice(unpacked, a1 - unpacked).Fill(fillByte);
unpacked = a1;
a0 = a1;
fillByte = (byte)~fillByte;
bitReader.SwapColor();
break;
case CcittTwoDimensionalCodeType.VerticalL1:
a1 = b1 - 1;
scanline.Slice(unpacked, a1 - unpacked).Fill(fillByte);
unpacked = a1;
a0 = a1;
fillByte = (byte)~fillByte;
bitReader.SwapColor();
break;
case CcittTwoDimensionalCodeType.VerticalL2:
a1 = b1 - 2;
scanline.Slice(unpacked, a1 - unpacked).Fill(fillByte);
unpacked = a1;
a0 = a1;
fillByte = (byte)~fillByte;
bitReader.SwapColor();
break;
case CcittTwoDimensionalCodeType.VerticalL3:
a1 = b1 - 3;
scanline.Slice(unpacked, a1 - unpacked).Fill(fillByte);
unpacked = a1;
a0 = a1;
fillByte = (byte)~fillByte;
bitReader.SwapColor();
break;
default:
throw new NotSupportedException("ccitt extensions are not supported.");
}
// This line is fully unpacked. Should exit and process next line.
if (unpacked == width)
{
break;
}
if (unpacked > width)
{
TiffThrowHelper.ThrowImageFormatException("ccitt compression parsing error, unpacked data > width");
}
}
}
/// <summary>
/// Read the next run of pixels.
/// </summary>
public void ReadNextRun()
{
if (this.terminationCodeFound)
{
this.IsWhiteRun = !this.IsWhiteRun;
this.terminationCodeFound = false;
}
// Initialize for next run.
this.Reset();
// We expect an EOL before the first data.
this.ReadEolBeforeFirstData();
// A code word must have at least 2 bits.
this.Value = this.ReadValue(MinCodeLength);
do
{
if (this.CurValueBitsRead > this.maxCodeLength)
{
TiffThrowHelper.ThrowImageFormatException("ccitt compression parsing error: invalid code length read");
}
bool isMakeupCode = this.IsMakeupCode();
if (isMakeupCode)
{
if (this.IsWhiteRun)
{
this.RunLength += this.WhiteMakeupCodeRunLength();
}
else
{
this.RunLength += this.BlackMakeupCodeRunLength();
}
this.isStartOfRow = false;
this.Reset(resetRunLength: false);
continue;
}
bool isTerminatingCode = this.IsTerminatingCode();
if (isTerminatingCode)
{
// Each line starts with a white run. If the image starts with black, a white run with length zero is written.
if (this.isStartOfRow && this.IsWhiteRun && this.WhiteTerminatingCodeRunLength() == 0)
{
this.Reset();
this.isStartOfRow = false;
this.terminationCodeFound = true;
this.RunLength = 0;
break;
}
if (this.IsWhiteRun)
{
this.RunLength += this.WhiteTerminatingCodeRunLength();
}
else
{
this.RunLength += this.BlackTerminatingCodeRunLength();
}
this.terminationCodeFound = true;
this.isStartOfRow = false;
break;
}
uint currBit = this.ReadValue(1);
this.Value = (this.Value << 1) | currBit;
if (this.IsEndOfScanLine)
{
this.StartNewRow();
}
}while (!this.IsEndOfScanLine);
this.isFirstScanLine = false;
}
