public DecodedJpeg Decode()
{
// The frames in this jpeg are loaded into a list. There is
// usually just one frame except in heirarchial progression where
// there are multiple frames.
JPEGFrame frame = null;
// The restart interval defines how many MCU's we should have
// between the 8-modulo restart marker. The restart markers allow
// us to tell whether or not our decoding process is working
// correctly, also if there is corruption in the image we can
// recover with these restart intervals. (See RSTm DRI).
int resetInterval = 0;
bool haveMarker = false;
bool foundJFIF = false;
List <JpegHeader> headers = new List <JpegHeader>();
// Loop through until there are no more markers to read in, at
// that point everything is loaded into the jpegFrames array and
// can be processed.
while (true)
{
#region Switch over marker types
switch (marker)
{
case JPEGMarker.APP0:
// APP1 is used for EXIF data
case JPEGMarker.APP1:
// Seldomly, APP2 gets used for extended EXIF, too
case JPEGMarker.APP2:
case JPEGMarker.APP3:
case JPEGMarker.APP4:
case JPEGMarker.APP5:
case JPEGMarker.APP6:
case JPEGMarker.APP7:
case JPEGMarker.APP8:
case JPEGMarker.APP9:
case JPEGMarker.APP10:
case JPEGMarker.APP11:
case JPEGMarker.APP12:
case JPEGMarker.APP13:
case JPEGMarker.APP14:
case JPEGMarker.APP15:
// COM: Comment
case JPEGMarker.COM:
// Debug.WriteLine(string.Format("Extracting Header, Type={0:X}", marker));
JpegHeader header = ExtractHeader();
#region Check explicitly for Exif Data
if (header.Marker == JPEGMarker.APP1 && header.Data.Length >= 6)
{
byte[] d = header.Data;
if (d[0] == 'E' &&
d[1] == 'x' &&
d[2] == 'i' &&
d[3] == 'f' &&
d[4] == 0 &&
d[5] == 0)
{
// Exif. Do something?
}
}
#endregion
#region Check for Adobe header
if (header.Data.Length >= 5 && header.Marker == JPEGMarker.APP14)
{
string asText = UTF8Encoding.UTF8.GetString(header.Data, 0, 5);
if (asText == "Adobe")
{
// ADOBE HEADER. Do anything?
}
}
#endregion
headers.Add(header);
if (!foundJFIF && marker == JPEGMarker.APP0)
{
foundJFIF = TryParseJFIF(header.Data);
if (foundJFIF) // Found JFIF... do JFIF extension follow?
{
header.IsJFIF = true;
marker = jpegReader.GetNextMarker();
// Yes, they do.
if (marker == JPEGMarker.APP0)
{
header = ExtractHeader();
headers.Add(header);
}
else // No. Delay processing this one.
{
haveMarker = true;
}
}
}
break;
case JPEGMarker.SOF0:
case JPEGMarker.SOF2:
// SOFn Start of Frame Marker, Baseline DCT - This is the start
// of the frame header that defines certain variables that will
// be carried out through the rest of the encoding. Multiple
// frames are used in a hierarchical system, however most JPEG's
// only contain a single frame.
// Progressive or baseline?
progressive = marker == JPEGMarker.SOF2;
jpegFrames.Add(new JPEGFrame());
frame = (JPEGFrame)jpegFrames[jpegFrames.Count - 1];
frame.ProgressUpdateMethod = new Action <long>(UpdateStreamProgress);
// Skip the frame length.
jpegReader.ReadShort();
// Bits percision, either 8 or 12.
frame.setPrecision(jpegReader.ReadByte());
// Scan lines (height)
frame.ScanLines = jpegReader.ReadShort();
// Scan samples per line (width)
frame.SamplesPerLine = jpegReader.ReadShort();
// Number of Color Components (channels).
frame.ComponentCount = jpegReader.ReadByte();
DecodeProgress.Height = frame.Height;
DecodeProgress.Width = frame.Width;
DecodeProgress.SizeReady = true;
if (DecodeProgressChanged != null)
{
DecodeProgressChanged(this, DecodeProgress);
}
// Add all of the necessary components to the frame.
for (int i = 0; i < frame.ComponentCount; i++)
{
byte compId = jpegReader.ReadByte();
byte sampleFactors = jpegReader.ReadByte();
byte qTableId = jpegReader.ReadByte();
byte sampleHFactor = (byte)(sampleFactors >> 4);
byte sampleVFactor = (byte)(sampleFactors & 0x0f);
frame.AddComponent(compId, sampleHFactor, sampleVFactor, qTableId);
}
break;
case JPEGMarker.DHT:
// DHT non-SOF Marker - Huffman Table is required for decoding
// the JPEG stream, when we receive a marker we load in first
// the table length (16 bits), the table class (4 bits), table
// identifier (4 bits), then we load in 16 bytes and each byte
// represents the count of bytes to load in for each of the 16
// bytes. We load this into an array to use later and move on 4
// huffman tables can only be used in an image.
int huffmanLength = (jpegReader.ReadShort() - 2);
// Keep looping until we are out of length.
int index = huffmanLength;
// Multiple tables may be defined within a DHT marker. This
// will keep reading until there are no tables left, most
// of the time there are just one tables.
while (index > 0)
{
// Read the identifier information and class
// information about the Huffman table, then read the
// 16 byte codelength in and read in the Huffman values
// and put it into table info.
byte huffmanInfo = jpegReader.ReadByte();
byte tableClass = (byte)(huffmanInfo >> 4);
byte huffmanIndex = (byte)(huffmanInfo & 0x0f);
short[] codeLength = new short[16];
for (int i = 0; i < codeLength.Length; i++)
{
codeLength[i] = jpegReader.ReadByte();
}
int huffmanValueLen = 0;
for (int i = 0; i < 16; i++)
{
huffmanValueLen += codeLength[i];
}
index -= (huffmanValueLen + 17);
short[] huffmanVal = new short[huffmanValueLen];
for (int i = 0; i < huffmanVal.Length; i++)
{
huffmanVal[i] = jpegReader.ReadByte();
}
// Assign DC Huffman Table.
if (tableClass == HuffmanTable.JPEG_DC_TABLE)
{
dcTables[(int)huffmanIndex] = new JpegHuffmanTable(codeLength, huffmanVal);
}
// Assign AC Huffman Table.
else if (tableClass == HuffmanTable.JPEG_AC_TABLE)
{
acTables[(int)huffmanIndex] = new JpegHuffmanTable(codeLength, huffmanVal);
}
}
break;
case JPEGMarker.DQT:
// DQT non-SOF Marker - This defines the quantization
// coeffecients, this allows us to figure out the quality of
// compression and unencode the data. The data is loaded and
// then stored in to an array.
short quantizationLength = (short)(jpegReader.ReadShort() - 2);
for (int j = 0; j < quantizationLength / 65; j++)
{
byte quantSpecs = jpegReader.ReadByte();
int[] quantData = new int[64];
if ((byte)(quantSpecs >> 4) == 0)
// Precision 8 bit.
{
for (int i = 0; i < 64; i++)
{
quantData[i] = jpegReader.ReadByte();
}
}
else if ((byte)(quantSpecs >> 4) == 1)
// Precision 16 bit.
{
for (int i = 0; i < 64; i++)
{
quantData[i] = jpegReader.ReadShort();
}
}
qTables[(int)(quantSpecs & 0x0f)] = new JpegQuantizationTable(quantData);
}
break;
case JPEGMarker.SOS:
Debug.WriteLine("Start of Scan (SOS)");
// SOS non-SOF Marker - Start Of Scan Marker, this is where the
// actual data is stored in a interlaced or non-interlaced with
// from 1-4 components of color data, if three components most
// likely a YCrCb model, this is a fairly complex process.
// Read in the scan length.
//ushort scanLen = jpegReader.ReadShort();
// Number of components in the scan.
byte numberOfComponents = jpegReader.ReadByte();
byte[] componentSelector = new byte[numberOfComponents];
for (int i = 0; i < numberOfComponents; i++)
{
// Component ID, packed byte containing the Id for the
// AC table and DC table.
byte componentID = jpegReader.ReadByte();
byte tableInfo = jpegReader.ReadByte();
int DC = (tableInfo >> 4) & 0x0f;
int AC = (tableInfo) & 0x0f;
frame.setHuffmanTables(componentID,
acTables[(byte)AC],
dcTables[(byte)DC]);
componentSelector[i] = componentID;
}
byte startSpectralSelection = jpegReader.ReadByte();
byte endSpectralSelection = jpegReader.ReadByte();
byte successiveApproximation = jpegReader.ReadByte();
#region Baseline JPEG Scan Decoding
if (!progressive)
{
frame.DecodeScanBaseline(numberOfComponents, componentSelector, resetInterval, jpegReader, ref marker);
haveMarker = true; // use resultant marker for the next switch(..)
}
#endregion
#region Progressive JPEG Scan Decoding
if (progressive)
{
frame.DecodeScanProgressive(
successiveApproximation, startSpectralSelection, endSpectralSelection,
numberOfComponents, componentSelector, resetInterval, jpegReader, ref marker);
haveMarker = true; // use resultant marker for the next switch(..)
}
#endregion
break;
case JPEGMarker.DRI:
jpegReader.BaseStream.Seek(2, System.IO.SeekOrigin.Current);
resetInterval = jpegReader.ReadShort();
break;
// Defines the number of lines. (Not usually present)
case JPEGMarker.DNL:
frame.ScanLines = jpegReader.ReadShort();
break;
// End of Image. Finish the decode.
case JPEGMarker.EOI:
if (jpegFrames.Count == 0)
{
throw new NotSupportedException("No JPEG frames could be located.");
}
else if (jpegFrames.Count == 1)
{
// Only one frame, JPEG Non-Heirarchial Frame.
byte[][,] raster = Image.CreateRaster(frame.Width, frame.Height, frame.ComponentCount);
IList <JpegComponent> components = frame.Scan.Components;
int totalSteps = components.Count * 3; // Three steps per loop
int stepsFinished = 0;
for (int i = 0; i < components.Count; i++)
{
JpegComponent comp = components[i];
comp.QuantizationTable = qTables[comp.quant_id].Table;
// 1. Quantize
comp.quantizeData();
UpdateProgress(++stepsFinished, totalSteps);
// 2. Run iDCT (expensive)
comp.idctData();
UpdateProgress(++stepsFinished, totalSteps);
// 3. Scale the image and write the data to the raster.
comp.writeDataScaled(raster, i, BlockUpsamplingMode);
UpdateProgress(++stepsFinished, totalSteps);
// Ensure garbage collection.
comp = null; GC.Collect();
}
// Grayscale Color Image (1 Component).
if (frame.ComponentCount == 1)
{
ColorModel cm = new ColorModel()
{
ColorSpace = ColorSpace.Gray, Opaque = true
};
image = new Image(cm, raster);
}
// YCbCr Color Image (3 Components).
else if (frame.ComponentCount == 3)
{
ColorModel cm = new ColorModel()
{
ColorSpace = ColorSpace.YCbCr, Opaque = true
};
image = new Image(cm, raster);
}
// Possibly CMYK or RGBA ?
else
{
throw new NotSupportedException("Unsupported Color Mode: 4 Component Color Mode found.");
}
// If needed, convert centimeters to inches.
Func <double, double> conv = x =>
Units == UnitType.Inches ? x : x / 2.54;
image.DensityX = conv(XDensity);
image.DensityY = conv(YDensity);
//height = frame.Height;
//width = frame.Width;
}
else
{
// JPEG Heirarchial Frame
throw new NotSupportedException("Unsupported Codec Type: Hierarchial JPEG");
}
break;
// Only SOF0 (baseline) and SOF2 (progressive) are supported by FJCore
case JPEGMarker.SOF1:
case JPEGMarker.SOF3:
case JPEGMarker.SOF5:
case JPEGMarker.SOF6:
case JPEGMarker.SOF7:
case JPEGMarker.SOF9:
case JPEGMarker.SOF10:
case JPEGMarker.SOF11:
case JPEGMarker.SOF13:
case JPEGMarker.SOF14:
case JPEGMarker.SOF15:
throw new NotSupportedException("Unsupported codec type.");
default: break; // ignore
}
#endregion switch over markers
if (haveMarker)
{
haveMarker = false;
}
else
{
try
{
marker = jpegReader.GetNextMarker();
}
catch (System.IO.EndOfStreamException)
{
break; /* done reading the file */
}
}
}
DecodedJpeg result = new DecodedJpeg(image, headers);
return(result);
}
public DecodedJpeg Decode()
{
JPEGFrame jPEGFrame = null;
int resetInterval = 0;
bool flag = false;
bool flag2 = false;
List <JpegHeader> list = new List <JpegHeader>();
while (true)
{
if (DecodeProgress.Abort)
{
return(null);
}
switch (marker)
{
case 224:
case 225:
case 226:
case 227:
case 228:
case 229:
case 230:
case 231:
case 232:
case 233:
case 234:
case 235:
case 236:
case 237:
case 238:
case 239:
case 254:
{
JpegHeader jpegHeader = ExtractHeader();
if (jpegHeader.Marker == 225 && jpegHeader.Data.Length >= 6)
{
byte[] data = jpegHeader.Data;
if (data[0] == 69 && data[1] == 120 && data[2] == 105 && data[3] == 102 && data[4] == 0)
{
_ = data[5];
}
}
if (jpegHeader.Data.Length >= 5 && jpegHeader.Marker == 238)
{
_ = (Encoding.UTF8.GetString(jpegHeader.Data, 0, 5) == "Adobe");
}
list.Add(jpegHeader);
if (flag2 || marker != 224)
{
break;
}
flag2 = TryParseJFIF(jpegHeader.Data);
if (flag2)
{
jpegHeader.IsJFIF = true;
marker = jpegReader.GetNextMarker();
if (marker == 224)
{
jpegHeader = ExtractHeader();
list.Add(jpegHeader);
}
else
{
flag = true;
}
}
break;
}
case 192:
case 194:
{
progressive = (marker == 194);
jpegFrames.Add(new JPEGFrame());
jPEGFrame = jpegFrames[jpegFrames.Count - 1];
jPEGFrame.ProgressUpdateMethod = UpdateStreamProgress;
jpegReader.ReadShort();
jPEGFrame.setPrecision(jpegReader.ReadByte());
jPEGFrame.ScanLines = jpegReader.ReadShort();
jPEGFrame.SamplesPerLine = jpegReader.ReadShort();
jPEGFrame.ComponentCount = jpegReader.ReadByte();
DecodeProgress.Height = jPEGFrame.Height;
DecodeProgress.Width = jPEGFrame.Width;
DecodeProgress.SizeReady = true;
if (this.DecodeProgressChanged != null)
{
this.DecodeProgressChanged(this, DecodeProgress);
if (DecodeProgress.Abort)
{
return(null);
}
}
for (int m = 0; m < jPEGFrame.ComponentCount; m++)
{
byte componentID = jpegReader.ReadByte();
byte num5 = jpegReader.ReadByte();
byte quantizationTableID = jpegReader.ReadByte();
byte sampleHFactor = (byte)(num5 >> 4);
byte sampleVFactor = (byte)(num5 & 0xF);
jPEGFrame.AddComponent(componentID, sampleHFactor, sampleVFactor, quantizationTableID);
}
break;
}
case 196:
{
int num2 = jpegReader.ReadShort() - 2;
while (num2 > 0)
{
byte num3 = jpegReader.ReadByte();
byte b = (byte)(num3 >> 4);
byte b2 = (byte)(num3 & 0xF);
short[] array = new short[16];
for (int j = 0; j < array.Length; j++)
{
array[j] = jpegReader.ReadByte();
}
int num4 = 0;
for (int k = 0; k < 16; k++)
{
num4 += array[k];
}
num2 -= num4 + 17;
short[] array2 = new short[num4];
for (int l = 0; l < array2.Length; l++)
{
array2[l] = jpegReader.ReadByte();
}
if (b == HuffmanTable.JPEG_DC_TABLE)
{
dcTables[b2] = new JpegHuffmanTable(array, array2);
}
else if (b == HuffmanTable.JPEG_AC_TABLE)
{
acTables[b2] = new JpegHuffmanTable(array, array2);
}
}
break;
}
case 219:
{
short num9 = (short)(jpegReader.ReadShort() - 2);
for (int num10 = 0; num10 < num9 / 65; num10++)
{
byte b5 = jpegReader.ReadByte();
int[] array4 = new int[64];
if ((byte)(b5 >> 4) == 0)
{
for (int num11 = 0; num11 < 64; num11++)
{
array4[num11] = jpegReader.ReadByte();
}
}
else if ((byte)(b5 >> 4) == 1)
{
for (int num12 = 0; num12 < 64; num12++)
{
array4[num12] = jpegReader.ReadShort();
}
}
qTables[b5 & 0xF] = new JpegQuantizationTable(array4);
}
break;
}
case 218:
{
jpegReader.ReadShort();
byte b3 = jpegReader.ReadByte();
byte[] array3 = new byte[b3];
for (int n = 0; n < b3; n++)
{
byte b4 = jpegReader.ReadByte();
byte num6 = jpegReader.ReadByte();
int num7 = (num6 >> 4) & 0xF;
int num8 = num6 & 0xF;
jPEGFrame.setHuffmanTables(b4, acTables[(byte)num8], dcTables[(byte)num7]);
array3[n] = b4;
}
byte startSpectralSelection = jpegReader.ReadByte();
byte endSpectralSelection = jpegReader.ReadByte();
byte successiveApproximation = jpegReader.ReadByte();
if (!progressive)
{
jPEGFrame.DecodeScanBaseline(b3, array3, resetInterval, jpegReader, ref marker);
flag = true;
}
if (progressive)
{
jPEGFrame.DecodeScanProgressive(successiveApproximation, startSpectralSelection, endSpectralSelection, b3, array3, resetInterval, jpegReader, ref marker);
flag = true;
}
break;
}
case 221:
jpegReader.BaseStream.Seek(2L, SeekOrigin.Current);
resetInterval = jpegReader.ReadShort();
break;
case 220:
jPEGFrame.ScanLines = jpegReader.ReadShort();
break;
case 217:
{
if (jpegFrames.Count == 0)
{
throw new NotSupportedException("No JPEG frames could be located.");
}
if (jpegFrames.Count > 1)
{
jPEGFrame = jpegFrames.OrderByDescending((JPEGFrame f) => f.Width * f.Height).FirstOrDefault();
}
byte[][,] raster = Image.CreateRaster(jPEGFrame.Width, jPEGFrame.Height, jPEGFrame.ComponentCount);
IList <JpegComponent> components = jPEGFrame.Scan.Components;
int stepsTotal = components.Count * 3;
int num = 0;
for (int i = 0; i < components.Count; i++)
{
JpegComponent jpegComponent = components[i];
jpegComponent.QuantizationTable = qTables[jpegComponent.quant_id].Table;
jpegComponent.quantizeData();
UpdateProgress(++num, stepsTotal);
jpegComponent.idctData();
UpdateProgress(++num, stepsTotal);
jpegComponent.writeDataScaled(raster, i, BlockUpsamplingMode);
UpdateProgress(++num, stepsTotal);
jpegComponent = null;
GC.Collect();
}
ColorModel colorModel;
if (jPEGFrame.ComponentCount == 1)
{
colorModel = default(ColorModel);
colorModel.colorspace = ColorSpace.Gray;
colorModel.Opaque = true;
ColorModel cm = colorModel;
image = new Image(cm, raster);
}
else
{
if (jPEGFrame.ComponentCount != 3)
{
throw new NotSupportedException("Unsupported Color Mode: 4 Component Color Mode found.");
}
colorModel = default(ColorModel);
colorModel.colorspace = ColorSpace.YCbCr;
colorModel.Opaque = true;
ColorModel cm2 = colorModel;
image = new Image(cm2, raster);
}
Func <double, double> func = (double x) => (Units != UnitType.Inches) ? (x / 2.54) : x;
image.DensityX = func((int)XDensity);
image.DensityY = func((int)YDensity);
break;
}
case 193:
case 195:
case 197:
case 198:
case 199:
case 201:
case 202:
case 203:
case 205:
case 206:
case 207:
throw new NotSupportedException("Unsupported codec type.");
}
if (flag)
{
flag = false;
}
else
{
try
{
marker = jpegReader.GetNextMarker();
}
catch (EndOfStreamException)
{
break;
}
}
}
return(new DecodedJpeg(image, list));
}