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jpegdecode.cpp
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jpegdecode.cpp
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#include "jpegdecode.h"
#include <iostream>
#include <iomanip>
#include <QDebug>
#include <QtEndian>
#include <ctime>
#define DEBUGLEVEL 1
#define BENCHMARK
const double pi=3.1415926535897932384626433832795;
JpegDecode::JpegDecode(QFile &file) : zigZagStart(0), zigZagEnd(63), adobeColorModel(Format::YCBCR), losslessFormat(false) {
this->imagePtr = ImageStatePtr(new ImageState(file.fileName()));
if (!file.open(QFile::ReadOnly)) throw "Can't open file";
readFile(file);
file.close();
#ifdef BENCHMARK
cout << "Huffman "<<huffmanTime<<" ms, ZigZag "<<zigZagTime<<" ms, Quantize "<<quantizeTime<<" ms, IDCT "<<idctTime<<" ms, Add Block "<<addBlockTime<<" ms"<<endl;
cout << "TOTAL: " << (huffmanTime + zigZagTime + quantizeTime + idctTime + addBlockTime) << " ms"<<endl;
#endif
imagePtr->activeLayer()->updatePreview();
}
void JpegDecode::readFile(QFile &file) {
unsigned char ff, marker;
// Is this a JPEG file?
file.read((char*)&ff, sizeof(ff));
file.read((char*)&marker, sizeof(ff));
if (ff != 0xff || marker != 0xd8)
throw "This is not a JPEG file";
bool endOfImage=false;
while (!file.atEnd()) {
file.read((char*)&ff, sizeof(ff));
if (ff != 0xff) {
qDebug() << "0xFF expected but found "<<ff<<" at pos "<<file.pos();
continue;
}
file.read((char*)&marker, sizeof(ff));
#if DEBUGLEVEL>1
cout << "Found marker "<<hex<<int(marker) <<dec<< " pos "<<file.pos()<< endl;
#endif
switch (marker) {
case 0xd8: // SOI = Start Of Image
if (file.pos() != 2)
qDebug() << "Start of image (D8) found inside file?";
break;
case 0xd9: // EOI = End Of Image
endOfImage = true;
break;
// 0xe0 - 0xef : APPn = Application specific segments?
case 0xe0:
case 0xe1:
case 0xe2:
case 0xe3:
case 0xe4:
case 0xe5:
case 0xe6:
case 0xe7:
case 0xe8:
case 0xe9:
case 0xea:
case 0xeb:
case 0xec:
case 0xed:
case 0xee:
case 0xef:
readAppSegment(file, marker);
break;
case 0xc0: // SOF = Start Of Frame
case 0xc1:
case 0xc2:
case 0xc3:
case 0xc5:
case 0xc6:
case 0xc7:
case 0xc8:
case 0xc9:
case 0xca:
case 0xcb:
case 0xcd:
case 0xce:
case 0xcf:
readFrameHeader(file, marker);
break;
case 0xc4: // DHT = Define Huffman Tables
readHuffmanTables(file);
break;
case 0xcc: // DAC = Define Arithmetic Coding
readArithmeticCoding(file);
break;
case 0xdb: // DQT = Define Quantization Tables
readQuantizationTables(file);
break;
case 0xdc: // DNL = Define Number of Lines
// DNL is always 4 bytes long
// It is only used if a scan has different number of lines from previous scan (progressive?)
// [ ITU-T T.81, chapter B.2.5 ]
// If you find a progressive JPEG with this feature, please implement
for (int i=0; i<4; i++)
file.read((char*)&ff, sizeof(ff));
break;
case 0xdd: // DRI = Define Restart Interval
// DRI is always 4 bytes long
// We are currently just ignoring restart markers
for (int i=0; i<4; i++)
file.read((char*)&ff, sizeof(ff));
break;
case 0xde: // DHP = Define Hierarchical Progression
case 0xdf: // EXP = Expand Reference Components
throw "Hierarchical JPEG not supported yet";
case 0xfe: // COM = Comment
readComments(file);
break;
case 0xda: // SOS = Start Of Scan
readScanHeader(file);
// Scan starts immediately after header
readImageData(file);
break;
default:
qDebug() << "Unknown marker "<<marker<<" - lets ignore and hope for the best...";
}
if (endOfImage) break;
}
if (!endOfImage)
qDebug() << "File ended prematurely.";
dumpMetaData();
}
void JpegDecode::readMetaDataJFIF(QFile &picture) {
metadata["JPEG format"] = "JPEG/JFIF";
#if DEBUGLEVEL>1
qDebug() << "Read metadata JFIF";
#endif
unsigned char c1,c2;
picture.read((char*)&c1, sizeof(c1));
picture.read((char*)&c2, sizeof(c2));
metadata["JFIF version"] = QString("%1.%2").arg(int(c1)).arg(int(c2));
picture.read((char*)&c1, sizeof(c1));
unsigned short res1, res2;
picture.read((char*)&res1, sizeof(res1));
picture.read((char*)&res2, sizeof(res2));
res1 = qFromBigEndian(res1);
res2 = qFromBigEndian(res2);
if (c1==0)
metadata["Resolution"] = QString("%1x%2 pixels").arg(res1).arg(res2);
else if (c1==1)
metadata["Resolution"] = QString("%1x%2 DPI").arg(res1).arg(res2);
else if (c1==2)
metadata["Resolution"] = QString("%1x%2 DPcm").arg(res1).arg(res2);
picture.read((char*)&c1, sizeof(c1));
picture.read((char*)&c2, sizeof(c2));
if (c1>0 && c2>0) {
metadata["Thumbnail format"] = "Uncompressed RGB";
metadata["Thumbnail size"] = QString("%1x%2").arg(int(c1)).arg(int(c2));
thumbnail.resize(3*c1*c2);
for (int i=0; i < 3*c1*c2; i++) {
picture.read((char*)&c1, sizeof(c1));
thumbnail[i] = c1;
}
}
}
void JpegDecode::readMetaDataJFXX(QFile &picture, int headerLength) {
metadata["JPEG format"] = "JPEG/JFXX";
#if DEBUGLEVEL>1
qDebug() << "Read metadata JXFF";
#endif
unsigned char tf,tw,th;
picture.read((char*)&tf, sizeof(tf));
if (tf==0x10) {
metadata["Thumbnail format"] = "JPEG/JIF";
thumbnail.resize(headerLength - 1); // Substract the TF byte that was just read
for (int i=0; i < headerLength - 1; i++) {
picture.read((char*)&tw, sizeof(tw));
thumbnail[i] = tw;
}
} else {
picture.read((char*)&tw, sizeof(tw));
picture.read((char*)&th, sizeof(th));
if (tw>0 && th>0) {
metadata["Thumbnail size"] = QString("%1x%2").arg(int(tw)).arg(int(th));
int thumbLen = 0;
if (tf==0x11) {
metadata["Thumbnail format"] = "Paletted";
thumbLen = 768 + tw*th;
}
if (tf==0x11) {
metadata["Thumbnail format"] = "Uncompressed RGB";
thumbLen = 3*tw*th;
}
for (int i=0; i < thumbLen; i++) {
picture.read((char*)&tw, sizeof(tw));
thumbnail[i] = tw;
}
}
}
}
void JpegDecode::readAppSegment(QFile &picture, unsigned char marker) {
// Known application segments
// http://www.ozhiker.com/electronics/pjmt/jpeg_info/app_segments.html
// http://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/JPEG.html
const char* segmentTypes[11] = { "JFIF", "JFXX", "EXIF", "Exif", "http://ns.adobe.com/xap/1.0/", "ICC_PROFILE", "META", "Meta", "Ducky", "Photoshop 3.0", "Adobe" };
char data[30];
char* ptr=data;
unsigned short len;
picture.read((char*)&len, sizeof(len));
len = qFromBigEndian(len) - 2; // Two bytes for len are included in len value
bool found=false;
switch (marker) {
case 0xe0:
if (len >= 5) {
for (int i=0; i<5; i++)
picture.read(ptr++, sizeof(char));
if (strncmp(data, segmentTypes[0], 5) == 0) {
readMetaDataJFIF(picture);
return;
}
else if (strncmp(data, segmentTypes[1], 5) == 0) {
readMetaDataJFXX(picture, len-5);
return;
}
len -= 5;
}
break;
case 0xe1:
if (len >= 5) {
for (int i=0; i<5; i++)
picture.read(ptr++, sizeof(char));
if (strncmp(data, segmentTypes[2], 5) == 0 || strncmp(data, segmentTypes[3], 5) == 0) {
//readMetaDataExif(picture, headerLength); // TODO
// Parsing Exif data is in fact parsing a whole TIFF file...
qDebug() << "EXIF not supported yet...";
found = true;
} else if (len >= 28) {
for (int i=0; i<23; i++)
picture.read(ptr++, sizeof(char));
if (strncmp(data, segmentTypes[4], 23) == 0) {
qDebug() << "Adobe XMP (eXtensible Metadata Platform) not supported yet...";
found = true;
}
len -= 23;
}
len -= 5;
}
break;
case 0xe2:
if (len >= 12) {
for (int i=0; i<12; i++)
picture.read(ptr++, sizeof(char));
if (strncmp(data, segmentTypes[5], 12) == 0) {
qDebug() << "ICC profiles not supported...";
found = true;
}
len -= 12;
}
break;
case 0xe3:
if (len >= 5) {
for (int i=0; i<5; i++)
picture.read(ptr++, sizeof(char));
if (strncmp(data, segmentTypes[6], 5) == 0 || strncmp(data, segmentTypes[7], 5) == 0) {
//readMetaDataExif(picture, headerLength); // TODO
// Parsing Exif data is in fact parsing a whole TIFF file...
qDebug() << "EXIF not supported yet...";
found = true;
}
len -= 5;
}
break;
case 0xec:
if (len >= 6) {
for (int i=0; i<6; i++)
picture.read(ptr++, sizeof(char));
if (strncmp(data, segmentTypes[8], 6) == 0) {
// There is nothing in the "Ducky" tag that I can use, and my samples don't match description at
// http://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/APP12.html#Ducky
metadata["Photoshop 'Save for Web'"] = "yes";
len -= 6;
found = true;
} else {
// Apparently APP12 (0xEC) is otherwise used as a comment
char* text = new char[len];
char* tmp=text;
for (int i=0; i<len; i++)
picture.read(tmp++, sizeof(char));
*tmp = '\0';
metadata["APP12 Comment"] = QString(text);
delete[] text;
return;
}
}
break;
case 0xed:
if (len >= 14) {
for (int i=0; i<14; i++)
picture.read(ptr++, sizeof(char));
if (strncmp(data, segmentTypes[9], 14) == 0) {
qDebug() << "Adobe Photoshop(R) metadata not supported...";
found = true;
}
len -= 14;
}
break;
case 0xee:
if (len >= 6) {
for (int i=0; i<6; i++)
picture.read(ptr++, sizeof(char));
if (strncmp(data, segmentTypes[10], 6) == 0) {
// Adobe metadata - helps us detect CMYK and YCCK images
unsigned char cc;
for (int i=0; i<6; i++)
picture.read ((char*)&cc, sizeof(cc));
if (cc == 0)
adobeColorModel = Format::CMYK; // It can also be RGB if there are three components!
else if (cc == 1)
adobeColorModel = Format::YCBCR;
else if (cc == 2)
throw "YCCK color model currently not supported!";
return;
}
len -= 6;
}
break;
}
if (!found)
qDebug() << "Unsupported Application segment, marker"<<marker<<len;
unsigned char c;
for (int i=0; i<len; i++)
picture.read ((char*)&c, sizeof(c));
}
void JpegDecode::readComments(QFile &picture) {
static int commentNo = 1;
unsigned short len;
picture.read((char*)&len, sizeof(len));
len = qFromBigEndian(len);
char* text = new char[len];
char* tmp=text;
for (int i=0; i<len-2; i++)
picture.read(tmp++, sizeof(char));
*tmp = '\0';
metadata[QString("Comment %1").arg(commentNo++)] = QString(text);
delete[] text;
}
void JpegDecode::readFrameHeader(QFile &picture, unsigned char marker) {
if (marker == 0xc0) {
metadata["Subformat"] = "Baseline DCT";
} else if (marker == 0xc1) {
metadata["Subformat"] = "Extended DCT";
// The only difference is support for multiple Huffman tables and 12-bit precision
// which we will support with baseline as well
} else if (marker == 0xc2) {
metadata["Subformat"] = "Progressive DCT";
//throw "Progressive JPEG not supported yet";
} else if (marker == 0xc3) {
metadata["Subformat"] = "Lossless";
losslessFormat = true;
} else if (marker == 0xc9) {
metadata["Subformat"] = "Arithmetic DCT";
throw "Arithmetic coding JPEG not supported yet";
} else if (marker == 0xca) {
metadata["Subformat"] = "Arithmetic progressive DCT";
throw "Arithmetic coding progressive JPEG not supported yet";
} else if (marker == 0xcb) {
metadata["Subformat"] = "Arithmetic lossless";
losslessFormat = true;
throw "Arithmetic coding lossless JPEG not supported yet";
} else {
throw "Unknown JPEG subformat - frame header not found.";
}
// Header length
unsigned short headerLength;
picture.read((char*)&headerLength, sizeof(headerLength));
headerLength = qFromBigEndian(headerLength);
picture.read((char*)&precision,sizeof(precision));
metadata["Precision"] = QString("%1").arg(int(precision));
//Taking picture height and width. These informations are stored in two bytes for each dimension
unsigned short pictureHeight, pictureWidth;
picture.read ((char*)&pictureHeight, sizeof(pictureHeight));
picture.read ((char*)&pictureWidth, sizeof(pictureWidth));
pictureHeight = qFromBigEndian(pictureHeight);
pictureWidth = qFromBigEndian(pictureWidth);
//Taking information for number of components and components data
//Every component has 4 information. ComponentID, Horizontal sampling, Vertical Sampling, and Quantization table ID
unsigned char numberOfComponents;
picture.read((char*)&numberOfComponents,sizeof(numberOfComponents));
if (headerLength != numberOfComponents*3 + 8)
qDebug() << "Bad SOF header length: expected"<<(numberOfComponents*3+8)<<"but given"<<headerLength;
metadata["Number of components"] = QString("%1").arg(int(numberOfComponents));
for (int i=0;i<numberOfComponents;i++) {
unsigned char componentData[3];
picture.read ((char*)componentData,sizeof(componentData));
if (losslessFormat) { // Lossless format doesn't use quantization tables
QuantizationTable fake(false, false);
Component a(componentData[0], (componentData[1]>>4), (componentData[1] & 0x0F), componentData[2], fake);
this->components.push_back(a);
continue;
}
bool foundTable=false;
for (unsigned int x=0;x<quantizationTables.size();x++) {
if (quantizationTables[x].tableID==componentData[2]) {
Component a(componentData[0], (componentData[1]>>4), (componentData[1] & 0x0F), componentData[2], quantizationTables[x]);
this->components.push_back(a);
foundTable=true;
}
}
if (!foundTable) {
qDebug() << "Component "<<componentData[0]<<" specifies unknown quantization table - skipping.";
}
}
// Calculate scaling factors - much easier to work with
int maxHFactor=1, maxVFactor=1;
for (uint i=0; i<components.size(); i++) {
if (components[i].HFactor > maxHFactor) maxHFactor = components[i].HFactor;
if (components[i].VFactor > maxVFactor) maxVFactor = components[i].VFactor;
}
for (uint i=0; i<components.size(); i++) {
components[i].HScale = maxHFactor / components[i].HFactor;
components[i].VScale = maxVFactor / components[i].VFactor;
}
if (maxHFactor == 1 && maxVFactor == 1)
hasSubSampling = false;
else
hasSubSampling = true;
// Set number of components to ImageState
Format f = imagePtr->format();
// Default JPEG color model
f.setColorModel(Format::YCBCR);
if (precision <= 8)
f.setColorDepth(24);
else
// 12-bit is not directly supported by EtfShop, use 16-bit instead
f.setColorDepth(48);
if (numberOfComponents == 3) {
// Note: Adobe nonstandard header uses code 0 to specify both CMYK and RGB
if (adobeColorModel == Format::CMYK) {
f.setColorModel(Format::RGB);
metadata["Color model"] = "RGB";
}
}
else if (numberOfComponents == 4) {
// Adobe proprietary extension
if (adobeColorModel == Format::CMYK) {
f.setColorModel(Format::CMYK);
metadata["Color model"] = "CMYK";
if (precision <= 8)
f.setColorDepth(32);
else
f.setColorDepth(64);
f.setEncodingType(Format::COMPONENTWORD); // This is faster
} else {
qDebug() << "Specified 4 components, but no Adobe header!";
}
}
else if (numberOfComponents == 1) {
f.setColorModel(Format::GRAYSCALE);
if (precision <= 8)
f.setColorDepth(8);
else
f.setColorDepth(16);
// f.setEncodingType(Format::COMPONENTWORD); // This is faster
}
else {
qDebug() << "Specified "<<numberOfComponents<<" components, but no Adobe header!";
// We will use JPEG standard (24-bit YCbCr) and hope that this is a glitch...
}
imagePtr->setFormat(f);
imagePtr->setSize(pictureWidth, pictureHeight);
imagePtr->activeLayer()->setSize(pictureWidth, pictureHeight);
#if DEBUGLEVEL>0
qDebug()<<"Image height is: "<<pictureHeight<<" and image width is: "<< pictureWidth <<endl;
#endif
}
void JpegDecode::readQuantizationTables(QFile &picture) {
//First two bytes from this point is Quantization Table length
//Third byte is divided in two nibbles.
//First nible is Quantization element table precision 8 or 16 bits
//Second nibble is Quantization table destination identifier
//Next 64 bytes are Quantization table element if the size of elements are 8 bits, or 128 bytes if the size of elements is two bytes
unsigned short tableLength;//Two bytes
unsigned char tableOptions=0;
unsigned char tableIdentifier=0;
unsigned char sizeOfElements=0;
int tableData[64]; // 64 elements per table
picture.read ((char*)&tableLength, sizeof(tableLength));
tableLength = qFromBigEndian(tableLength);
int m=2;
while(m<tableLength) {
picture.read ((char*)&tableOptions, sizeof(tableOptions));
sizeOfElements = tableOptions>>4; // Higher 4 bits of byte
tableIdentifier = tableOptions & 0x0F; // Lower 4 bits of byte
QuantizationTable t(false, false);
t.tableID = tableIdentifier;
// Elements are represented by 8 bits
if (sizeOfElements == 0) {
unsigned char el;
for (int i=0; i<64; i++) {
picture.read ((char*)&el, sizeof(el));
tableData[i] = el;
}
m=m+65;
}
// 16-bit elements
else if (sizeOfElements==1) {
unsigned short el;
for (int i=0; i<64; i++) {
picture.read ((char*)&el, sizeof(el));
el = qFromBigEndian(el);
tableData[i] = el;
}
m=m+129;
}
inverseZigZagCoding (tableData, t.quantizationTableData);
quantizationTables.push_back(t);
#if DEBUGLEVEL>0
qDebug() << "Read quantization table "<<tableIdentifier<<" depth "<<sizeOfElements;
#endif
}
}
void JpegDecode::readHuffmanTables(QFile &picture) {
//First two bytes are Huffman table length
//Third byte is separated in two nibbles. First nibble is Table Class, second nibble is destination identifier or ID
//Next 16 bytes are number of elements coded with 1-16 bits
unsigned short tableLength; // First two bytes-table length
unsigned char tableID = 0; // Specifies one of component: 0 for luminance and 1 for chrominance
unsigned char tableClass = 0; // Specifies is it DC element or AC element of table. 0-DC element 1-AC element
unsigned char huffmanTableOptions = 0; // I will decompose this in two nibbles
picture.read ((char*)&tableLength, sizeof(tableLength));
tableLength = qFromBigEndian(tableLength);
int m=2;
while (m < tableLength) {
picture.read((char*)&huffmanTableOptions,sizeof(huffmanTableOptions));
m++;
tableID = huffmanTableOptions & 0x0F;
tableClass = huffmanTableOptions >> 4;
// Looking for tableID in tables
HuffmanTable* table = 0;
for (uint i=0; i<huffmanTables.size(); i++) {
HuffmanTable* t = huffmanTables[i];
if (t->tableID == tableID && t->tableClass == tableClass) {
table = huffmanTables[i];
break;
}
}
// Not found, create a new table
if (table == 0) {
table = new HuffmanTable();
table->tableID = tableID;
table->tableClass = tableClass;
huffmanTables.push_back(table);
}
unsigned char codeLengths[16];
for(int i=0;i<16;i++)
codeLengths[i]=0;
unsigned long int code=0;//Huffman code which will be connected with element
unsigned char element=0;//Read element from file
// Read 16 bytes for number of elements which are coded by 1-16 bits
picture.read ((char*)codeLengths, sizeof(codeLengths));
m+=16;
for (int i=0; i<16; i++) { //We iterate through every element
if (codeLengths[i]==0) { //If code length is 0, then we continue because no element is coded wiht "i" bits
code *= 2; // When tree depth changes, we add additional bit, and shift code one place left
continue;
}
for (int j=0; j<codeLengths[i]; j++) { //If there is at least one element coded with "i" bits, then we have to assign code to it
picture.read ((char*)&element, sizeof(element));
m++;
table->codes[element] = code;
table->codeLengths[element] = i+1;
code++; //Elements on the same tree depth have code incremented by one
}
code *= 2; //When tree depth changes, we add additional bit, and shift code one place left
}
#if DEBUGLEVEL>0
qDebug() << "Read Huffman table ID: " << tableID << "class" << tableClass;
#endif
}
}
void JpegDecode::readArithmeticCoding(QFile &picture) {
// Arithmetic coding not supported yet
// Just skip data
unsigned short len;
unsigned char c;
picture.read ((char*)&len, sizeof(len));
len = qFromBigEndian(len);
for (int i=0; i<len-2; i++)
picture.read ((char*)&c, sizeof(c));
qDebug() << "DAC found (0xCC) - Arithmetic coding not supported yet";
}
void JpegDecode::readScanHeader(QFile &picture) {
/* --- Entropy-coded image data
After FF DA marker starts header followed by data
Header contains:
- Header length (not data, just header)
- Number of color components e.g. 3 for Y'CbCr, 4 for CMYK
- Component IDs (2 bytes per component)
- ZigZag definition (3 bytes)
After header immediately comes data ending with marker FF D9
*/
if (components.size() == 0) {
throw "SOF header not present or specifies 0 components.";
}
unsigned short headerLength;
unsigned char numberOfComponents;
picture.read ((char*)&headerLength, sizeof(headerLength));
picture.read ((char*)&numberOfComponents, sizeof(numberOfComponents));
headerLength = qFromBigEndian(headerLength);
if (headerLength != numberOfComponents*2 + 6)
qDebug() << "Bad SOS header length: expected"<<(numberOfComponents*2+6)<<"but given"<<headerLength;
if (numberOfComponents != this->components.size()) {
qDebug() << "Number of components in SOS header is" << numberOfComponents << "but in SOF header is" << this->components.size();
qDebug() << "We will trust SOF header, but this probably wont work :(";
numberOfComponents = this->components.size();
}
if (numberOfComponents > ETF_FORMAT_MAX_COMPONENTS) {
qDebug() << "Specified"<<numberOfComponents<<"components, maximum is "<<ETF_FORMAT_MAX_COMPONENTS;
numberOfComponents = ETF_FORMAT_MAX_COMPONENTS;
}
// Read components and tables
for (int i=0; i < numberOfComponents; i++) {
unsigned char componentID, tableID;
picture.read ((char*)&componentID, sizeof(componentID));
picture.read ((char*)&tableID, sizeof(tableID));
// Check component in components list
if (this->components[i].componentID != componentID) {
qDebug() << "Component ID in SOS header is" << componentID << "but in SOF header is" << this->components[i].componentID;
qDebug() << "We will trust SOF header";
}
// Find AC and DC Huffman table in tables list
unsigned char tableDC = tableID >> 4;
unsigned char tableAC = tableID & 0x0F;
componentTablesDC[i] = componentTablesAC[i] = 0;
for (uint j=0; j<huffmanTables.size(); j++) {
HuffmanTable* t = huffmanTables[j];
if (t->tableID == tableDC && t->tableClass == 0)
componentTablesDC[i] = t;
if (t->tableID == tableAC && t->tableClass == 1)
componentTablesAC[i] = t;
}
// Huffman tables not found
if (componentTablesDC[i] == 0) {
// Get first usable table
for (uint j=0; j<huffmanTables.size(); j++) {
HuffmanTable* t = huffmanTables[j];
if (t->tableClass == 0) {
componentTablesDC[i] = t;
break;
}
}
if (componentTablesDC[i] == 0)
throw "File contains no DC Huffman tables!";
qDebug() << "SOS header specifies inexistant Huffman table" << tableDC << " - using " << componentTablesDC[i]->tableID;
}
if (componentTablesAC[i] == 0) {
// Get first usable table
for (uint j=0; j<huffmanTables.size(); j++) {
HuffmanTable* t = huffmanTables[j];
if (t->tableClass == 1) {
componentTablesAC[i] = t;
break;
}
}
if (componentTablesAC[i] == 0) {
// throw "File contains no AC Huffman tables!"; // Can happen in progressive JPEG!
componentTablesAC[i] = componentTablesDC[i];
}
qDebug() << "SOS header specifies inexistant Huffman table" << tableAC << " - using " << componentTablesAC[i]->tableID;
}
}
// Start and end point for zig-zag coding
picture.read ((char*)&zigZagStart, sizeof(zigZagStart));
picture.read ((char*)&zigZagEnd, sizeof(zigZagEnd));
// Bit approximation for progressive JPEG - TODO!
unsigned char dummy;
picture.read ((char*)&dummy, sizeof(dummy));
approximationH = dummy >> 4;
approximationL = dummy & 0x0F;
}
void JpegDecode::readImageData(QFile &file) {
uint currentComponent = 0;
int counter2 = 1; // Counter for chroma subsampling
int row[64], row2[8][8], row3[8][8];
int blkNo = 0;
// Statistics of last DC value
for (uint i=0; i<components.size(); i++)
previousDC[i]=0;
if (losslessFormat) {
// Predictor requires to hold last line in memory
for (uint i=0; i<components.size(); i++)
scanLineCache[i] = new int[imagePtr->width()];
}
// Initialize data for addBlock method
rawImagePointers[0] = (uchar*) imagePtr->activeLayer()->getData();
lineBytes = imagePtr->width() * components.size();
if (precision == 12) lineBytes *= 2;
maxSample = pow(2, precision)-1;
// scanline is aligned to the 32-bit boundary
if (lineBytes % 4 != 0)
lineBytes += 4 - lineBytes%4;
for (uint i=0; i<components.size(); i++) {
currentX[i] = currentY[i] = 0;
rawImagePointers[i] = rawImagePointers[0] + i;
currentBlockHFactor[i] = currentBlockVFactor[i] = 0;
}
// Initialize data for IDCT method
for (int i=0; i<106; i++)
cosine[i] = cos(i*pi/16);
for(int i=0;i<8;i++){
for(int j=0;j<8;j++){
for(int u=0;u<8;u++){
for(int v=0;v<8;v++){
int index = i*512 + j*64 + u*8 + v;
double tmp = 1024 * cosine[(2*i+1)*u] * cosine[(2*j+1)*v];
if (u==0 && v==0)
tmp /= 8;
else if (u>0 && v>0)
tmp /= 4;
else
tmp *= 0.1767766952966368811;
coefficients[index] = tmp;
}
}
}
}
// Benchmarking
clock_t t1, t2, t3, t4, t5, t6;
huffmanTime = zigZagTime = quantizeTime = idctTime = addBlockTime = 0;
#if DEBUGLEVEL>0
qDebug()<<"Start of scan";
#endif
endOfFile = false;
while (!endOfFile) {
#if DEBUGLEVEL>1
qDebug()<<"--- Huffman read block "<<blkNo<<" component "<<currentComponent;
#endif
t1=clock();
readHuffmanBlock(file, row, currentComponent);
t2=clock();
if (losslessFormat) {
t3=t4=t5=t2;
addLossless(row, currentComponent);
t6=clock();
} else {
// DC predictor
previousDC[currentComponent] = row[0];
inverseZigZagCoding (row, row2);
t3=clock();
multiplyWithQuantizationTable (row2, currentComponent);
t4=clock();
IDCT (row2, row3);
t5=clock();
// Adding data to ImageState
if (hasSubSampling)
addBlockSubsampling(row3, currentComponent);
else
addBlock(row3, currentComponent);
t6=clock();
}
// Is there component subsampling ?
if (counter2 < this->components[currentComponent].HFactor * this->components[currentComponent].VFactor)
counter2++;
else {
counter2 = 1;
currentComponent++;
if (currentComponent == components.size()) currentComponent=0;
}
blkNo++;
// Benchmarking
#ifdef BENCHMARK
huffmanTime += (t2-t1) / (CLOCKS_PER_SEC / 1000);
zigZagTime += (t3-t2) / (CLOCKS_PER_SEC / 1000);
quantizeTime += (t4-t3) / (CLOCKS_PER_SEC / 1000);
idctTime += (t5-t4) / (CLOCKS_PER_SEC / 1000);
addBlockTime += (t6-t5) / (CLOCKS_PER_SEC / 1000);
if (blkNo % 10000 == 0) {
qDebug() << "Huffmannn "<<huffmanTime<<" ms, ZigZag "<<zigZagTime<<" ms, Quantize "<<quantizeTime<<" ms, IDCT "<<idctTime<<" ms, Add Block "<<addBlockTime<<" ms";
}
#endif
}
if (losslessFormat) {
// Predictor requires to hold last line in memory
for (uint i=0; i<components.size(); i++)
delete[] scanLineCache[i];
}
#if DEBUGLEVEL>0
qDebug()<<"End of scan";
#endif
}
bool JpegDecode::readMoreData(QFile &picture, unsigned int &data, unsigned int ¤tDataLength) {
unsigned char binaryData;
// Detect errors
if (currentDataLength > 24) { // Unsigned int can hold at most 32 = 24+8 bits
cout << "ERROR: Code value not found in Huffman table: "<<data<<endl;
// Truncate data one by one bit in hope that we will eventually find a correct code
data = data - ((data >> (currentDataLength-1)) << (currentDataLength-1));
currentDataLength--;
return true;
}
if (picture.read((char*)&binaryData, sizeof binaryData) == 0)
return false; // End of file
// We read byte and put it in low 8 bits of variable data
if (binaryData == 0xFF) {
data = (data << 8) + binaryData;
currentDataLength += 8; // Increase current data length for 8 because we read one new byte
if (picture.read((char*)&binaryData, sizeof binaryData) == 0)
return false;
// End of Image marker
if (binaryData == 0xd9) {
// Drop 0xFF from data
data = data >> 8;
currentDataLength -= 8;
#if DEBUGLEVEL>1
cout << "End of image marker"<<endl;
#endif
return false;
}
// Restart marker means data goes blank
if (binaryData >= 0xd0 && binaryData <= 0xd7) {
#if DEBUGLEVEL>1
cout << "Restart marker"<<endl;
#endif
data = 0;
currentDataLength = 0;
for (uint i=0; i<components.size(); i++)
previousDC[i]=0;