ImageCodec

This is the final project of Video Signal Processing in NTHU, 2015, Spring, and the document is just a set of supplementary materials. It simply demonstrates how to use these source files to encode/decode an image, and how to integrate/compile the project. Because it is complex, I can only show how to use as clearly as possible. If you have any problem, please send me an e-mail. (tony123930@yahoo.com.tw)

Requirements

Mac OSX [recommended] or UNIX (terminal and shell script used)
Xcode-build-tools [recommended] or g++ compiler
Matlab [recommended] or YUV viewer

Note that Windows has not been tested yet, so it might take lots of time encoding an image. Please wait for it, thanks.
If you are trying to run this project on the platform other than Mac OSX, please make sure your executable (.out, .exe) is in the directory /ImageCodec/

Project Structure

Root: /ImageCodec/
Code: /ImageCodec/code/, /ImageCodec/libs/
Data: /ImageCodec/data/
Generated: /ImageCodec/results/
Report: /ImageCodec/report/

Note that if user does not arrange files followed the structure mentioned above, it might cause some unknown errors.

Quick Start

Directly running the sample code

run cd ~/{YOUR_DIR}/ImageCodec/

Configuration in the sample code

check the file /ImageCodec/code/ImageCodec_Demo.cpp

#define CONSTRAINT_BY_PSNR 0
#define CONSTRAINT_BY_BITRATE 1
#define SKIP_ENCODING -1

using namespace std;
int main(int argc, const char * argv[]) {

	int constWay = {Config}; // 
						<-- can be
						CONSTRAINT_BY_PSNR    : Use PSNR as constraint
						CONSTRAINT_BY_BITRATE : Use bitrate as constraint
						SKIP_ENCODING         : Skip encoding

	int opt = {Config}; // <-- can be
									0: 1_1536x1024.yuv
									1: 2_1024x768.yuv
									2: 3_1000x728.yuv
									3: 4_1000x1504.yuv

and

	if (constWay == CONSTRAINT_BY_PSNR) {
		ss << PATHS[opt+4]; ss << "bitstream1.bin";
		ImageCodec::encodeTo(ss.str())->withImage(img)->withMinPSNR({Config})->run();
		ss.str(""); ss.clear(); ss << PATHS[opt+4]; ss << "bitstream2.bin";
		ImageCodec::encodeTo(ss.str())->withImage(img)->withMinPSNR({Config})->run();
		ss.str(""); ss.clear(); ss << PATHS[opt+4]; ss << "bitstream3.bin";
		ImageCodec::encodeTo(ss.str())->withImage(img)->withMinPSNR({Config})->run();
	} else if (constWay == CONSTRAINT_BY_BITRATE) {
		ss << PATHS[opt+4]; ss << "bitstream1.bin";
		ImageCodec::encodeTo(ss.str())->withImage(img)->withMaxBitrate({Config})->run();
		ss.str(""); ss.clear(); ss << PATHS[opt+4]; ss << "bitstream2.bin";
		ImageCodec::encodeTo(ss.str())->withImage(img)->withMaxBitrate({Config})->run();
		ss.str(""); ss.clear(); ss << PATHS[opt+4]; ss << "bitstream3.bin";
		ImageCodec::encodeTo(ss.str())->withImage(img)->withMaxBitrate({Config})->run();
	}

Replace the annotation {Config} with your specific configurations.
run ./run.sh under /ImageCodec/

Do the following commands on the terminal
1. run chmod +x ./run.sh
2. key in your pwd
3. run ./run.sh
Use Matlab code to convert YUV to PNG
- run genImage under /ImageCodec/ on Matlab terminal
Check the output files in /ImageCodec/results/

Encoding an image

This API gives 2 ways to encode an image.

Specific upper bound of bitrate

YUVImage* img = YUVImage::import({image_path})
						->withFormat({image_format})
						->withSize({image_width}, {image_height});
PerformancePackage::load(img->getName());
ImageCodec::encodeTo({target_path})->withImage(img)->withMaxBitrate({max_bitrate})->run();

e.g.

YUVImage* img = YUVImage::import("./1_1536x1024.yuv")
						->withFormat(YUVImage::FORMAT_4_2_0)
						->withSize(1536, 1024);
PerformancePackage::load(img->getName());
ImageCodec::encodeTo("./bitstream.bin")->withImage(img)->withMaxBitrate(0.75)->run();
PerformancePackage::save();

Specific lower bound of PSNR

YUVImage* img = YUVImage::import({image_path})
						->withFormat({image_format})
						->withSize({image_width}, {image_height});
PerformancePackage::load(img->getName());
ImageCodec::encodeTo({target_path})->withImage(img)->withMinPSNR({min_PSNR})->run();
PerformancePackage::save();

e.g.

YUVImage* img = YUVImage::import("./1_1536x1024.yuv")
						->withFormat(YUVImage::FORMAT_4_2_0)
						->withSize(1536, 1024);
PerformancePackage::load(img->getName());
ImageCodec::encodeTo("./bitstream.bin")->withImage(img)->withMinPSNR(28)->run();
PerformancePackage::save();

Decoding an image

Decoding a compressed file is easy.

 ImageCodec::decode({bitstream_path})->saveTo({target_path})->run();

e.g.

 ImageCodec::decode("./bitstream.bin")->saveTo("./decompressed.yuv")->run();

Obtaining PSNR

Importing 2 images and then call the following API.

 double PSNR = img1->calPSNR(img2);

e.g.

 YUVImage* img1 = YUVImage::import("./1_1536x1024.yuv")
 						->withFormat(YUVImage::FORMAT_4_2_0)
 						->withSize(1536, 1024);
 YUVImage* img2 = YUVImage::import("./decompressed.yuv")
 						->withFormat(YUVImage::FORMAT_4_2_0)
 						->withSize(1536, 1024);
 double PSNR = img1->calPSNR(img2);

Obtaining Bitrate

Importing the original image, and then give the path of compressed file.

 double bitrate = img->calBitrate({bitstream_path});

e.g.

 YUVImage* img = YUVImage::import("./1_1536x1024.yuv")
 						->withFormat(YUVImage::FORMAT_4_2_0)
 						->withSize(1536, 1024);
 double bitrate = img->calBitrate("./bitstream.bin");

Coding System

Level 1: main coding system.

Level 2: optionally applied, for compensating PSNR.

Work Flow

Define the searching space. ( O(dsr x mk x pid x qres), very large! )
Use all parameters to encode the file.
Evaluate the bitrate and PSNR.
Submit the result to ParameterPackage
Find the best parameters set under specific constraint.

Bitstream Format (top-bottom, left-right)

Solution of slow parameters searching

To save the time re-searching same parameters at same image, an database/controller has been programmed for saving these parameters. It is /ImageCodec/libs/PerformancePackage.h:

the parameters will be saved in /ImageCodec/libs/PerformancePackageCache/, that's why this project should be runned at the appropriate directory. (to avoid some potential problems)

the database is programmed as singleton, which can be identified with 'name'. In this project, the parameters are stored in the database named from YUVImage::getName()

i.e.

 YUVImage* image = YUVImage::import(mImgPath)
 								->withSize(mWidth, mHeight)
 								->withFormat(YUVImage::FORMAT_4_2_0);
 PerformancePackage::load(image->getName());

APIs List (only description and partial usage so far)

ImageCodec.h (642)

Main component of this project: to encode/decode a file.

Encoding

 ImageCodec::encodeTo({target_path})
 			->withImage({your_image})
 			->withMaxBitrate({max_bitrate})
 			->run();

 ImageCodec::encodeTo({target_path})
 			->withImage({your_image})
 			->withMinPSNR({min_PSNR})
 			->run();

Decoding

 ImageCodec::decode({bitstream_path})
 			->saveTo({decompressed_path})
 			->run();

YUVImage.h (520)

An object that contains lots of functions/properties that an image has.

Importing an image

 YUVImage* image = 
 		YUVImage::import({image_path})
 				->withSize({image_width}, {image_height})
 				->withFormat(YUVImage::FORMAT_4_2_0);

Initiate an empty image

 YUVImage* image = YUVImage::emptyImage({assigned_path}, 
 										{image_width}, 
 										{image_height}, 
 										{image_format});

Save the image into a file
```
 image->exportTo({tartget_path});
```

Properties

 image->getWidth(DataLayer::Y); image->getHeight(DataLayer::Cr);
 image->getDataSize(DataLayer::Cb);
 image->getDataSize(); // get total size of image
 image->getFormat(); // FORMAT_4_2_0 | FORMAT_4_2_2 | FORMAT_4_4_4
 image->getPath();
 image->getName();

Data getters & setters

 image->getYDataAt<int>(x, y);
 image->getCbDataAt<short>(x, y);
 image->getCrDataAt<long>(x, y);
 image->setYDataAt(x, y, (short)v);
 image->setCbDataAt(x, y, (short)v);
 image->setCrDataAt(x, y, (short)v);

Circular Addition/Subtraction

 YUVImage* image3 = image1->add(image2);
 YUVImage* image4 = image1->diff(image2);

Evaluate difference between two images
```
 double PSNR = image1->calPSNR(image2);
```

Evaluate the compressed bitrate

 double bitrate = image1->calBitrate({bitstream_path});

YUVImageFactory.h (150)

A toolbox to process YUVImage: to apply k-means clustering.

Clustering the image

 YUVImageFactory* factory = 
 			YUVImageFactory::initWithImage(image)
 								->useQuantization()
 								->withYUVLevels({Y_clusters}, {U_clusters}, {V_clusters})
 								->compress();

After clustering, all data in the image refer to cluster ID rather than magnitude. The clustered image with cluster ID can be obtained with YUVImage* symbolImg = factory->getSymbolImage(), and the clustered image with magnitude can be obtained with YUVImage* clusteredImg = factory->getImage()

Information after clustering

 factory->getYLevel(); // get # of Y_clusters
 factory->getYSymbolAt(n); // get the n^th center of Y
 factory->getULevel(); factory->getUSymbolAt(n);
 factory->getVLevel(); factory->getVSymbolAt(n);

ImagePredictor.h (139)

A toolbox to process YUVImage: to generate predicted residual image with a specific predictor ID.
- Directly getting a residual image
```
 YUVImage* resImg = ImagePredictor::predictResidual(image, predictorID);
```
- Use circular subtraction (e.g. 1 cirSubtr_5 7 = (1-7) % 5 = 4)
```
 int circularN[3] = {64, 16, 8};
 YUVImage* resImg = ImagePredictor::predictResidual(image, predictorID, circularN);
```
- Predictor ID: (only 1-8 used)

Transform.h (65)

A toolbox to do discrete cosine transform: 4x4-block supported so far. [not used]

Transformation of a vector

 int v1[4] = {1, -1, 2, -2};
 Transform::dct4<int>(v1);
 
 short v2[4] = {11, 1, -2, 1};
 Transform::idct4<short>(v2);

Transformation of multiple vectors

 int v1[12] = {1, 2, 1, 2, -1, 3, 15, 10, 0, 2, -3, -5};
 Transform::dct4<int>(v1, 3);
 
 long v2[8] = {1254, -4, 11, 19, 28, 3, 2, 0};
 Transform::idct4<long>(v2, 2);

KmeansFactory.h (176)

A toolbox to do k-means clustering.

KmeansFactory<T>: all data are stored in T type.
KmeansInfo<T, centerT>: all centers are stored in centerT type.

 int data[65536] = {1, 4, 2, 8, 10, 16, ... };
 KmeansFactory<int>* factory = KmeansFactory<int>::getInstance();
 KmeansInfo<int, int>* info = factory->withRawData(data, 65536)
 									->clusterInto(4096)
 									->run<int>();

HuffmanTable.h (298)

An object able to construct a canonical Huffman table with specific contents data.

HuffmanTable<T>: all data are stored in T type.

 char data[1024] = {0, 5, 123, ... };
 HuffmanTable<short>* table = HuffmanTable::initWithSize(256)
 											->withData(data, 1024);

Get maximal word length and entries value

 int WL_max = table->getMaxWordLength();
 for (int i = 0; i < WL_max; i++)
 	int nEntries = table->getNumEntriesWithWordLength(i+1);

Get symbol/probability at specific index

 Symbol<T>* symb = table->getSymbolAt(n);
 double p = table->getProbabilityAt(n);

GolombRiceTable.h (213)

An object able to construct a Golomb-Rice table. [not used]
- GolombRiceTable<T>: all data are stored in T type
```
 GolombRiceTable<int>* table = GolombRiceTable<int>::initWithSize({size})
 													->withGroupSize({group_size})
 													->init();
```
- Other getters are similar to HuffmanTable's.

PerformancePackage.h (316)

A central controller/database to manage the efficiency and its corresponded parameters set.

Getting database with a specific name

 PerformancePackage* pkg = PerformancePackage::getInstance(name);

Submitting a 'tried parameters set' to database

 CompressionParameters* 
 		cp = Builder()->withArea(imageArea)
 					  ->withDownSampleScale(wscale, hscale)
 					  ->withMk_YUV(mk_y, mk_u, mk_v)
 					  ->withPredictorID(predictorID)
 					  ->withKmeansTableSize(N_k)
 					  ->withMk_TABLE(mk_table)
 					  ->withMaxWordLength(WL_max)
 					  ->withKmeansTableBitrate(kmeansTableBitrate)
 					  ->withAdjustBitrate(adjustBitrate)
 					  ->withResidualQuantizationConst(Q_res)
 					  ->withPSNR(PSNR)
 					  ->withAdjust(isWithAdjust);
 pkg->submit(cp);

After searching all parameters, the database should eliminate some higher-bitrate and lower-PSNR (higher cost, lower efficiency) parameters set.
```
 pkg->anneal();
```
Save all data into the disk
```
 PerformancePackage::save();
```
Load data with a specific name
```
 PerformancePackage::load(name);
```

BitReader.h (93)

A toolbox to read a file in bits level.

Opening an input stream

 BitReader* reader = BitReader::open({stream_path});

Reading data (big endian)

 char v = reader->read(); // read a bit
 char* v = reader->read(size);
 long v = reader->read<long>(15); // read 15 bits and store in long
 short v = reader->read<short>(3);

Properties

 int restBits = reader->remains();
 int size = reader->getFileSize(); // in terms of bits not bytes

DO NOT FORGET TO CLOSE INPUT STREAM! (because it is singleton.)
```
 reader->close();
```

BitWriter.h (101)

A toolbox to write a file in bits level.

Opening the output stream

 BitWriter* writer = BitWriter::open({stream_path});

Writing data

 writer->write(0);
 
 char v[5] = {0, 1, 1, 1, 0};
 writer->write(v, 5);
 
 int k = 18;
 writer->write<int>(k, 7); // write '0010010'

DO NOT FORGET TO CLOSE OUTPUT STREAM! (because it is singleton.)
```
 writer->close();
```

Symbol.h (77)

An object that contains lots of functions/properties that a symbol has.

Symbol<T>: the value of the symbol is stored in T type

Getters

 Symbol<short>* s = new Symbol<short>(v);
 short value = s->getValue();
 std::vector<char> word = s->getWord();
 string wordStr = s->getWordString();
 int wordCount = s->getWordSize();

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Repository files navigation

ImageCodec

Requirements

Project Structure

Quick Start

Directly running the sample code

Encoding an image

Decoding an image

Obtaining PSNR

Obtaining Bitrate

Coding System

Work Flow

Bitstream Format (top-bottom, left-right)

Solution of slow parameters searching

APIs List (only description and partial usage so far)

ImageCodec.h (642)

YUVImage.h (520)

YUVImageFactory.h (150)

ImagePredictor.h (139)

Transform.h (65)

KmeansFactory.h (176)

HuffmanTable.h (298)

GolombRiceTable.h (213)

PerformancePackage.h (316)

BitReader.h (93)

BitWriter.h (101)

Symbol.h (77)

Total: 2790 lines

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Name		Name	Last commit message	Last commit date
Latest commit History 18 Commits
code		code
data		data
libs		libs
report		report
results		results
.gitignore		.gitignore
BT709_l.mat		BT709_l.mat
README.md		README.md
genImages.m		genImages.m
run.sh		run.sh
yuv2rgb.m		yuv2rgb.m

HW-Lee/ImageCodec

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Repository files navigation

ImageCodec

Requirements

Project Structure

Quick Start

Directly running the sample code

Encoding an image

Decoding an image

Obtaining PSNR

Obtaining Bitrate

Coding System

Work Flow

Bitstream Format (top-bottom, left-right)

Solution of slow parameters searching

APIs List (only description and partial usage so far)

ImageCodec.h (642)

YUVImage.h (520)

YUVImageFactory.h (150)

ImagePredictor.h (139)

Transform.h (65)

KmeansFactory.h (176)

HuffmanTable.h (298)

GolombRiceTable.h (213)

PerformancePackage.h (316)

BitReader.h (93)

BitWriter.h (101)

Symbol.h (77)

Total: 2790 lines

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