Enhanced compression time

Compressor/Compressor.cpp

@@ -1,62 +1,34 @@
 #include "Compressor.h"
 
-Compressor::Compressor(int threshold) {
-	this->threshold = threshold;
+Compressor::Compressor() {
+
 }
 
 Compressor::~Compressor() {
-	imgMatrix.deallocate();
+
 }
 
 //
 // Compression functions
 //
 
-void Compressor::compress(const string& imagePath, const string& outputPath) {
-	cout << "Loading image..." << endl;
-	loadImage(imagePath);
-	cout << "Compressing..." << endl;
-	encodeData();
-	cout << "Saving compressed file..." << endl;
-	saveCompressedFile(outputPath);
-}
-
-void Compressor::loadImage(const string& path) {
-	// Load colored image from file
-	cv::Mat rgbMat = imread(path, CV_LOAD_IMAGE_COLOR);
-
-	// Check for invalid input
-	if (rgbMat.empty() || !rgbMat.data) {
-		string errorMessage = "Could not load the image at: " + path;
-		throw exception(errorMessage.c_str());
-	}
-
-	// Get image size
-	rows = rgbMat.rows;
-	cols = rgbMat.cols;
-
-	// Convert BGR to Gray
-	cv::cvtColor(rgbMat, imgMatrix, CV_BGR2GRAY);
-}
-
-void Compressor::encodeData() {
+void Compressor::compress(const cv::Mat& imageMat, vector<uchar>& outputBytes) {
+	// Clear previous records
 	compressedBytes.clear();
 	compressedSizes.clear();
 
 	// Store image rows count
-	compressedSizes.push_back(encodeToBase256(rows));
+	compressedSizes.push_back(encodeToBase256(imageMat.rows));
 
 	// Store image cols count
-	compressedSizes.push_back(encodeToBase256(cols));
+	compressedSizes.push_back(encodeToBase256(imageMat.cols));
 
 	// Store image pixels
 	int cnt = 0;
-	bool pixel, prv = true;
-	for (int i = 0; i < rows; ++i) {
-		for (int j = 0; j < cols; ++j) {
-			pixel = ((int)imgMatrix.at<uchar>(i, j) > this->threshold);
-
-			if (prv == pixel) {
+	bool prv = true;
+	for (int i = 0; i < imageMat.rows; ++i) {
+		for (int j = 0; j < imageMat.cols; ++j) {
+			if (prv == imageMat.at<bool>(i, j)) {
 				++cnt;
 			}
 			else {
@@ -70,9 +42,9 @@ void Compressor::encodeData() {
 
 	// Store compression meta-data
 	encodeMetaData();
-	/*for (int i = 0; i < compressedSizes.size(); ++i) {
-		compressedImage.push_back(compressedSizes[i]);
-	}*/
+
+	// Pass compressed data to function caller
+	outputBytes.swap(compressedBytes);
 }
 
 void Compressor::encodeMetaData() {
@@ -110,101 +82,38 @@ int Compressor::encodeToBase256(int number) {
 	return cnt;
 }
 
-void Compressor::saveCompressedFile(const string& path) {
-	ofstream fout(path, ofstream::binary);
-
-	if (!fout.is_open()) {
-		string errorMessage = "Could not load the file at: " + path;
-		throw exception(errorMessage.c_str());
-	}
-
-	fout.write((char*)compressedBytes.data(), compressedBytes.size());
-
-	fout.close();
-}
-
 //
 // Extraction functions
 //
 
-void Compressor::extract(const string& compressedFilePath, const string& outputPath) {
-	cout << "Loading compressed file..." << endl;
-	loadCompressedFile(compressedFilePath);
-	cout << "Extracting..." << endl;
-	decodeData();
-	cout << "Saving image..." << endl;
-	saveImage(outputPath);
-}
-
-void Compressor::loadCompressedFile(const string& path) {
-	ifstream fin(path, ifstream::binary);
-
-	if (!fin.is_open()) {
-		string errorMessage = "Could not load the file at: " + path;
-		throw exception(errorMessage.c_str());
-	}
-
-	// Get file size
-	fin.seekg(0, fin.end);
-	int fileSize = fin.tellg();
-	fin.seekg(0, fin.beg);
+void Compressor::extract(vector<uchar>& compressedBytes, cv::Mat& outputImage) {
+	// Pass data to compressor object
+	this->compressedBytes.swap(compressedBytes);
 
-	// Read all data
-	compressedBytes.resize(fileSize);
-	fin.read((char*)compressedBytes.data(), fileSize);
-
-	fin.close();
-}
-
-void Compressor::decodeData() {
-	// Retrieve image meta-data
-	compressedSizes.clear();
-	int bytesCnt = 0;
-	int dataIdx = 0, sizeIdx = -1, idx = -1;
-	int n = compressedBytes.size();
-	while (n >= 0 && n > bytesCnt) {
-		int cnt = (compressedBytes[--n] & 63);
-		int len = (compressedBytes[n] >> 6) + 1;
-		bytesCnt += cnt * len;
-
-		for (int i = 0; i < cnt; ++i) {
-			compressedSizes.push_back(len);
-		}
-	}
+	// Retrieve compression meta-data
+	decodeMetaData();
 
-	/*compressedSizes.clear();
-	int bytesCnt = 0;
 	int dataIdx = 0, sizeIdx = -1;
-	int n = compressedImage.size();
-	while (n >= 0 && n > bytesCnt) {
-		bytesCnt += (int)compressedImage[--n];
-		compressedSizes.push_back(compressedImage[n]);
-	}
-	reverse(compressedSizes.begin(), compressedSizes.end());*/
-
-	if (n != bytesCnt) {
-		throw exception("Could not extract the given file");
-	}
 
 	// Retrieve image rows count
-	rows = decodeFromBase256(dataIdx, compressedSizes[++sizeIdx]);
+	int rows = decodeFromBase256(dataIdx, compressedSizes[++sizeIdx]);
 	dataIdx += compressedSizes[sizeIdx];
 
 	// Retrieve image cols count
-	cols = decodeFromBase256(dataIdx, compressedSizes[++sizeIdx]);
+	int cols = decodeFromBase256(dataIdx, compressedSizes[++sizeIdx]);
 	dataIdx += compressedSizes[sizeIdx];
 
 	// Retrieve image pixels
-	imgMatrix = cv::Mat(rows, cols, CV_8U);
-	int i = 0, j = 0;
-	int cnt;
+	outputImage = cv::Mat(rows, cols, CV_8U);
+	int i = 0, j = 0, cnt;
 	bool color = true;
-	while (dataIdx < n) {
+
+	for (int k = 2; k < compressedSizes.size(); ++k) {
 		cnt = decodeFromBase256(dataIdx, compressedSizes[++sizeIdx]);
 		dataIdx += compressedSizes[sizeIdx];
 
 		while (cnt--) {
-			imgMatrix.at<uchar>(i, j) = color ? 255 : 0;
+			outputImage.at<uchar>(i, j) = (color ? 255 : 0);
 
 			if (++j >= cols) {
 				++i;
@@ -216,6 +125,27 @@ void Compressor::decodeData() {
 	}
 }
 
+void Compressor::decodeMetaData() {
+	compressedSizes.clear();
+
+	int bytesCnt = 0;
+	int n = compressedBytes.size();
+
+	while (n >= 0 && n > bytesCnt) {
+		int cnt = (compressedBytes[--n] & 63);
+		int len = (compressedBytes[n] >> 6) + 1;
+		bytesCnt += cnt * len;
+
+		for (int i = 0; i < cnt; ++i) {
+			compressedSizes.push_back(len);
+		}
+	}
+
+	if (n != bytesCnt) {
+		throw exception("Could not extract the given file");
+	}
+}
+
 int Compressor::decodeFromBase256(int idx, int size) {
 	idx += size;
 	int num = 0;
@@ -226,15 +156,4 @@ int Compressor::decodeFromBase256(int idx, int size) {
 	}
 
 	return num;
-}
-
-void Compressor::saveImage(const string& path) {
-	//Mat image(rows, cols, CV_8UC3);
-
-	/*int idx = -1;
-	for (int i = 0; i < rows; ++i)
-	for (int j = 0; j < cols; ++j)
-	image.at<Vec3b>(i, j) = (binaryImage[++idx] ? Vec3b(255, 255, 255) : Vec3b(0, 0, 0));*/
-
-	imwrite(path, imgMatrix);
 }

Compressor/Compressor.h

@@ -11,25 +11,20 @@
 #include <opencv2/highgui/highgui.hpp>
 
 // Custom libraries
-//#include "Utility.h"
 using namespace cv;
 using namespace std;
 
 class Compressor
 {
-public:
-	int rows;
-	int cols;
-	int threshold;
+private:
 	vector<int> compressedSizes;
 	vector<unsigned char> compressedBytes;
-	cv::Mat imgMatrix;
 
 public:
 	/**
 	 * Constructor
 	 */
-	Compressor(int threshold);
+	Compressor();
 
 	/**
 	 * Destructor
@@ -39,24 +34,14 @@ class Compressor
 	/**
 	 * Compress the given black & white jpg image
 	 */
-	void compress(const string& imagePath, const string& outputPath);
+	void compress(const cv::Mat& imageMat, vector<uchar>& outputBytes);
 
 	/**
 	 * Extract the given compressed file to a black & white jpg image
 	 */
-	void extract(const string& compressedFilePath, const string& outputPath);
+	void extract(vector<uchar>& compressedBytes, cv::Mat& outputImage);
 
 private:
-	/**
-	 * Loads grayscaled image from the given path into a matrix
-	 */
-	void loadImage(const string& path);
-
-	/**
-	 * Encode the loaded image data and save it to compressedBytes vector
-	 */
-	void encodeData();
-
 	/**
 	 * Encode meta-data needed in decompression process
 	 */
@@ -70,29 +55,14 @@ class Compressor
 	int encodeToBase256(int number);
 
 	/**
-	 * Save the compress data to the given path
+	 * Decode image compressed meta-data needed in decompression process
 	 */
-	void saveCompressedFile(const string& path);
-
-	/**
-	 * Load the compress data from the given path
-	 */
-	void loadCompressedFile(const string& path);
-
-	/**
-	 * Decode the loaded file data into a binary image
-	 */
-	void decodeData();
+	void decodeMetaData();
 
 	/**
 	 * Convert the given size of bytes from compressedBytes vector starting from idx
 	 * from base 256 to decimal.
 	 * Return the converted integer
 	 */
 	int decodeFromBase256(int idx, int size);
-
-	/**
-	 * Save the loaded image with the given url
-	 */
-	void saveImage(const string& path);	
 };

Compressor/Directory.h

@@ -7,7 +7,7 @@ using namespace std;
 /**
  * Returns a list of files (name, extension) in the given directory
  */
-inline void GetFilesInDirectory(vector<pair<string, string>>& files, const string& directory) {
+inline void getFilesInDirectory(const string& directory, vector<pair<string, string>>& files) {
 	// Make sure to change the following command to the corresponding
 	// one on your operating system when using Linux or MAC
 	string s = "dir " + directory + "b > dirs.txt";