GasLeakDetector C++ library

v1.0.0

Table of contents

• Overview
• Versions
• Library files
• Key features and capabilities
• Supported pixel formats
• Library principles
• GasLeakDetector class description
  • GasLeakDetector class declaration
  • getVersion method
  • initVFilter method
  • setParam method
  • getParam method
  • executeCommand method
  • processFrame method
  • setMask method
  • encodeSetParamCommand method of VFilter class
  • encodeCommand method of VFilter class
  • decodeCommand method of VFilter class
  • decodeAndExecuteCommand method
• Data structures
  • VFilterCommand enum
  • VFilterParam enum
• VFilterParams class description
  • VFilterParams class declaration
  • Serialize VFilter params
  • Deserialize VFilter params
  • Read params from JSON file and write to JSON file
• Build and connect to your project
• Example
• Benchmark
• Demo application

Overview

GasLeakDetector C++ library amplifies subtle motion and temporal variations in digital video content. It implements Eulerian Video Magnification algorithms (optimized for Gas Leaking Detection scenario for thermal cameras). The library represents video filtering function and can be used not only for Gas Leaking Detection but for motion magnification. The library is implemented in C++ (C++17 standard). This library is suitable for various types of cameras (daylight, SWIR, MWIR and LWIR). Each instance of the GasLeakDetector C++ class object performs frame-by-frame processing of a video data stream, processing each video frame independently. The library is only intended for not moving (or moving slowly) cameras or for PTZ cameras when observing in a certain sector. The algorithm works only on one CPU core. The library depends on open source VFilter library (provides interface as well as defines data structures for various video filters implementation, source code included, Apache 2.0 license) and OpenCV (version >= 4.5, linked, Apache 2.0 license). Additionally demo application depends on open source SimpleFileDialog (provides dialog to open files, source code included, Apache 2.0 license).

Versions

Table 1 - Library versions.

Version	Release date	What’s new
1.0.0	24.02.2025	- First version.

Library files

The library supplied by source code only. The user would be given a set of files in the form of a CMake project (repository). The repository structure is shown below:

CMakeLists.txt ------------------- Main CMake file of the library.
3rdparty ------------------------- Folder with third-party libraries.
    CMakeLists.txt --------------- CMake file to include third-party libraries.
    VFilter ---------------------- Folder with VFilter library source code.
src ------------------------------ Folder with library source code.
    CMakeLists.txt --------------- CMake file of the library.
    GasLeakDetector.h ------------ Main library header file.
    GasLeakDetectorVersion.h.in -- File for CMake to generate version header.
    GasLeakDetector.cpp ---------- C++ class source file.
    impl ------------------------- Folder with implementation files.
        GasLeakDetectorImpl.cpp -- C++ implementation file.
        GasLeakDetectorImpl.h ---- Header file of the implementation.
demo ----------------------------- Folder for demo application files.
    CMakeLists.txt --------------- CMake file for demo application.
    3rdaprty --------------------- Folder with third-party libraries for demo application.
        CMakeLists.txt ----------- CMake file to include third-party libraries.
        SimpleFileDialog --------- Folder with SimpleFileDialog library source code.
    main.cpp --------------------- Source C++ file of demo application.
example -------------------------- Folder for simple example.
    CMakeLists.txt --------------- CMake file of example.
    main.cpp --------------------- Source C++ file of example,
benchmark ------------------------ Folder with benchmark application.
    CMakeLists.txt --------------- CMake file of benchmark application.
    main.cpp --------------------- Source C++ file of benchmark application.

Key features and capabilities

Table 2 - Key features and capabilities.

Parameter and feature	Description
Programming language	C++ (standard C++17) and using OpenCV (version >= 4.5).
Supported OS	Compatible with any operating system that supports the C++ compiler (C++17 standard) and OpenCV (version >= 4.5).
Movement type	The library is able to magnify any kind of movement, but it is best suitable for tiny moving objects that are hard to spot with unarmed eye, e.g. drone, gas leaking.
Supported pixel formats	GRAY, YUV24, YUYV, UYVY, NV12, NV21, YV12, YU12. The library uses pixels intensity for video processing. If the pixel format of the image doesn’t include intensity channel it should be converted to proper format before applying magnification.
Calculation speed	The processing time per video frame depends on the computing platform used. The processing time per video frame can be estimated with the demo application.
Type of algorithm	A modified Eulerian Video Magnification algorithm was implemented. Amplification factor can be dynamically changed by user to serve different requirements.
Working conditions	Algorithm implemented in the library is designed to work on fixed cameras (or moving slowly) with any background conditions.

Supported pixel formats

The Frame library which included in GasLeakDetector library contains Fourcc enum which defines supported pixel formats (Frame.h file). GasLeakDetector library supports only formats with intensity channel (GRAY, YUV24, YUYV, UYVY, NV12, NV21, YV12, YU12). The library uses the intensity channel for video processing. Fourcc enum declaration:

enum class Fourcc
{
    /// RGB 24bit pixel format.
    RGB24 = MAKE_FOURCC_CODE('R', 'G', 'B', '3'),
    /// BGR 24bit pixel format.
    BGR24 = MAKE_FOURCC_CODE('B', 'G', 'R', '3'),
    /// YUYV 16bits per pixel format.
    YUYV  = MAKE_FOURCC_CODE('Y', 'U', 'Y', 'V'),
    /// UYVY 16bits per pixel format.
    UYVY  = MAKE_FOURCC_CODE('U', 'Y', 'V', 'Y'),
    /// Grayscale 8bit.
    GRAY  = MAKE_FOURCC_CODE('G', 'R', 'A', 'Y'),
    /// YUV 24bit per pixel format.
    YUV24  = MAKE_FOURCC_CODE('Y', 'U', 'V', '3'),
    /// NV12 pixel format.
    NV12  = MAKE_FOURCC_CODE('N', 'V', '1', '2'),
    /// NV21 pixel format.
    NV21  = MAKE_FOURCC_CODE('N', 'V', '2', '1'),
    /// YU12 (YUV420) - Planar pixel format.
    YU12 = MAKE_FOURCC_CODE('Y', 'U', '1', '2'),
    /// YV12 (YVU420) - Planar pixel format.
    YV12 = MAKE_FOURCC_CODE('Y', 'V', '1', '2'),
    /// JPEG compressed format.
    JPEG  = MAKE_FOURCC_CODE('J', 'P', 'E', 'G'),
    /// H264 compressed format.
    H264  = MAKE_FOURCC_CODE('H', '2', '6', '4'),
    /// HEVC compressed format.
    HEVC  = MAKE_FOURCC_CODE('H', 'E', 'V', 'C')
};

Table 3 - Bytes layout of supported RAW pixel formats. Example of 4x4 pixels image.

YUV24	GRAY
YUYV	UYVY
NV12	NV21
YU12	YV12

Library principles

The filter algorithm is implemented with multi-hypothesis support, incorporating temporal filtering and signal amplification. The algorithm involves the following sequential steps:

1. Acquiring the source video frame and retrieve intensity channel.
2. Calculating pixel intensity values’ differences.
3. Filtrating signal and applying amplification.
4. Creating result image by applying proper pixels’ values to the intensity channel and then merged with incoming image.

The library is available as source code only. To utilize the library as source code, developers must incorporate the library files into their project. The usage sequence for the library is as follows:

1. Include the library files in the project.
2. Create an instance of the GasLeakDetector C++ class. If you need multiple parallel cameras processing you have to create multiple GasLeakDetector C++ class instances.
3. If necessary, modify the default library parameters using the setParam(…) method.
4. Create Frame class object for input frame.
5. Call the processFrame(…) method to magnify video data stream.

GasLeakDetector class description

GasLeakDetector class declaration

GasLeakDetector.h file contains GasLeakDetector class declaration:

namespace cr
{
namespace video
{
/// Gas leak detector class.
class GasLeakDetector : public VFilter
{
public:

    /// Constructor.
    GasLeakDetector();

    /// Destructor.
    ~GasLeakDetector();

    /// Get string of current library version.
    static std::string getVersion();

    /// Initialize detector.
    bool initVFilter(VFilterParams& params) override;
    
    /// Set detector parameter.
    bool setParam(VFilterParam id, float value) override;

    /// Get detector parameter value.
    float getParam(VFilterParam id) override;

    /// Get all detector parameters.
    void getParams(VFilterParams& params) override;

    /// Execute action command.
    bool executeCommand(VFilterCommand id) override;

    /// Process frame.
    bool processFrame(cr::video::Frame& frame) override;
    
    /// Set detector mask.
    bool setMask(cr::video::Frame mask) override;

    /// Decode and execute command.
    bool decodeAndExecuteCommand(uint8_t* data, int size) override;
};
}
}

getVersion method

The getVersion() method returns string of current version of GasLeakDetector class. Method declaration:

static std::string getVersion();

Method can be used without GasLeakDetector class instance. Example:

cout << "GasLeakDetector v: " << GasLeakDetector::getVersion();

Console output:

GasLeakDetector v: 1.0.0

initVFilter method

The initVFilter(…) method initializes GasLeakDetector class by VFilterParams object which includes all video filter parameters. Method declaration:

bool initVFilter(VFilterParams& params) override;

Parameter	Value
params	VFilterParams class object. The library uses only mode and level parameters.

Returns: TRUE if the video filter initialized or FALSE if not.

setParam method

The setParam(…) method designed to set new GasLeakDetector object parameter value. setParam(…) is thread-safe method. This means that the setParam(…) method can be safely called from any thread. Method declaration:

bool setParam(VFilterParam id, float value) override;

Parameter	Description
id	Parameter ID according to VFilterParam enum.
value	Parameter value. Value depends on parameter ID.

Returns: TRUE if the parameter was set or FALSE if not.

getParam method

The getParam(…) method designed to obtain library parameter value. getParam(…) is thread-safe method. This means that the getParam(…) method can be safely called from any thread. Method declaration:

float getParam(VFilterParams id) override;

Parameter	Description
id	Parameter ID according to VFilterParam enum.

Returns: parameter value or -1 if the parameter is not supported.

executeCommand method

The executeCommand(…) method designed to execute library command. executeCommand(…) is thread-safe method. This means that the executeCommand(…) method can be safely called from any thread. Method declaration:

bool executeCommand(VFilterCommand  id) override;

Parameter	Description
id	Command ID according to VFilterCommand enum.

Returns: TRUE if the command was executed or FALSE if not.

processFrame method

The processFrame(…) method designed to perform magnification algorithm. The library provides thread-safe processFrame(…) method call. This means that the processFrame(…) method can be safely called from any thread. Method declaration:

bool processFrame(cr::video::Frame& frame) override;

Parameter	Description
frame	Video Frame object for processing. Filter processes only GRAY, YUV24, YUYV, UYVY, NV12, NV21, YV12, YU12 formats. The library uses pixels intensity for video processing. If the pixel format of the image doesn’t include intensity channel it should be converted to proper format before applying filter.

Returns: TRUE if the video frame was processed FALSE if not. If filter is disabled the method should return TRUE.

setMask method

The setMask(…) method designed to set filter mask. The user can disable magnification in any areas of the video frame. For this purpose the user can create an image of any size and configuration with GRAY (preferable), NV12, NV21, YV12 or YU12 pixel format. Mask image pixel values equal to 0 prohibit magnification in the corresponding place of video frames. Any other mask pixel value other than 0 allows magnification at the corresponding location of video frames. The mask is used for magnification algorithms to compute a binary motion mask. The method can be called either before video frame processing or during video frame processing. Method declaration:

bool setMask(cr::video::Frame mask) override;

Parameter	Description
mask	Image of magnification mask (Frame object). Must have GRAY (preferable), NV12, NV21, YV12 or YU12 pixel format. The size and configuration of the mask image can be any. If the size of the mask image differs from the size of processed frames, the mask will be scaled by the library for processing.

Returns: TRUE if the the mask accepted or FALSE if not (not valid pixel format or empty).

encodeSetParamCommand method of VFilter class

The encodeSetParamCommand(…) static method encodes command to change any VFilter parameter value remote. To control any video filter remotely, the developer has to design his own protocol and according to it encode the command and deliver it over the communication channel. To simplify this, the VFilter class contains static methods for encoding the control command. The VFilter class provides two types of commands: a parameter change command (SET_PARAM) and an action command (COMMAND). encodeSetParamCommand(…) designed to encode SET_PARAM command. Method declaration:

static void encodeSetParamCommand(uint8_t* data, int& size, VFilterParam id, float value);

Parameter	Description
data	Pointer to data buffer for encoded command. Must have size >= 11.
size	Size of encoded data. Size will be 11 bytes.
id	Parameter ID according to VFilterParam enum.
value	Parameter value.

encodeSetParamCommand(…) is static and can be used without VFilter class instance. This method used on client side (control system). Command encoding example:

// Buffer for encoded data.
uint8_t data[11];
// Size of encoded data.
int size = 0;
// Random parameter value.
float outValue = static_cast<float>(rand() % 20);
// Encode command.
VFilter::encodeSetParamCommand(data, size, VFilterParam::LEVEL, outValue);

encodeCommand method of VFilter class

The encodeCommand(…) static method encodes action command for VFilter remote control. To control any video filter remotely, the developer has to design his own protocol and according to it encode the command and deliver it over the communication channel. To simplify this, the VFilter class contains static methods for encoding the control command. The VFilter class provides two types of commands: a parameter change command (SET_PARAM) and an action command (COMMAND). encodeCommand(…) designed to encode COMMAND (action command). Method declaration:

static void encodeCommand(uint8_t* data, int& size, VFilterCommand id);

Parameter	Description
data	Pointer to data buffer for encoded command. Must have size >= 7.
size	Size of encoded data. Size will be 7 bytes.
id	Command ID according to VFilterCommand enum.

encodeCommand(…) is static and can be used without VFilter class instance. This method used on client side (control system). Command encoding example:

// Buffer for encoded data.
uint8_t data[7];
// Size of encoded data.
int size = 0;
// Encode command.
VFilter::encodeCommand(data, size, VFilterCommand::RESTART);

decodeCommand method of VFilter class

The decodeCommand(…) static method decodes command on video filter side (on edge device). Method declaration:

static int decodeCommand(uint8_t* data, int size, VFilterParam& paramId, VFilterCommand& commandId, float& value);

Parameter	Description
data	Pointer to input command.
size	Size of command. Must be 11 bytes for SET_PARAM and 7 bytes for COMMAND (action command).
paramId	VFilter parameter ID according to VFilterParam enum. After decoding SET_PARAM command the method will return parameter ID.
commandId	VFilter command ID according to VFilterCommand enum. After decoding COMMAND the method will return command ID.
value	VFilter parameter value (after decoding SET_PARAM command).

Returns: 0 - in case decoding COMMAND (action command), 1 - in case decoding SET_PARAM command or -1 in case errors.

decodeAndExecuteCommand method

The decodeAndExecuteCommand(…) method decodes and executes command encoded by encodeSetParamCommand(…) and encodeCommand(…) methods on video filter side. The library provides thread-safe decodeAndExecuteCommand(…) method call. This means that the decodeAndExecuteCommand(…) method can be safely called from any thread. Method declaration:

bool decodeAndExecuteCommand(uint8_t* data, int size) override;

Parameter	Description
data	Pointer to input command.
size	Size of command. Must be 11 bytes for SET_PARAM or 7 bytes for COMMAND.

Returns: TRUE if command decoded (SET_PARAM or COMMAND) and executed (action command or set param command).

Data structures

VFilterCommand enum

Enum declaration:

enum class VFilterCommand
{
    /// Reset video filter algorithm.
    RESET = 1,
    /// Enable filter.
    ON,
    /// Disable filter.
    OFF
};

Table 2 - Action commands description.

Command	Description
RESET	Reset filter.
ON	Enable filter.
OFF	Disable filter. If OFF command is called, the library will reset algorithm at first.

VFilterParam enum

Enum declaration:

enum class VFilterParam
{
	/// Filter mode: 0 - off, 1 - on. Depends on implementation.
	MODE = 1,
	/// Enhancement level for particular filter, as a percentage from 
	/// 0% to 100%. May have another meaning depends on implementation.
	LEVEL,
	/// Processing time in microseconds. Read only parameter.
	PROCESSING_TIME_MCSEC,
	/// Type of the filter. Depends on the implementation.
	TYPE,
	/// VFilter custom parameter. Custom parameters used when particular image 
	/// filter has specific unusual parameter.
	CUSTOM_1,
	/// VFilter custom parameter. Custom parameters used when particular image 
	/// filter has specific unusual parameter.
	CUSTOM_2,
	/// VFilter custom parameter. Custom parameters used when particular image 
	/// filter has specific unusual parameter.
	CUSTOM_3
};

Table 3 - Params description.

Parameter	Access	Description
MODE	read / write	Mode. Default: 0 - Off, 1 - On. If the magnificator is not activated, frame processing is not performed, it will be only forwarded.
LEVEL	read / write	Amplification factor adjusts the intensity of motion enhancement in videos, with higher values emphasizing motion changes and lower values maintaining the original motion characteristics. Supported values are from 0 to 100%.
PROCESSING_TIME_MCSEC	read only	Processing time in microseconds. Read only parameter. Used to check performance of GasLeakDetector and shows processing time for last frame.
TYPE	read / write	Not supported by GasLeakDetector library.
CUSTOM_1	read / write	Not supported by GasLeakDetector library.
CUSTOM_2	read / write	Not supported by GasLeakDetector library.
CUSTOM_3	read / write	Not supported by GasLeakDetector library.

VFilterParams class description

VFilterParams class declaration

VFilterParams class is used to provide video filter parameters structure. Also VFilterParams provides possibility to write/read params from JSON files (JSON_READABLE macro) and provides methods to encode and decode params. VFilterParams interface class declared in VFilter.h file. Class declaration:

namespace cr
{
namespace video
{
/// VFilter parameters class.
class VFilterParams
{
public:

    /// Filter mode: 0 - off, 1 - on. Depends on implementation.
    int mode{ 1 };
    /// Enhancement level for particular filter, as a percentage from 
    /// 0% to 100%. May have another meaning depends on implementation.
    float level{ 0.0f };
    /// Processing time in microseconds. Read only parameter.
    int processingTimeMcSec{ 0 };
    /// Type of the filter. Depends on the implementation.
    int type{ 0 };
    /// VFilter custom parameter. Custom parameters used when particular image 
    /// filter has specific unusual parameter.
    float custom1{ 0.0f };
    /// VFilter custom parameter. Custom parameters used when particular image 
    /// filter has specific unusual parameter.
    float custom2{ 0.0f };
    /// VFilter custom parameter. Custom parameters used when particular image 
    /// filter has specific unusual parameter.
    float custom3{ 0.0f };

    /// Macro from ConfigReader to make params readable / writable from JSON.
    JSON_READABLE(VFilterParams, mode, level, type, custom1, custom2, custom3)

    /// operator =
    VFilterParams& operator= (const VFilterParams& src);

    /// Encode (serialize) params.
    bool encode(uint8_t* data, int bufferSize, int& size,
                VFilterParamsMask* mask = nullptr);

    /// Decode (deserialize) params.
    bool decode(uint8_t* data, int dataSize);
};
}
}

Table 5 - VFilterParams class fields description is related to VFilterParam enum description.

Field	type	Description
mode	int	Mode. Default: 0 - Off, 1 - On. If the library is not activated, frame processing is not performed, it will be only forwarded.
level	float	Amplification factor adjusts the intensity of motion enhancement in videos, with higher values emphasizing motion changes and lower values maintaining the original motion characteristics. Supported values are from 0 to 100%.
processingTimeMcSec	int	Processing time in microseconds. Read only parameter. Used to check performance of GasLeakDetector and shows processing time for last frame.
type	int	Not supported by GasLeakDetector library.
custom1	float	Not supported by GasLeakDetector library.
custom2	float	Not supported by GasLeakDetector library.
custom3	float	Not supported by GasLeakDetector library.

None: VFilterParams class fields listed in Table 5 have to reflect params set/get by methods setParam(…) and getParam(…).

Serialize VFilter params

VFilterParams class provides method encode(…) to serialize VFilter params. Serialization of VFilterParams is necessary in case when video filter parameters have to be sent via communication channels. Method provides options to exclude particular parameters from serialization. To do this method inserts binary mask (1 byte) where each bit represents particular parameter and decode(…) method recognizes it. Method declaration:

bool encode(uint8_t* data, int bufferSize, int& size, VFilterParamsMask* mask = nullptr);

Parameter	Value
data	Pointer to data buffer. Buffer size must be >= 32 bytes.
bufferSize	Data buffer size. Buffer size must be >= 32 bytes.
size	Size of encoded data.
mask	Parameters mask - pointer to VFilterParamsMask structure. VFilterParamsMask (declared in VFilter.h file) determines flags for each field (parameter) declared in VFilterParams class. If user wants to exclude any parameters from serialization, he can put a pointer to the mask. If the user wants to exclude a particular parameter from serialization, he should set the corresponding flag in the VFilterParamsMask structure.

Returns: TRUE if params encoded (serialized) or FALSE if not (buffer size < 32).

VFilterParamsMask structure declaration:

struct VFilterParamsMask
{
    bool mode{ true };
    bool level{ true };
    bool processingTimeMcSec{ true };
    bool type{ true };
    bool custom1{ true };
    bool custom2{ true };
    bool custom3{ true };
};

Example without parameters mask:

// Prepare parameters.
cr::video::VFilterParams params;
params.level = 80.0f;

// Encode (serialize) params.
int bufferSize = 128;
uint8_t buffer[128];
int size = 0;
params.encode(buffer, bufferSize, size);

Example with parameters mask:

// Prepare parameters.
cr::video::VFilterParams params;
params.level = 80.0;

// Prepare mask.
cr::video::VFilterParams mask;
// Exclude level.
mask.level = false;

// Encode (serialize) params.
int bufferSize = 128;
uint8_t buffer[128];
int size = 0;
params1.encode(buffer, bufferSize, size, &mask);

Deserialize VFilter params

VFilterParams class provides method decode(…) to deserialize params. Deserialization of VFilterParams is necessary in case when it is needed to receive params via communication channels. Method automatically recognizes which parameters were serialized by encode(…) method. Method declaration:

bool decode(uint8_t* data, int dataSize);

Parameter	Value
data	Pointer to data buffer with serialized params.
dataSize	Size of command data.

Returns: TRUE if params decoded (deserialized) or FALSE if not.

Example:

// Prepare parameters.
cr::video::VFilterParams params1;
params1.level = 80;

// Encode (serialize) params.
int bufferSize = 128;
uint8_t buffer[128];
int size = 0;
params1.encode(buffer, bufferSize, size);

// Decode (deserialize) params.
cr::video::VFilterParams params2;
params2.decode(buffer, size);

Read params from JSON file and write to JSON file

VFilter depends on open source ConfigReader library which provides method to read params from JSON file and to write params to JSON file. Example of writing and reading params to JSON file:

// Prepare random params.
cr::video::VFilterParams params1;
params1.mode = 1;
params1.level = 10.1f;
params1.processingTimeMcSec = 10;
params1.type = 2;
params1.custom1 = 22.3;
params1.custom2 = 23.4;
params1.custom3 = 24.5;

// Save to JSON.
cr::utils::ConfigReader configReader1;
if (!configReader1.set(params1, "Params"))
    std::cout << "Can't set params" << std::endl;
if (!configReader1.writeToFile("VFilterParams.json"))
    std::cout << "Can't write to file" << std::endl;

// Read params from file.
cr::utils::ConfigReader configReader2;
if (!configReader2.readFromFile("VFilterParams.json"))
    std::cout << "Can't read from file" << std::endl;
cr::video::VFilterParams params2;
if (!configReader2.get(params2, "Params"))
    std::cout << "Can't get params" << std::endl;

VFilterParams.json will look like:

{
    "Params": {
        "custom1": 22.3,
        "custom2": 23.4,
        "custom3": 24.5,
        "level": 10.1,
        "mode": 1,
        "type": 2
    }
}

Build and connect to your project

Before built user has to install OpenCV library. Example for Linux Ubuntu:

sudo apt install libopencv-dev

Typical commands to build GasLeakDetector library:

cd GasLeakDetector
mkdir build
cd build
cmake ..
make

If you want connect GasLeakDetector to your CMake project as source code you can make follow. For example, if your repository has structure:

CMakeLists.txt
src
    CMakeList.txt
    yourLib.h
    yourLib.cpp

Create folder 3rdparty in your repository and copy GasLeakDetector repository folder there. New structure of your repository:

CMakeLists.txt
src
    CMakeList.txt
    yourLib.h
    yourLib.cpp
3rdparty
    GasLeakDetector

Create CMakeLists.txt file in 3rdparty folder. CMakeLists.txt should contain:

cmake_minimum_required(VERSION 3.13)

################################################################################
## 3RD-PARTY
## dependencies for the project
################################################################################
project(3rdparty LANGUAGES CXX)

################################################################################
## SETTINGS
## basic 3rd-party settings before use
################################################################################
# To inherit the top-level architecture when the project is used as a submodule.
SET(PARENT ${PARENT}_YOUR_PROJECT_3RDPARTY)
# Disable self-overwriting of parameters inside included subdirectories.
SET(${PARENT}_SUBMODULE_CACHE_OVERWRITE OFF CACHE BOOL "" FORCE)

################################################################################
## INCLUDING SUBDIRECTORIES
## Adding subdirectories according to the 3rd-party configuration
################################################################################
add_subdirectory(GasLeakDetector)

File 3rdparty/CMakeLists.txt adds folder GasLeakDetector (by default test applications and example excluded from compiling if GasLeakDetector included as sub-repository). The new structure of your repository will be:

CMakeLists.txt
src
    CMakeList.txt
    yourLib.h
    yourLib.cpp
3rdparty
    CMakeLists.txt
    GasLeakDetector

Next, you need to include the 3rdparty folder in the main CMakeLists.txt file of your repository. Add the following string at the end of your main CMakeLists.txt:

add_subdirectory(3rdparty)

Next, you have to include GasLeakDetector library in your src/CMakeLists.txt file:

target_link_libraries(${PROJECT_NAME} GasLeakDetector)

Done!

Example

A simple application shows how to use the GasLeakDetector library. The application opens a video file “test.mp4”.

#include <opencv2/opencv.hpp>
#include "GasLeakDetector.h"

int main(void)
{
    // Open video file "test.mp4".
    cv::VideoCapture videoSource;
    if (!videoSource.open("test.mp4"))
        return -1;

    // Create frames.
    cv::Mat bgrImg;
    int width = (int)videoSource.get(cv::CAP_PROP_FRAME_WIDTH);
    int height = (int)videoSource.get(cv::CAP_PROP_FRAME_HEIGHT);
    cr::video::Frame frameYuv(width, height, cr::video::Fourcc::YUV24);

    // Create gas leak detector and set initial params.
    cr::video::GasLeakDetector filter;
    filter.setParam(cr::video::VFilterParam::MODE, 1); // Enable.
    filter.setParam(cr::video::VFilterParam::LEVEL, 50); // 50% level.

    // Main loop.
    while (true)
    {
        // Capture next video frame. Default BGR pixel format.
        videoSource >> bgrImg;
        if (bgrImg.empty())
        {
            // Set initial video position to replay.
            videoSource.set(cv::CAP_PROP_POS_FRAMES, 0);
            continue;
        }

        // Convert BGR to YUV for filter.
        cv::Mat yuvImg(height, width, CV_8UC3, frameYuv.data);
        cv::cvtColor(bgrImg, yuvImg, cv::COLOR_BGR2YUV);

        // Magnify movement with default params.
        filter.processFrame(frameYuv);

        // Convert result YUV to BGR to display.
        cv::cvtColor(yuvImg, bgrImg, cv::COLOR_YUV2BGR);

        // Show video.
        cv::imshow("VIDEO", bgrImg);
        if (cv::waitKey(1) == 27)
            return 0;
    }
    return 1;
}

Benchmark

Benchmark allows you to evaluate the speed of the algorithm on different platforms. This is a console application that allows you to enter initial parameters after startup. After entering the parameters, the application will create 100 synthetic images and process them. After processing 100 images, the application will calculate and show statistics (average / minimum / maximum processing time per frame). Benchmark console interface:

=================================================
GasLeakDetector v1.0.0 benchmark
Average processing time per frame
=================================================

Set frame width: 1920
Set frame height: 1080
Time 6.576 -> 7.337 -> 9.47 msec
Time 6.556 -> 7.391 -> 12.945 msec
Time 6.669 -> 7.586 -> 12.512 msec
Time 6.716 -> 7.72 -> 13.716 msec

Demo application

The demo application is intended to evaluate the performance of the GasLeakDetector C++ library. The application allows you to evaluate the magnification algorithm with chosen video file. It is a console application and can be used as an example of GasLeakDetector library usage. The application uses the OpenCV (version 4.5 and higher) library for capturing video, recording video, displaying video, and forming a simple user interface. The demo application does not require installation. The demo application compiled for Windows OS x64 (Windows 10 and never) as well for Linux OS (few distros, to get demo application for specific Linux distro sent us request). Table 6. shows list of files of demo application.

Table 6 - List of files of demo application (example for Windows OS).

File	Description
GasLeakDetectorDemo.exe	Demo application executable file for windows OS.
opencv_world480.dll	OpenCV library file version 4.8.0 for Windows x64.
opencv_videoio_msmf480_64.dll	OpenCV library file version 4.8.0 for Windows x64.
opencv_videoio_ffmpeg480_64.dll	OpenCV library file version 4.8.0 for Windows x64.
VC_redist.x64	Installer of necessary system libraries for Windows x64.
src	Folder with application source code.
test.mp4	Test video file.

To launch demo application run GasLeakDetectorDemo.exe executable file on Windows x64 OS or run commands on Linux:

sudo chmod +x GasLeakDetectorDemo
./GasLeakDetectorDemo

If a message about missing system libraries appears (on Windows OS) when launching the application, you must install the VC_redist.x64.exe program, which will install the system libraries required for operation. After start user must chose platform:

=================================================
GasLeakDetector v1.0.0 demo application
=================================================

Open file dialog? (y/n) y

After user should chose between file dialog and initialization string (for OpenCV). If user will not chose file dialog option the application will ask to enter video source initialization string: user can manually set file name, camera number (0, 1, 2 etc.) or RTSP initialization string (example: rtsp://192.168.0.1:7031/live). After that the user will see the user interface as shown bellow (if video source open and region of interest is set).

To control the application, it is necessary that the main video display window was active (in focus), and also it is necessary that the English keyboard layout was activated without CapsLock mode. The program is controlled by the keyboard and mouse (magnification ROI control).

Table 7 - Control buttons.

Button	Description
ESC	Exit the application. If video recording is active, it will be stopped.
SPACE	Reset filter.
R	Start/stop video recording. When video recording is enabled, a files dst_[date and time].avi (result video) is created in the directory with the application executable file. Recording is performed of what is displayed to the user. To stop the recording, press the R key again. During video recording, the application shows a warning message.
E	Enable/disable filter.

Magnification level can be changed by slider. The user can set the magnification mask (mark a rectangular area where image will be magnified). In order to set a rectangular magnification area it is necessary to draw a line with the mouse with the left button pressed from the left-top corner of the required magnification area to the right-bottom corner. The magnification area will be marked in blue color as shown in the image.

---

Table of contents