c++ - Undefined symbol references in boost and CImg

I am new to using CImg and boost. I am getting undefined symbol references as mentioned below, in the code also shared below.

I am using this command line to build it: g++ -lboost_filesystem -lboost_system -L/usr/X11R6/lib -lm -lpthread -lX11 grayscaleConvertor.cpp &> errLog.txt

I am using the -l args in the compiler command. eg: -lboost_filesystem which I read on another post in stackoverflow, but that is not helping resolve the boost::filesystem:: symbols

locate CImg : /usr/include/CImg.h

locate boost: /usr/include/boost (plus more lines)

errLog.txt

/tmp/ccRIIPim.o: In function main':
grayscaleConvertor.cpp:(.text+0x179): undefined reference toboost::filesystem::path::extension() const'

grayscaleConvertor.cpp:(.text+0x213): undefined reference to boost::filesystem::path::filename() const'
/tmp/ccRIIPim.o: In function__static_initialization_and_destruction_0(int, int)':
grayscaleConvertor.cpp:(.text+0x68e): undefined reference to boost::system::generic_category()'
grayscaleConvertor.cpp:(.text+0x698): undefined reference toboost::system::generic_category()'
grayscaleConvertor.cpp:(.text+0x6a2): undefined reference to boost::system::system_category()'
/tmp/ccRIIPim.o: In functionboost::system::error_code::error_code()':
grayscaleConvertor.cpp:(.text._ZN5boost6system10error_codeC2Ev[_ZN5boost6system10error_codeC5Ev]+0x10): undefined reference to boost::system::system_category()'
/tmp/ccRIIPim.o: In functionboost::system::error_code::clear()':
grayscaleConvertor.cpp:(.text._ZN5boost6system10error_code5clearEv[_ZN5boost6system10error_code5clearEv]+0x10): undefined reference to boost::system::system_category()'
/tmp/ccRIIPim.o: In functionboost::filesystem::path::compare(std::__cxx11::basic_string, std::allocator > const&) const':

grayscaleConvertor.cpp:(.text._ZNK5boost10filesystem4path7compareERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE[_ZNK5boost10filesystem4path7compareERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE]+0x3b): undefined reference to boost::filesystem::path::compare(boost::filesystem::path const&) const'
/tmp/ccRIIPim.o: In functionboost::filesystem::exists(boost::filesystem::path const&)':
grayscaleConvertor.cpp:(.text._ZN5boost10filesystem6existsERKNS0_4pathE[_ZN5boost10filesystem6existsERKNS0_4pathE]+0x24): undefined reference to boost::filesystem::detail::status(boost::filesystem::path const&, boost::system::error_code*)'
/tmp/ccRIIPim.o: In functionboost::filesystem::is_directory(boost::filesystem::path const&)':
grayscaleConvertor.cpp:(.text._ZN5boost10filesystem12is_directoryERKNS0_4pathE[_ZN5boost10filesystem12is_directoryERKNS0_4pathE]+0x24): undefined reference to boost::filesystem::detail::status(boost::filesystem::path const&, boost::system::error_code*)'
/tmp/ccRIIPim.o: In functionboost::filesystem::is_regular_file(boost::filesystem::path const&)':
grayscaleConvertor.cpp:(.text._ZN5boost10filesystem15is_regular_fileERKNS0_4pathE[_ZN5boost10filesystem15is_regular_fileERKNS0_4pathE]+0x24): undefined reference to boost::filesystem::detail::status(boost::filesystem::path const&, boost::system::error_code*)'
/tmp/ccRIIPim.o: In functionboost::filesystem::directory_entry::status(boost::system::error_code&) const':
grayscaleConvertor.cpp:(.text._ZNK5boost10filesystem15directory_entry6statusERNS_6system10error_codeE[_ZNK5boost10filesystem15directory_entry6statusERNS_6system10error_codeE]+0x31): undefined reference to boost::filesystem::directory_entry::m_get_status(boost::system::error_code*) const'
/tmp/ccRIIPim.o: In functionboost::filesystem::directory_entry::symlink_status(boost::system::error_code&) const':

grayscaleConvertor.cpp:(.text._ZNK5boost10filesystem15directory_entry14symlink_statusERNS_6system10error_codeE[_ZNK5boost10filesystem15directory_entry14symlink_statusERNS_6system10error_codeE]+0x31): undefined reference to boost::filesystem::directory_entry::m_get_symlink_status(boost::system::error_code*) const'
/tmp/ccRIIPim.o: In functionboost::filesystem::detail::dir_itr_imp::~dir_itr_imp()':
grayscaleConvertor.cpp:(.text._ZN5boost10filesystem6detail11dir_itr_impD2Ev[_ZN5boost10filesystem6detail11dir_itr_impD5Ev]+0x2e): undefined reference to boost::filesystem::detail::dir_itr_close(void*&, void*&)'
/tmp/ccRIIPim.o: In functionboost::filesystem::directory_iterator::directory_iterator(boost::filesystem::path const&)':
grayscaleConvertor.cpp:(.text._ZN5boost10filesystem18directory_iteratorC2ERKNS0_4pathE[_ZN5boost10filesystem18directory_iteratorC5ERKNS0_4pathE]+0x4a): undefined reference to boost::filesystem::detail::directory_iterator_construct(boost::filesystem::directory_iterator&, boost::filesystem::path const&, boost::system::error_code*)'
/tmp/ccRIIPim.o: In functionboost::filesystem::directory_iterator::directory_iterator(boost::filesystem::path const&, boost::system::error_code&)':
grayscaleConvertor.cpp:(.text._ZN5boost10filesystem18directory_iteratorC2ERKNS0_4pathERNS_6system10error_codeE[_ZN5boost10filesystem18directory_iteratorC5ERKNS0_4pathERNS_6system10error_codeE]+0x4b): undefined reference to boost::filesystem::detail::directory_iterator_construct(boost::filesystem::directory_iterator&, boost::filesystem::path const&, boost::system::error_code*)'
/tmp/ccRIIPim.o: In functionboost::filesystem::directory_iterator::increment()':
grayscaleConvertor.cpp:(.text._ZN5boost10filesystem18directory_iterator9incrementEv[_ZN5boost10filesystem18directory_iterator9incrementEv]+0xf): undefined reference to boost::filesystem::detail::directory_iterator_increment(boost::filesystem::directory_iterator&, boost::system::error_code*)'
/tmp/ccRIIPim.o: In functioncimg_library::cimg::Mutex_info::trylock(unsigned int)':

grayscaleConvertor.cpp:(.text._ZN12cimg_library4cimg10Mutex_info7trylockEj[_ZN12cimg_library4cimg10Mutex_info7trylockEj]+0x1c): undefined reference to pthread_mutex_trylock'
/tmp/ccRIIPim.o: In functioncimg_library::CImgDisplay::screen_width()':
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay12screen_widthEv[_ZN12cimg_library11CImgDisplay12screen_widthEv]+0x26): undefined reference to XOpenDisplay'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay12screen_widthEv[_ZN12cimg_library11CImgDisplay12screen_widthEv]+0x96): undefined reference toXCloseDisplay'
/tmp/ccRIIPim.o: In function cimg_library::CImgDisplay::screen_height()':
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay13screen_heightEv[_ZN12cimg_library11CImgDisplay13screen_heightEv]+0x26): undefined reference toXOpenDisplay'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay13screen_heightEv[_ZN12cimg_library11CImgDisplay13screen_heightEv]+0x96): undefined reference to XCloseDisplay'
/tmp/ccRIIPim.o: In functioncimg_library::CImgDisplay::_handle_events(_XEvent const*)':
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay14_handle_eventsEPK7_XEvent[_ZN12cimg_library11CImgDisplay14_handle_eventsEPK7_XEvent]+0xb5): undefined reference to XUnmapWindow'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay14_handle_eventsEPK7_XEvent[_ZN12cimg_library11CImgDisplay14_handle_eventsEPK7_XEvent]+0x112): undefined reference toXCheckWindowEvent'

grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay14_handle_eventsEPK7_XEvent[_ZN12cimg_library11CImgDisplay14_handle_eventsEPK7_XEvent]+0x1f0): undefined reference to XResizeWindow'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay14_handle_eventsEPK7_XEvent[_ZN12cimg_library11CImgDisplay14_handle_eventsEPK7_XEvent]+0x2c2): undefined reference toXCheckWindowEvent'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay14_handle_eventsEPK7_XEvent[_ZN12cimg_library11CImgDisplay14_handle_eventsEPK7_XEvent]+0x317): undefined reference to XGetWindowAttributes'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay14_handle_eventsEPK7_XEvent[_ZN12cimg_library11CImgDisplay14_handle_eventsEPK7_XEvent]+0x335): undefined reference toXSync'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay14_handle_eventsEPK7_XEvent[_ZN12cimg_library11CImgDisplay14_handle_eventsEPK7_XEvent]+0x356): undefined reference to XSetInputFocus'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay14_handle_eventsEPK7_XEvent[_ZN12cimg_library11CImgDisplay14_handle_eventsEPK7_XEvent]+0x472): undefined reference toXCheckWindowEvent'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay14_handle_eventsEPK7_XEvent[_ZN12cimg_library11CImgDisplay14_handle_eventsEPK7_XEvent]+0x5c4): undefined reference to XCheckWindowEvent'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay14_handle_eventsEPK7_XEvent[_ZN12cimg_library11CImgDisplay14_handle_eventsEPK7_XEvent]+0x601): undefined reference toXLookupString'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay14_handle_eventsEPK7_XEvent[_ZN12cimg_library11CImgDisplay14_handle_eventsEPK7_XEvent]+0x635): undefined reference to XQueryKeymap'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay14_handle_eventsEPK7_XEvent[_ZN12cimg_library11CImgDisplay14_handle_eventsEPK7_XEvent]+0x6d8): undefined reference toXLookupString'

grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay14_handle_eventsEPK7_XEvent[_ZN12cimg_library11CImgDisplay14_handle_eventsEPK7_XEvent]+0x71b): undefined reference to XCheckWindowEvent'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay14_handle_eventsEPK7_XEvent[_ZN12cimg_library11CImgDisplay14_handle_eventsEPK7_XEvent]+0x7f0): undefined reference toXCheckWindowEvent'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay14_handle_eventsEPK7_XEvent[_ZN12cimg_library11CImgDisplay14_handle_eventsEPK7_XEvent]+0x861): undefined reference to XCheckWindowEvent'
/tmp/ccRIIPim.o: In functioncimg_library::CImgDisplay::_events_thread(void*)':
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay14_events_threadEPv[_ZN12cimg_library11CImgDisplay14_events_threadEPv]+0x6a): undefined reference to XCheckTypedEvent'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay14_events_threadEPv[_ZN12cimg_library11CImgDisplay14_events_threadEPv]+0x94): undefined reference toXCheckMaskEvent'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay14_events_threadEPv[_ZN12cimg_library11CImgDisplay14_events_threadEPv]+0x14c): undefined reference to pthread_testcancel'
/tmp/ccRIIPim.o: In functioncimg_library::CImgDisplay::_set_colormap(unsigned long&, unsigned int)':
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay13_set_colormapERmj[_ZN12cimg_library11CImgDisplay13_set_colormapERmj]+0x2a2): undefined reference to XStoreColors'
/tmp/ccRIIPim.o: In functioncimg_library::CImgDisplay::_map_window()':

grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay11_map_windowEv[_ZN12cimg_library11CImgDisplay11_map_windowEv]+0x50): undefined reference to XMapRaised'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay11_map_windowEv[_ZN12cimg_library11CImgDisplay11_map_windowEv]+0x74): undefined reference toXWindowEvent'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay11_map_windowEv[_ZN12cimg_library11CImgDisplay11_map_windowEv]+0xcb): undefined reference to XGetWindowAttributes'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay11_map_windowEv[_ZN12cimg_library11CImgDisplay11_map_windowEv]+0xe9): undefined reference toXSync'
/tmp/ccRIIPim.o: In function cimg_library::CImgDisplay::_paint(bool)':
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay6_paintEb[_ZN12cimg_library11CImgDisplay6_paintEb]+0xcd): undefined reference toXSendEvent'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay6_paintEb[_ZN12cimg_library11CImgDisplay6_paintEb]+0x130): undefined reference to XPutImage'
/tmp/ccRIIPim.o: In functioncimg_library::CImgDisplay::_init_fullscreen()':
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay16_init_fullscreenEv[_ZN12cimg_library11CImgDisplay16_init_fullscreenEv]+0xfe): undefined reference to XCreateWindow'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay16_init_fullscreenEv[_ZN12cimg_library11CImgDisplay16_init_fullscreenEv]+0x1df): undefined reference toXCreateImage'

grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay16_init_fullscreenEv[_ZN12cimg_library11CImgDisplay16_init_fullscreenEv]+0x208): undefined reference to XSelectInput'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay16_init_fullscreenEv[_ZN12cimg_library11CImgDisplay16_init_fullscreenEv]+0x226): undefined reference toXMapRaised'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay16_init_fullscreenEv[_ZN12cimg_library11CImgDisplay16_init_fullscreenEv]+0x24a): undefined reference to XWindowEvent'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay16_init_fullscreenEv[_ZN12cimg_library11CImgDisplay16_init_fullscreenEv]+0x2c1): undefined reference toXPutImage'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay16_init_fullscreenEv[_ZN12cimg_library11CImgDisplay16_init_fullscreenEv]+0x2e6): undefined reference to XGetWindowAttributes'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay16_init_fullscreenEv[_ZN12cimg_library11CImgDisplay16_init_fullscreenEv]+0x304): undefined reference toXSync'
/tmp/ccRIIPim.o: In function cimg_library::CImgDisplay::_desinit_fullscreen()':
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay19_desinit_fullscreenEv[_ZN12cimg_library11CImgDisplay19_desinit_fullscreenEv]+0x28): undefined reference toXUngrabKeyboard'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay19_desinit_fullscreenEv[_ZN12cimg_library11CImgDisplay19_desinit_fullscreenEv]+0x4d): undefined reference to XDestroyWindow'
/tmp/ccRIIPim.o: In functioncimg_library::CImgDisplay::_assign(unsigned int, unsigned int, char const*, unsigned int, bool, bool)':

grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb[_ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb]+0xf7): undefined reference to XOpenDisplay'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb[_ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb]+0x330): undefined reference toXVisualIDFromVisual'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb[_ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb]+0x34b): undefined reference to XGetVisualInfo'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb[_ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb]+0x392): undefined reference toXFree'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb[_ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb]+0x3d2): undefined reference to pthread_create'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb[_ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb]+0x57c): undefined reference toXCreateWindow'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb[_ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb]+0x5e3): undefined reference to XCreateSimpleWindow'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb[_ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb]+0x614): undefined reference toXSelectInput'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb[_ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb]+0x650): undefined reference to XStoreName'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb[_ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb]+0x6ab): undefined reference toXCreateColormap'

grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb[_ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb]+0x703): undefined reference to XSetWindowColormap'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb[_ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb]+0x70b): undefined reference toXAllocClassHint'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb[_ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb]+0x741): undefined reference to XSetClassHint'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb[_ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb]+0x74f): undefined reference toXFree'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb[_ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb]+0x84a): undefined reference to XCreateImage'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb[_ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb]+0x870): undefined reference toXInternAtom'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb[_ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb]+0x896): undefined reference to XInternAtom'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb[_ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb]+0x8ce): undefined reference toXSetWMProtocols'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb[_ZN12cimg_library11CImgDisplay7_assignEjjPKcjbb]+0x902): undefined reference to XGrabKeyboard'
/tmp/ccRIIPim.o: In functioncimg_library::CImgDisplay::assign()':

grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay6assignEv[_ZN12cimg_library11CImgDisplay6assignEv]+0x10c): undefined reference to XDestroyWindow'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay6assignEv[_ZN12cimg_library11CImgDisplay6assignEv]+0x17b): undefined reference toXFreeColormap'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay6assignEv[_ZN12cimg_library11CImgDisplay6assignEv]+0x198): undefined reference to XSync'
/tmp/ccRIIPim.o: In functioncimg_library::CImgDisplay::resize(int, int, bool)':
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay6resizeEiib[_ZN12cimg_library11CImgDisplay6resizeEiib]+0x208): undefined reference to XResizeWindow'
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay6resizeEiib[_ZN12cimg_library11CImgDisplay6resizeEiib]+0x227): undefined reference toXGetWindowAttributes'
/tmp/ccRIIPim.o: In function cimg_library::CImgDisplay::move(int, int)':
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay4moveEii[_ZN12cimg_library11CImgDisplay4moveEii]+0x72): undefined reference toXMoveWindow'
/tmp/ccRIIPim.o: In function void cimg_library::CImgDisplay::_resize(unsigned char, unsigned int, unsigned int, bool)':
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay7_resizeIhEEvT_jjb[_ZN12cimg_library11CImgDisplay7_resizeIhEEvT_jjb]+0x106): undefined reference toXCreateImage'

/tmp/ccRIIPim.o: In function void cimg_library::CImgDisplay::_resize(unsigned short, unsigned int, unsigned int, bool)':
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay7_resizeItEEvT_jjb[_ZN12cimg_library11CImgDisplay7_resizeItEEvT_jjb]+0x10b): undefined reference toXCreateImage'
/tmp/ccRIIPim.o: In function void cimg_library::CImgDisplay::_resize(unsigned int, unsigned int, unsigned int, bool)':
grayscaleConvertor.cpp:(.text._ZN12cimg_library11CImgDisplay7_resizeIjEEvT_jjb[_ZN12cimg_library11CImgDisplay7_resizeIjEEvT_jjb]+0x106): undefined reference toXCreateImage'
/tmp/ccRIIPim.o: In function boost::filesystem::path::path(boost::filesystem::directory_entry const&, boost::enable_if::type>, void>::type*)':
grayscaleConvertor.cpp:(.text._ZN5boost10filesystem4pathC2INS0_15directory_entryEEERKT_PNS_9enable_ifINS0_11path_traits11is_pathableINS_5decayIS4_E4typeEEEvE4typeE[_ZN5boost10filesystem4pathC5INS0_15directory_entryEEERKT_PNS_9enable_ifINS0_11path_traits11is_pathableINS_5decayIS4_E4typeEEEvE4typeE]+0x21): undefined reference toboost::filesystem::path_traits::dispatch(boost::filesystem::directory_entry const&, std::__cxx11::basic_string, std::allocator >&)'
collect2: error: ld returned 1 exit status

grayscaleConvertor.cpp

#define BOOST_FILESYSTEM_VERSION 3
#define BOOST_FILESYSTEM_NO_DEPRECATED 
#include 

#include "CImg.h"
#include  
#include 

using namespace cimg_library;

using namespace std;

namespace fs = ::boost::filesystem;

int main()
{
    const string ext = ".png";
    fs::path root("/Downloads/testdata1/");

    if(!fs::exists(root) || !fs::is_directory(root)) return -1;


    fs::recursive_directory_iterator it(root);
    fs::recursive_directory_iterator endit;

    while(it != endit)
    {
        if(fs::is_regular_file(*it) && it->path().extension()==ext)
        {
            CImg image(it->path().filename().string().c_str()),
                gray(image.width(), image.height(), 1, 1, 0),

                grayWeight(image.width(), image.height(), 1, 1, 0),
                imgR(image.width(), image.height(), 1, 3, 0),
                imgG(image.width(), image.height(), 1, 3, 0),
                imgB(image.width(), image.height(), 1, 3, 0);
        }
        ++it;
    }
    return 0;
}