npm install opencv --save

npm install opencv --save
\
> opencv@4.0.0 install /home/ubuntu/node_modules/opencv
> node-pre-gyp install --fallback-to-build

Package opencv was not found in the pkg-config search path.
Perhaps you should add the directory containing `opencv.pc'
to the PKG_CONFIG_PATH environment variable
No package 'opencv' found
gyp: Call to 'pkg-config --cflags "opencv >= 2.3.1"' returned exit status 1. while trying to load binding.gyp
gyp ERR! configure error
gyp ERR! stack Error: `gyp` failed with exit code: 1
gyp ERR! stack     at ChildProcess.onCpExit (/home/ubuntu/.nvm/versions/node/v4.1.1/lib/node_modules/npm/node_modules/node-gyp/lib/configure.js:355:16)
gyp ERR! stack     at emitTwo (events.js:87:13)
gyp ERR! stack     at ChildProcess.emit (events.js:172:7)
gyp ERR! stack     at Process.ChildProcess._handle.onexit (internal/child_process.js:200:12)
gyp ERR! System Linux 4.2.0-c9
gyp ERR! command "/home/ubuntu/.nvm/versions/node/v4.1.1/bin/node" "/home/ubuntu/.nvm/versions/node/v4.1.1/lib/node_modules/npm/node_modules/node-gyp/bin/node-gyp.js" "configure" "--fallback-to-build" "--module=/home/ubuntu/node_modules/opencv/build/opencv/v4.0.0/Release/node-v46-linux-x64/opencv.node" "--module_name=opencv" "--module_path=/home/ubuntu/node_modules/opencv/build/opencv/v4.0.0/Release/node-v46-linux-x64"
gyp ERR! cwd /home/ubuntu/node_modules/opencv
gyp ERR! node -v v4.1.1
gyp ERR! node-gyp -v v3.0.3
gyp ERR! not ok
node-pre-gyp ERR! build error
node-pre-gyp ERR! stack Error: Failed to execute '/home/ubuntu/.nvm/versions/node/v4.1.1/bin/node /home/ubuntu/.nvm/versions/node/v4.1.1/lib/node_modules/npm/node_modules/node-gyp/bin/node-gyp.js configure --fallback-to-build --module=/home/ubuntu/node_modules/opencv/build/opencv/v4.0.0/Release/node-v46-linux-x64/opencv.node --module_name=opencv --module_path=/home/ubuntu/node_modules/opencv/build/opencv/v4.0.0/Release/node-v46-linux-x64' (1)
node-pre-gyp ERR! stack     at ChildProcess.<anonymous> (/home/ubuntu/node_modules/opencv/node_modules/node-pre-gyp/lib/util/compile.js:83:29)
node-pre-gyp ERR! stack     at emitTwo (events.js:87:13)
node-pre-gyp ERR! stack     at ChildProcess.emit (events.js:172:7)
node-pre-gyp ERR! stack     at maybeClose (internal/child_process.js:817:16)
node-pre-gyp ERR! stack     at Process.ChildProcess._handle.onexit (internal/child_process.js:211:5)
node-pre-gyp ERR! System Linux 4.2.0-c9
node-pre-gyp ERR! command "/home/ubuntu/.nvm/versions/node/v4.1.1/bin/node" "/home/ubuntu/node_modules/opencv/node_modules/.bin/node-pre-gyp" "install" "--fallback-to-build"
node-pre-gyp ERR! cwd /home/ubuntu/node_modules/opencv
node-pre-gyp ERR! node -v v4.1.1
node-pre-gyp ERR! node-pre-gyp -v v0.6.17
node-pre-gyp ERR! not ok
Failed to execute '/home/ubuntu/.nvm/versions/node/v4.1.1/bin/node /home/ubuntu/.nvm/versions/node/v4.1.1/lib/node_modules/npm/node_modules/node-gyp/bin/node-gyp.js configure --fallback-to-build --module=/home/ubuntu/node_modules/opencv/build/opencv/v4.0.0/Release/node-v46-linux-x64/opencv.node --module_name=opencv --module_path=/home/ubuntu/node_modules/opencv/build/opencv/v4.0.0/Release/node-v46-linux-x64' (1)
npm ERR! Linux 4.2.0-c9
npm ERR! argv "/home/ubuntu/.nvm/versions/node/v4.1.1/bin/node" "/home/ubuntu/.nvm/versions/node/v4.1.1/bin/npm" "install" "opencv" "--save"
npm ERR! node v4.1.1
npm ERR! npm  v2.14.4
npm ERR! code ELIFECYCLE

npm ERR! opencv@4.0.0 install: `node-pre-gyp install --fallback-to-build`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the opencv@4.0.0 install script 'node-pre-gyp install --fallback-to-build'.
npm ERR! This is most likely a problem with the opencv package,
npm ERR! not with npm itself.
npm ERR! Tell the author that this fails on your system:
npm ERR!     node-pre-gyp install --fallback-to-build
npm ERR! You can get their info via:
npm ERR!     npm owner ls opencv
npm ERR! There is likely additional logging output above.

npm ERR! Please include the following file with any support request:
npm ERR!     /home/ubuntu/npm-debug.log