$ npm install -g capturejs

Usage: capturejs [options]

Options:
  -u, --uri <value>                URI (required)
  -o, --output <value>             Output image file (required)
  -p, --ssl-protocol <value>       Sets the SSL protocol for secure connections (default is SSLv3) (sslv3|sslv2|tlsv1|any)
  -I, --ignore-ssl-errors          Ignores SSL errors (expired/self-signed certificate errors)
  -W, --web-security               Enables web security and forbids cross-domain XHR (default is true) (true|false|yes|no)
  -s, --selector <value>           CSS selector
  -A, --user-agent <value>         UserAgent
  -J, --javascript-file <value>    Inject external script code from the specified file into the page
  -j, --inject-script              Inject in-line custom scripts into the page
  -V, --viewportsize <value>       ViewPortSize {width}x{height}
  -C, --cliprect <value>           ClipRect {top}x{left}x{width}x{height} that will be rendered
  -c, --cookies-file <value>       Cookies file
  -T, --timeout <value>            HTTP Timeout (ms)
  -R, --renderdelay <value>        Render delay (ms)
  -w, --waitcapturedelay <value>   Capture delay (ms)
  -z, --zoomfactor <value>         Zoom Factor (default is 1.0, i.e. 100% zoom)

  -v, --version                    Show version number and exit
  -h, --help                       Show this message and exit

% capturejs --uri http://phantomjs.org/ \
            --selector '.header' \
            --viewportsize 1400x1400 \
            --output 'phantomjs.org.png'

% capturejs --uri http://phantomjs.org/ \
            --selector '.header' \
            --viewportsize 1400x1400 \
            --javascript-file ./hidelogo.js \
            --output 'phantomjs.org_hide_logo.png'

% capturejs --uri http://phantomjs.org/ \
            --selector '.header' \
            --viewportsize 1400x1400 \
            --javascript-file ./hidelogo.js \
            --inject-script 'document.querySelector(".header").style.background = 'red';' \
            --output 'phantomjs_org_red.png'