php - Laravel captcha image not working in production but dev is ok -

i'm using following package johntaa/laravel-captcha enable captcha input on site. works fine in dev environment. however, in prod can't find image (present blank).

code

//login page @if (session::has('show_captcha'))      <div class="form-group">         <label for="captcha">captcha</label>         <p>{{ html::image(captcha::img(), 'captcha image')  }}</p>         {{ form::text('captcha',null,array('class' => 'form-control', 'placeholder' => 'enter characters'))}}     </div> @endif   //html output snippet in dev <p><img src="http://localhost:8888/mysite/public/captcha?730518" alt="captcha image"></p>   //html output snippet in prod <p><img src="http://mysite/captcha?262091" alt="captcha image"></p> 

clicking on dev link yields result prod link errors to:

call undefined function johntaa\captcha\imagecreatefrompng()

file location:

../vendor/johntaa/captcha/src/johntaa/captcha/captcha.php 

more issue gd module isn't installed. phpinfo() check.

if isn't enabled do:

sudo apt-get install php5-gd

to install (on ubuntu).