how to get category from post id

1get_the_category($post->ID)

1$post   = get_post( 123 ); // Where 123 is the ID
2$output =  apply_filters( 'the_content', $post->post_content );

1<section class="films-tabs pd-40" id="portfolio">
2
3  <?php $film_genres = get_terms('portfolio_cat'); // get all the genres ?>
4
5<div class="container">
6<div class="row">
7  <!-- Nav tabs -->
8  <ul class="nav nav-tabs nav-justified">
9    <?php foreach($film_genres as $film_genre) { ?>
10      <li>
11        <a href="#<?php echo $film_genre->slug ?>" data-toggle="tab"><?php echo $film_genre->name ?></a>
12      </li>
13    <?php } ?>
14  </ul>
15</div>
16</div>
17
18  <!-- Tab panes -->
19  <div class="tab-content">
20
21    <?php foreach($film_genres as $film_genre) { ?>
22
23      <div class="tab-pane" id="<?php echo $film_genre->slug ?>">
24        <?php 	
25        $args = array(
26          'post_type' => 'portfolio',
27          'showposts' => -1,
28          'orderby' => 'title',
29          'order' => 'ASC',
30          'tax_query' => array(
31            array(
32              'taxonomy' => 'portfolio_cat',
33              'field' => 'slug',
34              'terms' => $film_genre->slug
35            )
36          )
37        );
38        $films = new WP_Query( $args );		
39        ?>
40
41        <?php if ( $films->have_posts() ) : // make sure we have films to show before doing anything?>
42        <div class="table">
43            <div class="container">
44                <div class="row">
45                  <?php while ( $films->have_posts() ) : $films->the_post(); ?>	
46                  
47                    <div class="table-cont"><a data-fancybox="gallery" href="<?php echo get_the_post_thumbnail_url();?>".><?php the_post_thumbnail() ?></a></div>
48                  
49                  <?php endwhile; ?>
50                  <?php wp_reset_query() ?>
51                 </div>
52            </div>
53        </div>
54        <?php endif; ?>
55
56      </div>
57    <? }  ?>
58
59  </div><!-- tab-content -->
60
61</section><!-- film-tabs -->