This is how I added captions, or cutlines, to the Articles content type in Openpublish. I hope that it is helpful to anyone who, like me, spent untold hours trying to figure it out.
First, add a field to the Article content type (../admin/content/node-type/article/fields). I labelled mine Caption and gave it the name field_main_image_caption. I chose Text for the field type and gave it a textfield size of 200.
Next, add something like: $vars['main_image_caption'] = $vars['field_main_image_caption'][0]['view'];
to node-article.tpl.inc below the // Main_image notation. (Here, I think I was a bad boy and changed the file in sites/all/modules/openpublish_core/theme_helpers because I was not sure if the override would work if I put my new version of the .inc file in my subtheme folder. I'll get around to looking at this at some point.)
Then it was time to edit my subtheme's node-article.tpl.php to display the caption. All I did was add <?php print $main_image_caption; ?> to the following:
if ($main_image): ?>
<div class="main-image">
<?php print $main_image; ?>
<div class="main-image-desc image-desc">
<?php print $main_image_caption; ?>
<span class="main-image-credit image-credit"><?php print $main_image_credit; ?></span>
</div><!-- /.main-image-desc -->
</div><!-- /.main-image -->
<?php endif; ?>After that, I added a caption to an article and changed my CSS for image-desc in components.css to something I liked.
That's it. Please let me know if I have written anything crazy that needs to be corrected, and I will edit the instructions.