Hi, I have just the same problem and sadly know next to nothing about PHP :/
I the codeline in my image.php should be this one, am I right?
<?php if (($zpmin_finallink)=='colorbox') { ?><a>" title="<?php echo getBareImageTitle();?>"><?php printCustomSizedImage(getAnnotatedImageTitle(),550); ?></a><?php } ?>
How and where exactly do I have to add the "photo:true"? I am using the theme zpminimal v1.4.1a
Would be great if you could help me!