the best way not to display sertain images is place them in a category and prevent that category from showing in "new images" section:
in index.php find:
WHERE i.image_active = 1
(note its a part of a line!)
add right after: AND i.cat_id NOT IN (xx,xx,xx) so the end result should looks like this:WHERE i.image_active = 1 AND i.cat_id NOT IN (xx,xx,xx)
replace xx with categories IDs which u dont want to show.