Image entity table should be initialized during update by core updater. Did you use core updater to update to version 1.6?
Anyway, here what you could do:
use core updater and check for database differences
in core updater settings, enable Developer mode. Then open Developer tab, and run 'Initialize codebase' process.
if nothing helps, you can manually add entries to db tables. Script:
INSERT INTO `tb_image_entity` (`id_image_entity`, `name`, `classname`) VALUES
(1, 'categories', 'Category'),
(2, 'categoriesthumb', 'Category'),
(3, 'manufacturers', 'Manufacturer'),
(4, 'products', 'Product'),
(5, 'scenes', 'Scene'),
(6, 'scenesthumb', 'Scene'),
(7, 'stores', 'Store'),
(8, 'suppliers', 'Supplier');
INSERT INTO `tb_image_entity_lang` (`id_image_entity`, `id_lang`, `display_name`) VALUES
(1, 1, 'Categories'),
(2, 1, 'Categories Thumbnails'),
(3, 1, 'Manufacturers'),
(4, 1, 'Products'),
(5, 1, 'Scenes'),
(6, 1, 'Scenes Thumbnails'),
(7, 1, 'Stores'),
(8, 1, 'Suppliers');
INSERT INTO `tb_image_entity_lang`(id_image_entity, id_lang, display_name)
SELECT iel.id_image_entity, l.id_lang, iel.display_name
FROM `tb_image_entity_lang` iel
JOIN `tb_lang` l
WHERE l.id_lang != 1;