The 12 pictures clue the names of twelve quilt blocks in alphabetical order:
Follow the path of the mets, counting mets in each block from entry to exit. For instance, the path begins with seven mets in the Broken Dishes block, then four in Heart, then two in Bear's Paw, then three more in Heart, and so on. Note that the path passes through some blocks twice, producing different numbers.
Use each of these numbers as an index into the name of the corresponding block: the seventh letter of Broken Dishes, then the fourth of Heart, the second of Bear's Paw, the third of Heart, and so on. (If the path passes through a block twice, the block name is therefore used twice in this step.) These letters spell out DREAMCOAT WEARER, which is a thematic clue for JOSEPH, the answer to the puzzle.