Using Product Labels extension, it allows you to add label image for a bunch of products at the same time by using predefined conditions. You can create different conditions using product attributes and stock status. You can also select certain customer groups or date range for displaying product labels. When you edit a product, you can also select or upload image label for only that product. In Product Label tab, you can set 2 different images for category and product page. You can also set custom text and style for matching your design.