From July 1 to August 31, you can participate in the Wikimedia Pages Wanting Photos challenge. The goal of the Wikimedia Pages Wanting Photo challenge is to increase the use of already uploaded images on the Wikimedia Commons repository and to add images to articles that lack a suitable illustration image.
This year, for the second time, you can also participate in the Czech round of the international challenge and add missing images to articles on the Czech Wikipedia. Please see the Wikimedia Pages Wanting Photos competition page for the rules of the challenge as well as lists of articles without images.