Changing the background colors of around 100 pictures

We run 13 online games, mostly dedicated to animals: [login to view URL] On each game, players can complete missions in order to reach a higher level (1, 2, 3...) in a given field, and therefore climb up the rankings. Attached, you can find the picture of level 1 for each kind of activity in each game (there are 9 kinds of activities in each game, and the game are represented by numbers, ranging from 1 to 19). We need to create similar pictures with simply a background colour change: the new pictures be displayed when the level of the user for this activity is 0. That is to say, when the user is new to the game, and hasn't begun these activities yet. The new background color has to be brighter than the background color of level 1 (the darker the background, the higher your level for this activity). All level 0 pictures must have this background color (likewise, you can notice that all level 1 pictures have the same background color). To help you choose the most appropriate color for each game, we've attached a screenshot of how it looks. The color you chose for each game must be relevant with respects to the other colors used in this game. For some activities, we also want the level 0 picture to be slightly different from the level 1 picture (for instance, 1 coin instead of 3): see "[login to view URL]" in each game's folder. This project is not urgent, you can take as much time as you with to deliver a great work :)