逆向工程：从apk中提取图像/精灵表

I'm learning about game development and I'm trying to extract some resources from some games that I love to play, I'm doing this just to learn more about sprites and resource organization. The problem is every game I extract the images come with some kind of problem, sometimes just doesn't open and other times I can open the image but I see just some pixels.I'm learning about game development and I'm try