Slight Wordpress script modification

This project is very simple. I have a custom wordpress template but it has a small problem. Whenever someone posts a photo to the website, the image is cut off if the dimensions go beyond a certain threshold, this would be 620x2400. I have modified this but I don't like that it is not dynamic enough, and content can still be cut off, also if i try to increase it anymore, the div class that the image is contained within will remain the same size, which again, i don't like. Your task is to modify the script so that when an image is posted, the image div tag will adjust itself accordingly to display the entire image without cutting any of it off. It's a simple enough task so it shouldn't take too long. Looking forward to hearing from people. All developers that work for me may be hired again