Adjusting token selection area. Can it be done?

What i am trying to do is resize the selectable area of a token. I have a large image but a significant portion of it is transparent and i don't want to be able to select the transparent area. Anyone know if this is a thing that can be changed?

Images have to be rectangular (and on Roll20 and in many games they seem to work better if they are square). If you can draw a rectangle that includes all of the image and cuts out some of the transparent area, then you can crop it in an image editing software like Photoshop, Paint.Net, or GIMP.

I have already Cropped the image to be square, and the centre of the image site perfectly in the grid. Sorry, I probably should have been more specific in the original post, but the image i'm working with is animated so the transparent elements are consistently shifting. See image below:

I do not believe there is any method of click selecting a token based on the alpha channel. You can Send to Back, which should help hedge against accidental selection. Or you can move it to the map layer once placed. (I assume the animation continues—I don't mess around with a lot of animation.)

Animated images cannot change their size. Their smallest dimensions are the minimum dimensions that contain all elements of the animation. Think of it like a filmstrip in a movie, the projector and the lens need the film to be a constant size for it to run through the projector and work. So there's no way to do this. I do not use animated images in Roll20, but I do encounter a problem with large area of effect templates that I lay down on the grid that are in front of other tokens. Maybe this is the problem you trying to solve? If so, you can try using the Send to Back command from the right-click menu, or maybe sending them to the Map Layer, but I am not sure if animations work on the Map Layer or not.

Thanks for the replies and help guys. But yeah, it's looking like the only thing do do really is to send it to the back. "I do encounter a problem with large area of effect templates that I lay down on the grid that are in front of other tokens. Maybe this is the problem you trying to solve?" - Rabulias. Yeah, this is the problem. Unfortunately i's something that need to be on the token layer so i guess i will just have to make do for now.