Weird effects behavior

This is the effects example, that comes with C2:

<img src="http://i.imgur.com/ZVhYv.png" border="0" />

Now, I change the "C2 cog" image to anything. Here, I changed it to the cog that's already in C2 folder:

<img src="http://i.imgur.com/0POfE.png" border="0" />

Not a bug. Check the cog image provided in the example. It deliberately has lots of extra transparent space around it to show the effect more clearly. Both examples are working fine, but importing a different image with different areas of transparency won't look the same.

So my image needs extra transparent space around it, sufficient to fill the rest of the visible object behind it? This is strange, but it's good to know.