Subtract one picture from the other

[MrMorgana]

How to subtract one picture from the other

Hi All!
I ask for you help, how to subtract one image from another. The situation is next: i want to make icons from various objects for a game, which have semi transparent parts (the objects ^^). So, i have have an image with only the background on it, and another one (same background) and on the background there is a certain object (for example: screenshot of a building with fire animation, but the fire is semi transparent, so you can see, what is behind the flames). What i want to achive is getting a picture of the object without the background, and the most important is, that the background should be removed from behind the flames too (not only to cut around the flames), so in the end, i can save the object to a png file with the semi transparent flames, to put this new image on a new background, and behind the flames is the new background is visible, not the old one. [it is like, if i would like to extract a watermark from a watermarked image, to save it, and use it on another image]
So, is it even possible? If it is, how to do it?

Thank you in advance for your help

 

[Ehelper]

u need to visit Photoshop effect: Text On Fire | E-helper.info

 

[MrMorgana]

lol. that is not what i was talking about, but cool site thanks.
btw, already found a way to do it (just needed to have a black background, and then remove black color from image, and got finally the semi transparent flames )