Looking for some Gallery-like Software

[Scout_II]

I have come to accept that either my Google-fu is weak...or it doesn't exist, but before I gave up on it entirely - I thought I would ask.

 

Basically I am looking for something that is capable of assembling size comparison photos on the fly.  I have posted a few examples of what kind of an end result I am going for.  Ideally, something that would allow a user to select two or more thumbnail images (say a Honda Civic and a M1A1 tank).  The software would then reference a database for the size of the vehicle and the pixels per foot or whatever of the object compared to the real version.  Once it had that - it would scale the images as needed and build a single output image.  Obviously the output would be determined by the input...but that is another matter all together.

 

http://www.loganotron.com/wp-content/uploads/2009/01/comparison.gif

 

http://upload.wikimedia.org/wikipedia/commons/f/f4/Tanker-size-comparison.png

 

http://onlyfunnyjokes.com/bestoftheweb/wp-uploads/earth_planets_size_comparison.jpg

 

It is sort of a niche application, so I wouldn't be surprised if nothing exists along those lines - however there are a lot of different things which utilize similar processes.  My problem in searching was figuring out what search terms would be more appropriate.  I know it is doable using GD - I just am about as rusty as you can get, so I was hoping to find something that is already there.