Calculating size of an image in a container field

[Landy Atkinson]

I have just created an image database by importing a number of images 
into FMP8 from a series of folders.  During the import process, one 
can get the filename, file path, the image itself and a thumbnail of 
the image.

Now what I would like to do is create a calculating field that will 
tell me the image size (in KB) of the image in the container field 
(the one holding the JPEG, GIF or TIFF) image. Reading help and 
scanning the functions, I have not been able to figure out a way to 
achieve this.

Any suggestions?