Hi,
Cant quite find the solution for my problem - i am stuck with a huge directory of images and need the structure to match.   
There are 2 problems - first is the string at the end of file name -the colors - change from 3 character like red to longer colors like Navy or ltblue
Second, the middle string (after the first 3 number and . ) is usually 3 digit characters but sometimes it is a letter followed by 2 digits
Here is some examples of what i got 
106.755black.jpg  or
104.s56ltblue.jpg     or
258.866peri.jpg     or 
109.049khaki.jpg
I need it to be 
102c.755.black.jpg   or
104.s56.ltblue.jpg      or
258.866.peri.jpg      or 
109.049.khaki.jpg
Any ideas? 
thanks