using make to convert images to thumbs

[Python]

I have a client that laid out their images and thumbs into almost
parallel directory structures.
	/img		/thumb
	  /x		  /img
	    /y		    /x
	      /*.jpg	      /y
			        /*.jpg

x and y are two digit directory names used to shorten the directory
scans to retrieve files.  I thought I could use a Makefile to automate
the creation of thumbs, but this pattern has me stumped.

I am going to just write a script to step through the source tree and
check the corresponding time stamp unless someone offers a suggestion.
(No they will not shuffle things around because they have lots of logic
in place.)

-- 
Lloyd Kvam
Venix Corp