[Lazarus] JPEG Dimensions

[ADTEC (Pty) Ltd]

Does anyone know of a simple way to determine the picture dimensions
for a JPEG file? I can determine them using the LazJPG unit and
loading the file into a variable. The problem is that when I'm trying
to determine the dimensions on a whole directory of files, the time
taken to load each file makes the process unuseable.

I've tried to understand the file layout for jpg files (wikipedia and
jpeg.org) but don't see where the final dimensions are stored. What I
would like to do is read just enough of each file to get the height
and width of the final image. Any suggestions?

Thanks

Graham Cooke