Cool what you can do with photoshop !

The following is an example of how to turn a photograph of someone into a pumpkin lamp version of them

But first read this excellent web page on making your own pumpkin carving patterns, the techniques here are inspired by that web page.

Walt's Pumpkin Carving Secrets

First find a picture of the "victim".

In this case Jeff, a friend of mine who grows giant pumpkins for a hobby (the pumpkin on the fork lift is one of his).
Crop the face and enlarge it to a suitable size for a pumpkin template (I used 8 x 10)

Enlarging it before starting work makes the final result smoother as your tracing is all done at the larger resolution. This image is very pixalated at this high a resolution, but this doesn't matter for the tracing we are going to do.
Then trace over all of the major outlines using a black pen in photoshop - we will only be using black and white (black = pumpkin, white = no pumpkin)

In theory you can get 4 colors with pumpkin carving by half carving some areas from the front or back but I haven't tried that (See Walt's page)
Now we have to decide what we are going to cut and what we are going to leave. We could either make the face standout from the background by silhouetting it or make the face light against a dark background.

Here we are going to make the face light against a dark background so we fill the background with black.

For a silhoette we would need to add a frame and then fill outside that with black. Any of photoshops shape drawing tools work but circular frames seem to be more traditional with pumpkins.
Next we are going to fill the hair and beard area in black along with the glasses

But first we must outline their edges in white or they will blend into the background
Now we use the paintpot tool to fill the hair, beard and glasses area with black
This would be an impossible pattern to carve as the hair area is now barely connected to any other material - so it will break off.

Remember all light areas are going to be cut away (including our white edge lines) - so any dark areas not connected to the background are going to be cut away with them.

Add some connecting structs to stabalize the hair and simarly widen the connecting part for the glasses and reinforce where the chin joins. Plus add a frame to the glasses to prevent them being in mid air

The viewer's brain will fill in the missings bits and complete the picture

Plus the ear area looks a bit empty - trace some additional lines from the underlying image to give some detail to this area.
Now select the white areas of the image and cut them to make them transparent
This is our basic template.
Finally a tidy up step, any fine lines aren't going to show up well, widen them to make them show up (and easier to carve)

In this image there don't seem to be any really thin areas other than the glasses and the ear. The frames of the glasses are reinforced a bit - the ear is left as is - it will be tricky to carve but shouldn't cause too much problem.
This is how our pumpkin pattern will look when it is illuminated
Finally we invert the image to give us the cutting template - select all black areas, fill the whole image with black and then delete the selected area.

As a last check fill the background with black using the paintbox tool.
The entire image should go black proving that there are no hanging areas.

Print this template on your printer and use it in the usual way to carve the pumpkin.

To print a template bigger than a sheet of paper, use the photoshop print with preview feature and drag the image in the preview to show the appropriate part of it and print it. (if you deliberately overlap the print outs they will be easier to align later).

Tape together the resulting multiple print outs to make one big template

Finally the finished product