Example

Some of the fireworks from the NC State Fair.

Okay, so it's not an x-ray image or anything like that, but it looks cool.  It's actually just a photo of a leaf.  I increased the brightness and contrast, changed the levels and curves, and inverted the color values.  Nothing special, but it looks neat.  I guess it would be like a density map of the leaf, if anything.

This was part of one of the displays at last year's chili cook-off at the Farmers Market.

After a slight increase in contrast and brightness, I just used the oilify filter (Filters -> Artistic -> Oilify) in the Gimp.  I used a mask size of 30 and an exponent of 8 at full resolution, then scaled the image.

An "Artisitic" bee "Portrait."  In the Gimp, I adjusted the levels to cut off about 8% on each end.  Then I added a soft glow before scaling down.

Just a broken piece of glass beside the railroad track in Wake Forest.  If my memory is correct, Katy took this photo.

To put the focus more on the glass, I selected it using the Paths Tool () in the Gimp.  Some of the other select tools would work too, but I usually prefer the Paths Tool.  Then used Control - I (Select -> Invert works too) to select everything except the glass.  Next, I desaturated the selection (Colors -> Desaturate -> Luminosity) and faded the desaturation to 75% (Edit -> Fade Desaturation -> Opacity = 75% ; Mode = Replace).  That's it.  Just Control - Shift - S (or File -> Save As) to save it.