Tone and colour reversal
You can mess around with the tone curve even more by dragging both ends to the bottom of the graph, clicking on the centre point to anchor it in place, then dragging two peaks upward to make an “M” shape. This mixes normal tones in a seemingly chaotic pattern with reversed complementary colours giving the image a strangely attractive psychedelic appearance.
The proportions of normal to reversed tones and the lightness and contrast of the image can be tweaked by altering the positions of the two peaks and the centre point. Dragging the two end points in towards the middle narrows the tonal range and turns what would normally be highlights and shadows black, for a more dramatic effect. Again, this is a technique that can't be performed in Photoshop Elements 8, but can be done in GIMP 2, Paint Shop Pro X2 and Adobe Photoshop.