Solarization

Solarization is a term first used to describe over exposure. The visual effect of solarization is that it inverts the tonal range of the image to make a mono photograph that looks between a positive and a negative image. In the darkroom this is done by exposing a partially exposed image to white light before completing development. It can also be done digitally, heres how:

Technique 1:

First of all I made a copy of my background layer.

Then I went to Image>Adjustments>Black&White

Then I inverted the image.

Then I changed the blend mode to Difference.

This was my final result: 

Technique 2:

First of all I made a copy of my background layer

Then I went to Image>adjustments>black&white

Then I went to Filter>Stylize>Solarize

Then I inverted my image.

This was my final result.

Technique 3: 

First I made a copy of the background layer.

Then I went to Image>adjustments>Black&white

Then I used the Curves to make this upside down V

Then I inverted my image

This was my final result