EDIT: Apparently this is called Solarization

So, I'm more a programmer than artist, but this is a cool (.. I like it) formula I developed for changing the value range of an image. The basic idea is you set a reflection point for min or max white light, lets say 127 min. All white light values greater (values where the min of R G and B is 127) go unaffected. All white light values less than this, have their value reflected (i.e. 120 is 7 below the line, so it's changed to be 7 above, or value = max(value, 127 + (127 - value)) .. sorry for the code stuff)

Anyways, it looks like this

notice how grey (127 value) is the max brightness in image 2, and the min brightness in image 3... this is different then level modding, as level modding would result in image 3 have an overly white suit. Unfortunately, max style inverts shading, which comes off a bit strange.

So, how to achieve it? Pretty simple, actually.

There are two layers to this. Create the two layers with layer "@vr" (value reflection) on top. Invert the color of "@vr" and then create an alpha layer mask. Paste a copy of the image in this layer mask. Desaturated (black and white) the mask (assuming white is full opacity) At this point you should have the min effect. If you want the max effect, invert the darkness of the mask. If you want to change the reflection point, change the brightness of the mask. Also try messing with the contrast.

P.S. this is my first post, so please be nice

P.P.S. This is only linear value reflection, and it leads to the common grey area (say.. ~100 to ~160) being doubled in color presence (into 127 to ~160). If you used rounded reflection (imagine the difference between a triangle and a dome), it would get even more grey heavy, but if you use inverse rounding (kind of a sombrero/pin tipped water drop shape), it would make it dart in and out of the gray range. To achieve this would require a special tool but you can get a sort of similar effect by adding contrast to everything.