Did u see "Predator" movies? Did u want to learn how to make his thermal vision? Read this tutorial
1) open image, which u want to tune. i will use this one:
2) using lasso tool select character(s):
3) press control + c and control + v then
4) hide background layer by clicking "eye" icon:
5) hold down control and click on layer with character(s)
6) add Gradient Map (Layer>New Adjustment Layer>Gradient Map)
7) click black & white stripe and choose Spectrum preset (this one like rainbow):
8] press control + e
9) press control + u and move "Hue" bar at -140 (or experiment if colors are bad)
10) Add noise now (Filter>Noise>Add Noise):
10) now make background layer visible (by clicking eye again)
11) your image should looks similiar to this:
12) click on background layer and press ctrl + u
13) click Colorize and move bars on:
Hue: 240
Saturation: 100
Lightness: -50
14) Add Noise:
15) select character layer and add Guassian Blur (Filters>Blur>Guassian Blur):
16) u can add hands if u want:

(cutted out .png, ripped from game Aliens vs Predator 2)
Here is final effect:
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