Adjustment layer- curves.

Before

                                                                   After
                         
Using Photoshop, I changed the colours of the picture by using, new layer, new adjustment layer, and curves, I edited each of the colours red, green and blue by changing the shape of the curve. I decided to make the image slightly darker and also more blue, because I chose a picture of Loki, who is a Frost Giant, and blue connotes the colour of coldness and frost.