I often like to alter the white balance of an image to achieve a certain look. My post about vignetting, of November 21, 2013 shows a before and after image of model Andrelica from a series of boudoir photographs. The original image is a mixture of light from the electronic flashes and tungsten room lights. The retouched image has a different color cast than the original.
Adobe's Photoshop Lightroom is where I always start post processing. If I find a white balance setting that I like, I write it down and use it for other images in the series. In this series, the white balance, or color temperature of the image (called "Temp" in Lightroom) was changed from "As Shot" (6150) to +5135, and the Tint was changed from +7 to +34. This gives a cool, purplish tint to the image reminiscent of light from a crepuscular sky pouring through the bedroom windows:
Andrelica at either dawn or dusk.
Another note about vignettes. I previously mentioned they can be done in a single Curves adjustment layer set to a layer blending mode of Multiply. This is how I usually do it. Here, I used a 100% opacity soft black brush to paint on the white layer mask, but only over the upper part of Andrelica, from the elbows up. I then painted of the lower part of Andrelica using a 50% opacity black brush to paint from her elbows to her knees. This directs the viewer's eye to the upper part of Andrelica, because it is lighter than the rest of her. This is precisely where we want the viewer's eye to go.