One of the many customizable options introduced with BlackBerry 10.2.1 was the ability to alter the white balance of your display. I'm not a user of this feature myself but I suspect many people will be and as we all know - options are always good.
Having the choice to alter the white balance may well also have some battery saving implications as the brighter and whiter the screen - the more juice your BlackBerry 10 smartphone will use.
With BlackBerry OS 10.2.1 we get a nice slider bar that at one end increases the balance to 'Cool White' and at the other to 'Warm White'. The 'cool' turns the white background to blue and the 'warm' to a yellow kind of sepia color. Depending on how far you slide the bar will depict how much the color changes.
Making the alterations is extremely straight forward:
Remember, you can also dim your screen brightness on this same settings page to save on battery.