When we take colour photos they sometimes have subtle colour casts that our eyes adjust to and see as correct, but if tweaked could deliver more natural result.
The colour cast is caused by the affect of colour temperature which changes throughout the day or when using different types of light source. Photos taken at sunrise, for example, may have an orange cast, while at twilight or cloudy midday things can have a blue hue. Photos taken in rooms illuminated by normal household light bulbs will look very orange too, while photos taken under fluorescent lighting can look strangely green.
Digital cameras have a white balance setting that can be set to automatic to determine what colour cast is being recorded and compensate by filtering out excess colour casts, but they don't always get it right. While a warm sunset colour palette should be embraced and maybe enhanced, being able to digitally correct the colours in a photo taken in artificial light can be a godsend.
White Balance In Lightroom
In Adobe Lightroom there are three main methods to correct the colour balance so you end up with a neutral colour balanced photo.
Find The Develop Tab
View a photo in Lightroom and select the Develop tab.
WB (White Balance) Panel
In the Basic menu on the right you will see a WB (white balance) panel with an eye dropper icon, Temp and Tint sliders and a drop down menu, set to As Shot.
The drop down menu is the quick and easy auto approach to colour correction. As Shot is what the camera recorded. This may be one of the camera's presets or its Auto White balance (AWB) setting. I would recommend shooting in RAW with auto white balance turned on so the scene is close to accurate before you start tweaking in Lightroom.
You can then select any one of the other preset options (Auto, Daylight, Cloudy, Shade, Tungsten, Fluorescent, Flash) from the drop down to change the colour balance if necessary. Try experimenting with these to see what affects you get. Sometimes they can be forced in the wrong direction to produce a strong colour cast and more artistic result. This often works well with graphical images with strong shapes.
Temp And Tint Sliders
More control can be achieved using the Temp and Tint sliders. The temperature slider has a range from 2000-50,000 Kelvin and changes the warmth of your picture. Your image will become cooler (blue) when the slider is moved to the left and warmer (orange) when the slider is moved to the right.
Moving the Tint slider to the left adds a green tint to your image and magenta tint when sliding to the right. There's a range of -150 to +150 when processing RAW files and -100 to +100 with other formats such as Jpeg. Try small adjustments at first to get used to the affect the sliders have on the colours in your photo.
Eye Dropper Tool
The third option is the eye dropper tool selected by clicking once on the icon or using the keyboard's W key which turns the eyedropper on or off.
When on you will see a pop up box that shows the pixels magnified as you hover over the photo with your cursor which has now changed to the eyedropper icon. You can use the scroll wheel on your mouse to adjust the sample area from just a few enlarged pixels to a more condensed range of smaller pixels. Try different settings to see which you prefer.
At the bottom of this preview pop up are the values for Red, Green and Blue. Hover around the photo until you find a neutral square with as near as possible equal values for R, G and B. Click when you find a neutral spot and the colours of the image will change. As you hover around a small preview appears showing the clour change that would occur if you clicking on that area, so you can choose to click or hover around for a better area to sample.
As with all Lightroom processing the changes are none destructive, and all steps are recorded in the History area on the left so you can return to a previous state if necessary.
HSL / Color And B&W Sliders
A lesser discussed correction tool can be found in the HSL / Color and B&W sliders in the right hand feature set.
Click on HSL and Saturation to bring up individual colour sliders. The orange slider when moved slightly to the left can help reduce the orange colour cast you record when shooting in tungsten light. In my photos there was a little blue in the shadow areas which has been removed in the final shot by sliding blue value to the left a fraction.