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| Dappled Ambient Daylight |
The quality of light
varies a lot during the day but the changes to night and artificial light can
be even more dramatic. This is even more obvious in any photographs we take.
The artificial light normally has a different colour temperature and this may show
up as a colour cast. (orange in my example below)
This colour cast can
be fixed by a process normally know as
White Balance, which is just a name for
the task of removing that cast and it will vary depending on where you
undertake it. It can be undertaken in digital cameras by the camera as your
take the picture, often as little icon in the menu for daylight, sunny, cloudy,
artificial light etc).
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| Jpeg direct from camera showing orange colour cast despite AWB |
Most modern Digital cameras have an AWD (Automatic White
Balance) setting that the camera best guesses the colour temperature (usually very well). If
you are taking a jpeg image this adjustment is applied to the image, if you
Capture in RAW the adjustment is applied to the preview but the un-altered data
from the sensor is also stored and the white balance is easy to change later.
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| RAW image post processed with a WB adjustment |
Most Photo
Processing software also has white balance tools built in, and it is possible to make the same adjustments to removed colour casts in the post-processing
step (as I have undertaken in my example above). How the adjustment is carried out
varies with each package but most offer a simple approach using a dropper tool
(that is pointed at part of the image that should be a neutral colour) through to
sliders that adjust the colour temperature in degrees Kelvin (how colour
temperature is measured)
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