It
seems that brightness, contrast, saturation and sharpness are the four simplest
controls of image. On the surface, they are four mutually exclusive controls. However,
as a matter of fact, they are related to each other and intertwined in a way to
such a degree that the change of any one of them will lead to rather
complicated effects in the image in terms of the other three controls. Only
when users have mastered a rather good knowledge about how these four controls
are related and how to make use of them in a harmonious way can users achieve
the desired image effects in the end. It is wise for users to think twice about
what they really want to accomplish before taking actions to change the
brightness, contrast, saturation and sharpness, whether to increase or to
reduce them.
Generally
speaking, the overall effect of brightness, contrast, saturation and sharpness
varies according to different contents in the photo. Take the increase of
contrast as an example. With the increase of contrast, the shadow will be
darker while the highlight will be brighter. However, if most details in the
photo are very bright, for instance, an overexposed sunset, then we will end up
with less contrast with the increase of its contrast. The reason is that there
is no shadow in the photo at all, which means that the separation of shadows
and highlights in an image containing only highlights will just compress the
highlights. As a result, the image will get less contrasty. We can safely come
to the conclusion that it is vital to have a good understanding about how these
four simplest controls affect each other and how they work in a harmonious way.
It is a bit of art to use brightness, contrast, saturation and sharpness to
achieve a balance.
