Today’s Question: I recently read some Photoshop image-optimization advice to increase Vibrance while at the same time decreasing Saturation a little (in either Lightrom or Adobe Camera Raw). And then I observed the same behavior when clicking the Auto button [for automatic adjustments in the Basic set of adjustments]. Why would this be recommended and what’s the effect on the image when doing so?
Tim’s Quick Answer: This is indeed a good approach that I often recommend. The basic idea is that Vibrance enables you to bring up the saturation of colors that aren’t very saturated. However, sometimes that brings the total saturation up too high, and a slight reduction in the value for the Saturation slider provides a compensation in that case.
More Detail: When you increase saturation using Vibrance, the saturation is increased more for color that are not very saturated than for colors that are saturated. This helps you boost the overall saturation without causing relatively highly saturated colors to start looking somewhat cartoonish.
I see the Vibrance control as providing a method to essentially balance out the saturation levels in the image. As you increase the value for Vibrance, in effect the colors with relatively low saturation levels are getting closer in saturation to the colors that have relatively high saturation levels.
Sometimes, however, you may find that in order to bring the colors with low saturation close enough in overall saturation to the colors with high saturation, you need to push the Vibrance value up a bit too high.
The Saturation slider provides a more linear adjustment than the Vibrance slider does. So when you need a high setting for Vibrance to get the balance of color saturation right, you can use a negative value for the Saturation slider to lower the overall saturation for the image.
For example, with some images I’ll find that I need to push the Vibrance up to a value of 75 or more before the balance is right between colors in the image. But at that point the overall saturation might be too high. In that case, reducing the value for the Saturation slider a little (perhaps a value of negative 10, for example) improves the overall appearance of the photo.