Photoshop: how to change the saturation retaining hue and brightness?

Question

I would like to to change the saturation of all the color of an image to a fixed amount retaining the original hue and brightness.

One could think that this is easily achieved by the sautration blending mode. In fact you can read on the web tutorials things like this:

The Saturation blending mode applies the saturation of the blend color to the base image while retaining the hue and luminance of the base image.

But this is actually false as far as I can see. If I use a 100% saturation blend color the resulting color will not have 100% saturation and the resulting saturation will also depend on the brightness of the blending color.

So what is the "saturation" mode doing? Is there a way to change the saturation of the color of an image to a given desired amount (retaining original hue and brightness)?

Answer 1

To achieve your desired result, I don't think Saturation Blending Mode is what you are looking for. I believe you want to apply a Hue/Saturation Adjustment Layer in order to increase the saturation of your image.

To do this, go to Layer > New Adjustment Layer > Hue/Saturation. This will create a single layer where you can adjust the Hue/Saturation to your desired levels. To apply the adjustment layer to only one other layer (instead of all layers below it), right click on the adjustment layer, and select Create Clipping Mask.

Edit: To clarify, Saturation Blending Mode affects how a layer interacts with the layers below it, not its own saturation.