Better Color Saturation
Adjusting Saturation Using The Channel Mixer
When someone tells you how to boost color saturation (or reduce it) they usually will point you to the Hue/Saturation tool and be done with it. Unfortunately that isn’t the only option out there nor is it necessarily the best. The Channel Mixer can be used to great effectiveness and with much better results in most cases.
For small and quick adjustments the Hue/Saturation works quite well, but for greater adjustments I find its effects to be less natural in appearance than I like. It also has a tendency at times to be unkind to high-ISO images making noise much more unpleasant to look at.
Instead of simply increasing the saturation value of each pixel like the Hue/Saturation tool dœs, the Channel Mixer will pull information from the other color channel(s) and add it to the channel you are saturating. In essence it is boosting saturation using the data that is already in the image rather than creating information from nothing.
Overview of the Channel Mixer
When looking at the Channel Mixer for the first time, it may seem a bit complex, but in all actuality it is quite simple to use. Out of the three groups of controls the Channel Mixer has you will only need to worry about the “Output Channel” and “Source Channels” controls for what we’re doing here.
The Output Channel drop-down lets you specify which channel (Red, Green or Blue) you wish to work with. The three sliders below that are used to adjust what percentage of each Source Channel will be used for the currently selected Output Channel.
Wile mixing channels it is important to keep the values of the sliders totaling 100%. A value greater than 100% will “overexpose” the current Output Channel and a value under 100% will “underexpose” it. Both of which can create an unwanted color cast. Also to prevent color casting it is important to make sure the values of the two reduced sliders are equal to each other. In other words, if you increase the Red slider to 120% the Green and Blue sliders must both have values of -10%.
Although all this may sound a bit complicated, don’t fret. Once you start playing with the settings it won’t take long to get the hang of it.
Boosting Saturation
Now that we have the basics of the Channel Mixer down let’s boost some color saturation.
Bring up the Channel Mixer by clicking on the Create New Adjustment Layer button that is at bottom of the Layers Window (see image at right) and then selecting Channel Mixer… from the menu. The same can be achieved via the File Menu: Layer » New Adjustment Layer » Channel Mixer…- For the Red Output Channel enter an even value for the Red Source Channel. Half of the increase over 100% will be used for the other two Source Channels. As an example the image on this page is using the values of +126% for Red and -13% for Green and Blue. The amount of saturation you will need (or want) will of course vary depending upon subject and your creative intent.
- Repeat step two for the other two Output Channels and hit “OK.”
There you have it; a fairly simple procedure that gives pleasing results. The following is a before and after of my example photograph.
Color Desaturation
Desaturating an image works on the same principle as saturating an image. If a value over 100% saturated an Output Channel then a value below 100% will desaturate it. Again the total of the Source Channel values must remain at 100%.
An example of desaturation would be to set the Source Channel values to 80% for Red and 10% for Green and Blue.
Be Creative
The procedure I mentioned above is just a guideline that will work for most cases. It’s by no means the only way to do it and some creative experimentation can provide some very pleasing and/or unique results. There is a great amount of control available to you with the Channel Mixer. Quite a bit can be done to an image with very little loss of color information (or no loss if following the 100% total rule).
Actions
Actions for this tutorial can be found on the Downloads page.