What is the difference between saturation, vibrance and luminance?  I found myself in the midst of a class on advanced tools and techniques for Photoshop and I watched a young man go screaming for the saturation slider and just shredding what should have been a reasonable correction.  I was not sure he was going to get much out of the class as many of the concepts to be covered required a foundational knowledge of Photoshop to get through.

Let’s start out by defining each term and then where and how to execute their effect.

Saturation means what it sounds like, and as a correction tool, its remarkably dumb. When you want to beef up all the colors in an image, and I mean ALL the colors, the Saturation slider is your friend. It adds punch to all the colors evenly, regardless of need. It should be noted a little Saturation goes a long way and less is better.

 

The pair of images above are a good example of an image where all the colors appear to be flat or subdued. This is one of the rare instances where adjusting saturation would be of benefit. Even then, caution is necessary as it can quickly become overdone.

Vibrance is a much smarter tool in Photoshop for bringing out the color in an image. In most images, some colors are well represented while others could use a bit of bumping up. Here the Vibrance slider is your friend. Vibrance is a very smart tool and very forgiving as it detects which colors are below a given threshold and affects them more than others. What more, if all the colors are a bit flat, it will boost them somewhat evenly. If I had to choose between Saturation and Vibrance for color correction, Vibrance is the better tool. The effect is much more realistic.

 

This pair of images is a good example of when an image needs vibrance adjusted. Photoshop determined which colors were below a certain threshold and boosted only those colors. In this instance green with some of the outlying area. It should be noted, you are actually shifting the color, not making it brighter. If you are intent on printing your image, you may want to check the gamut, to make sure your printer is capable of producing the brighter colors.

If you are intent on only highlighting the leaves, please read on…

Luminance refers to the absolute amount of light emitted by an object per unit area, whereas luminosity refers to the perceived brightness of that object by a human observer.

Objects either absorb colors or they reflect them. Using the title image, the leaves absorb much of the light spectrum, such as red or blue, and reflect green with a bit of yellow. The trick now is to isolate the colors and raise the amount of light reflecting in that color.

The best way to highlight the leaves, is to create a Luminance Mask. This give you a great deal of control over the brightness of the chosen color.

 

In the image above, in Photoshop I have created a duplicate layer and changed the exposure (exposure, not brightness) by two f-stops. This will be the amount of light I want the leaves to radiate in respect to the original leaves in the image.

 

Switching over to the Channels, I have selected the green of the RGB pallet. Then I duplicated the channel for editing. If you can not see the channels tab, on the menu bar, going to “Windows > Workspace > Essentials (Default) will resort the channels tab.

 

In editing the duplicate channel I dramatically increased the contrast of the channel and then used a feathered brush at about 70 percent opacity to black out much of the surrounding area to a greater or lesser extent.

Holding down the control key (PC) or command key (Mac), you click on the duplicate green channel. This will select the highlighted areas of the green channel and you can see the “marching ants” around parts of the channel that are above an arbitrary brightness selected. It may not be all of the masked area, just the important ones.

 

Back to the layers menu, select the +2 exposed layer and click on the mask layer tool. It is the rectangle and circle at the bottom of the layers menu and boom…

You have raised the light on the leave by two f-stops, while preserving the darker surroundings. If you need to boost the brightness further, do so by changing the exposure on the masked image. If you want, you can continue to edit the mask, darkening areas further. Simply make sure you have the mask itself selected.

If you intend to continue editing the image itself, make sure you have selected the original layer. I am referring to the content of the image. Should you feel the need to change the vibrancy, such as to bring it into gamut for printing, selecting the masked layer is necessary.

 

From start to finish, the Luminance Mask has brightened the leaves and kept the surrounding area mostly alone. In the gallery above, I’ve included the masked area with a layer of black to show how the mask as worked. This may seem to be a great deal of effort, but it goes rather quickly as you experiment with this technique and add it to your skillset.

One caveat here; The final image was not my final choice. I orient my work towards printing and the colors were far to bright and way, way out of gamut. When soft proofing  the image above, at least 40 percent of the image was un-reproducable with my printer, or any printer for that matter.  Indeed, I often use soft proofing as a check to excess use of the vibrance slider. This keeps my images well within the images original colors, of which I hope to write about later.

Enjoy your day.