Color Theory Basics – Saturation and Chroma

Continuing our discussion of Color Theory we move on from Hue to Saturation and Chroma. These are two closely related but distinct properties of color. Learning these distinctions and understanding them implicitly is what will give us a deep and sophisticated understanding of the uses of color.

In order to discuss these ideas we must first take a quick look at color media for lighting. The three major brands of color filters are Lee, Rosco, and Gam. Each of them produce similar but importantly distinct ranges of colors. Regardless of the particulars of the color media they all operate in a similar manner.

Clear incandescent light emits a range of colors in the visible spectrum. In fact, it is that range which makes us perceive it as White light. A color filter is precisely that, a filter which eliminates all excess wavelengths to allow only those wavelengths desired by the designer to get through. A filter like Lee 201, for example, pulls out many of the wavelengths along the Red and Amber end of the color spectrum to give a clean 5700° K color. We will get more in depth on Color Temperature and lighting design in a later post. But for now it is useful to know that L201 is a pale Daylight color.

If Hue is what we would commonly call the color, then Saturation and Chroma deal with different aspects of brightness. Saturation is how much of a given Hue might be found while Chroma deals with where that Hue falls in a spectrum from Gray to full Chroma. Let’s look at Saturation first.

Saturation is how much of a given Hue is in the filter. Low saturation is closer to White light and colors in that range are called Tints. High saturation has a lot of one particular Hue, are very chromatic, and we call colors in that range Shades.

Tints tend to allow a lot of light to pass through. It can be tempting to forgo heavily saturated colors, particularly deep and rich Congo Blues, because they allow so little light through (1-4% typically) that one might easily choose a lighter saturation for greater transmission. It is important to not be afraid here. Bold color choices demand a degree of risk. Even though there is such a small amount of light actually getting through the filter, the effect can be quite strong. If you need the saturated color, use it.

Since we looked at very saturated and chromatic colors in our exploration of Hue I thought it would be nice to look at some Tints this week. On the left you will see the Rosco CTB filters. You can see the colors ranging from nearly White to a nice middle Blue.

You will also note that while the Hue of these colors is a Blue, they tend to fall closer to Gray than a purely chromatic color. Thus we see here an example of variance by Chroma.

Below we have a low saturation Red, commonly referred to as Pink. What is interesting in this image is the spectral analysis of the filters. The black curve in each image shows us how much of each color in the visible spectrum is contained in the filter. You will note that while the warm end of the color spectrum, from the end of Yellow through Red, remains the same we see a marked shift in the middle Blues through Green and into Yellow. This allows us to see not only how much color is filtered out but also how each filter relates to the other one.

On the right hand side of the picture we see the manufacturer’s name and number for the filter. Then below that is the Transmission. This tells us how much light passes through the filter. The lower the Saturation, the higher the Transmission.

Because all color is relative, nothing is objectively a Tint or a Shade. Comparing G108 and G105 we see that 105 is a Shade of 108. Yet compared with a solid Red like G250 we see that G105 is also a Tint.

We will go much more in depth on the relativity of Tints and Shades when we cover Missing Color Syndrome in the next part of this series. For now, let’s move on to some practical applications.

Returning to our example of the Woman-in-a-Red-Dress we can immediately see an application for color of differing saturation, yet utilizing the same Hue. Our woman enters and the lights change. We turn on a Frontlight special in G250 but immediately notice that while the dress looks fantastic, our Woman has turned rather garish. Loving the dress, but hating how our actor looks, we decide to turn on our G108 Crosslight. The effect now is of a deep red dress with rich and brilliant shadows sculpted by a pale Pink Tint. Because of the G108, our actor’s skin looks beautiful and healthy. We have just achieved a happy costume designer, a happy actor, and a happy director. All with some simple color tricks.

Beware: death by Tints.

While the proper use of tints, as we see above, can be a real life saver, they can also cause us unbelievable headache. I have seen plenty of Yellow and Pink costumes ruined by a “why bother blue” that had just too much Green in it. Colors, and by extension actors, can disappear in what appears to be white light all because of a tint we did not pay enough attention to. Healthy actors can look sick because that Amber front light we fell in love with in the studio has just a hint of Green.

Knowledge of Saturation is a useful tool in the designer’s tool kit. Without such information, our Woman-in-a-Red-Dress would be left looking like some freakish alien, instead of a stunning ingenue. Using Shades to fill in shadows and Tints to highlight can be a great way to sculpt a figure with color.

We need not use the exact same Hue either. G250 which falls pretty solidly in the Red camp could easily be paired with sympathetic colors in tints. Instead of the Magenta and Amber I proposed in the post on Hue, one could use Tints like R53 (a Lavender) and R302 (a pale Rosy Amber).

A solid understanding of Saturation and Chroma will allow you to really start mastering the use of color. If you missed my post on Hue I would encourage you to go back and read it through. In later posts I will be exploring Missing Color Syndrome, Dominant and Recessive Colors, Color Correction, Gray, The Effect of Lamp Type, and Additive vs. Subtractive Color Mixing.

I hope you found this useful. Please take any new ideas and start experimenting. We will continue to build on these concepts throughout this series. Stay tuned.

Was this useful to you? Please let me know what you thought in comments. Or leave any questions you may have and I (or other commenters) would be happy to answer.

Be Sociable, Share!