The human eye can distinguish anywhere from 100,000 to 10,000,000 variations of color yet it can only distinguish approximately 30 variations of value (tone). That's totally understandable since thousands of color variations fall within the same range of value.  When working with paint pigments, it's difficult to mix more than ten discernible values.

To simplify the painting process when making Value (tone) decisions, many artists confine themselves to thinking in either a five-step value scale, a seven-step value scale or a ten-step value scale.  When I first began focusing on manipulating value for my own purposes, I used a five-step value scale.  Now, I generally use a seven-step value scale depending on the atmosphere/mood/design of the artwork.

I once made three charts using all the tubes of oil paint I owned by placing swatches of full-strength pigment in a grid corresponding with the appropriate grayscale value.  I was surprised at how many pigments fall in the darker value ranges in spite of the fact that they appeared to me to fall in the mid-value range.  All three charts had to be extended to a second canvas grid in order to accommodate the rest of the pigments that coincided with the darker values. The images below show only the first canvas of each of the three grids.

*** Remember when talking with other artists they may be numbering the values in the reverse.  Some think of black as 10 and white as 1.  In all of my courses, I will refer to value according to the scale pictured above, black as 1 and white as 10.

Why is value important? 

It is through the choice of value, not color, that we achieve the illusion of light being cast on objects, of reflections and shadows. It also through the choice of value that we achieve strong design and composition. When we choose the value well, it really doesn't matter what color we pick to express that value, we will still achieve the illusion of light that we are trying to express.

An anecdote ...

To be honest, I didn't completely believe the previous sentence until I conducted an experiment painting en plein air in Tyaskin, Maryland.

I set up my easel up in the early morning as the light streamed through a straight row of tall pine trees on a piece of property owned by a paper company.  I planned on presenting a Color Value lesson in a workshop and wanted to have an example to show the class.  I squeezed yellow, green, red and blue oil paint from the tubes onto my palette.

For the first time, I was concerned about being visible as I painted.  More often than not, when I painted in this rural area of the Eastern Shore of Maryland, one or two pickup trucks would stop by throughout the day to see why a lady from New Jersey would be on a dirt road in the swamp.  The curious driver would stop to ask what brought me, as he thinks of it, to the most beautiful place in the world.  He'd chat for a bit, share his mother's recipe for muskrat stew and then move on.  An hour or two later, the pickup truck would appear again.  The driver would check up on me and see how the painting was coming along. Though some of the young men had traveled the world in the military, they couldn't think of calling any other place home.  I thought for sure that anyone who saw me painting that day might think I was on drugs. My plan, if anyone stopped, was to casually swap the painting with a painting I'd done the day before, one that had a more normal color palette.

I painted the entire painting using only those four pigments straight out of the tube: yellow as my light tone, red and green as my middle-tones, blue as my dark tone.  I used both red and green as middle-tones to illustrate that they are generally the same value when they fall opposite on the color wheel.  I used a maple leaf green and a fire engine red, not a yellow-green and a red-violet.

A half hour had gone by without a passing vehicle.  I'd just concluded my first fairly frightful oil sketch experiment. As is my habit, I walked about thirty feet back to view it from a distance. Before I could return to my easel, a pickup truck pulled in. The young man hung himself out the window, his mouth agape.  "How do you make that look so real?  I've never seen a painting capture the light coming through the trees like that!  I've never seen such a real-looking painting in my life!  That's amazing!"

Hmmmmm.  I thought he had to be joking, yet he seemed totally sincere.

"You don't think the colors are a bit strange?" I asked.

"Hell no.  If you gotta use those crazy colors to get that sunlight shining through the trees, I guess that's what you gotta do. I really like it.  You don't mind if I send a few of my buddies by to take a look do you?  You'll be painting here for awhile?"

I painted in that spot for another three hours, continuing to experiment with these basic colors.  Three more pickup trucks stopped by and let me know that their friend suggested they come by.  They all liked the bizarre little paintings and came back once or twice more to see how things were going.  I never can predict the people I'll meet or the words that will be spoken when I paint outside in a city, mountain or remote rural area.

Below is a black and white snapshot of that same painting.  Observe the values (tones):

What's the point of telling this anecdote and showing you these examples? I want to bring your attention to the importance of making VALUE-BASED decisions.

Remember ... it's through the choices of value, not color, that we achieve the illusion of light being cast on objects, of reflections and shadows.  It's our choices of value that determine the shapes a viewer notices and those the viewer doesn't notice.  Our paintings will be more masterful when we hone the skill of determining excellent value choices.