Reference : http://muddycolors.blogspot.nl/2013/11/10-things-about-value.html

Greg Machess writes on value :
1. Time of day. When you picture the image or scene, determine whether it’s daytime or nighttime. Immediately. You can see it right away. I know you can. Somewhere in your foggy mind you know what time the scene occurs. You can always change your mind. But decide. Early. Either condition will give you instant impressions about the light in your picture. If it’s night, you have to find ways to illuminate your subject. Nighttime is one giant stage play and you can light it however you want. Street lights. Sirens. Firelight. Explosions. Candlelight. Computer monitors. Lamps, etc. Daytime is not as controlled, but remember it is not always high noon. Stop doing that. Use morning light, afternoon light. Overcast light. Bounce or reflected light. Window light. Use the Sun as a spotlight. Even an indoor scene is affected by the light from outside. Game of Thrones watchers: all that sunlight beaming in through windows, bouncing off characters? Yeah, you know what I mean.

 2. Contrast. Dark foreground played against light middle ground. Vice versa. Also light-against-light areas in the same painting. Dark against dark. The back and forth play of light in a scene, chiaroscurro, adds depth, design, and interest.

 3. Direct the viewer. The eye moves instantly to the highest contrast in a picture. It uses areas of similar values to rest. Yes, the eye rests before it moves on. That’s because it’s processing. It needs time to absorb. Hit it with too much detail, too much contrast up front, and it has to rest. If it can’t find a place to rest, it looks away. Yeah, I know, there are plenty of busy, complicated paintings in the world. You can take all the time you want to study them, but they are not a quick read. Their enjoyment is the time you get to stay with them to figure them out. Simple paintings are fast to read. Aye, but simple can be an even longer read as they stimulate with impact repeatedly. The contrast between sharp and soft, dark and light, entices our minds to explore, rest, explore, rest. THAT grabs and holds the viewer.

 4. Add interest. Let the constant play of values add interest. You can make a painting 90% grey tones, then have one area full of contrast. Wham. Drives the eye to that area. Overall dark piece, lit by one light source? Same deal. Or just the opposite: overall light painting, all values in similar percentages, then one area with a dark passage. Zap. Eye goes right for it. 90% greys, with a dark spot. Or 90% dark with a grey area. Again the same. Contrast the value range and you build movement through the painting.

 5. All color is value. You can paint any color you want, if the value is correct, the affect will be correct. You don’t have to nail the color all the time (although I like to), but you must be able to nail the value. Otherwise, unfocused. Mud. Think of this: you can make skin green. If the value is right, the skin is right. Look at people lit with colored gels from spotlights, like rock bands in concert. Study how the colors don’t change the subject. You’ll come to realize how setting sunlight on skin changes it’s color, temperature, and certainly value, but you’ll still know it’s skin.

 6. Mood is value. Light paintings raise emotions. Dark paintings lower them. Of course you, ya nut, might be excited by dark paintings. Or you may actually be bored by bright colorful paintings. But if you get the values right in your painting, and by that I mean working well within the context you’ve set for the piece, i.e., candlelight vs moonlight, you’ll get the painting to have mood. I love me a moody painting. It lingers on the nerves. You can control what people feel about it. So cool.

 7. Control related values. All elements are related by value in the same picture. Controlling the values through light in one part of the picture determines the affect for other parts, if not the whole. Unless you are painting a stream of consciousness where all bets are off and rules are skewed, the feel of the light is determined by how well one controls all the subtle value ranges throughout. And no, there's no getting around it. Even abstract painters, good abstract painters, must know value first.

 8. Subtle vs Bold. Think graphically. Bold paintings are controlled by value. The best graphic paintings have subtle values played against striking, edgy values. Study at Mucha. Study Ludwig Hohlwein. Yoshida Hiroshi. Edwin Dickinson. Bold. Direct. And oh, so subtle in it’s madness to control your eyeballs.

 9. Photographs lie. Never believe a reference photo. They are representations of reality. NOT reality itself. Yeah, I know. But get over it. The camera is a box with a hole in it that let’s light in briefly so it can expose a moment. But it’s a contraption. It records crudely, no matter what the techies say. Your eye is connected to your brain and breaks an image into thoughts, feelings, smells, sounds, and who knows what. What you see is not necessarily what you can count on. When you make a painting, it has it’s own life and is not a poor excuse for the lack of a camera. Then again…photos can lovingly manipulate value. They can simplify reality so that you can detect the right values to put beauty into your pieces. I love photography. But I never trust it. 

10. Finish with value. Step back from your work. Look it over. Pull it all together by refining the values so they control, manipulate, and interest your eye. If they interest you, they are likely to interest others. But you have to decipher when you’ve looked at it for so long that the values appear correct to you. You must be able to remove yourself from the world you’ve created and be able to look at it with a discerning eye, a ‘fresh’ eye. Like color, the values should move in and out, with rhythm. Like families of color, values need similarities as well as contrasts.

From the compound eye

Intentionally or Unintentionally?

I still remember the various discussions about semiotics in film and animation on this subject...From mise en scene, composition to the deeper meanings of a certain dialogue, theme or any other given visual element presented in the frame. Basically u had two sides, as always. But sometimes things are too obvious...or not?

Collection of various links for video tutorials

All time favorite :
http://www.youtube.com/user/scottrobertsondesign

Others :
http://www.youtube.com/user/FZDSCHOOL?feature=watch