A good judgement of tonal values is difficult, because our brain easily gets tricked. With the following tips, you can avoid the most common mistakes.
The two main reasons for the misperceptions are:
1: we get tricked by surrounding values
2: we think we know what we see
Surrounding values influence our perception
A color or value never stands on its own, it’s always surrounded by other values. When you see a light part in dark surroundings, you may interpret that light part lighter than it actually is.
It can be easily shown with the following example. It’s hard to believe that te grey lines below are exactly the same value.
It gets even harder when we add colors, because colors can do very tricky things when placed next to each other.
So what does this tell us? We have to be very cautious when we see a light part in a dark surrounding or a dark part in light surrounding.
In the picture below, the lighter part in the hair can be easily misinterpreted as a light value, but actually it’s very dark. It’s lighter than the surrounding colors, but not nearly as light as you might think.
And the other way around, darker parts in light environments aren’t always that dark. The shadows of the folds in the picture below can be easily mistaken for a dark value, but the value isn’t that dark.
We get tricked by what we think we know
A lot of times we get tricked because we think we know what we see. In the example below we see a book with (what we know to be) white pages on a (what we know to be) a black bench.
But due too the lighting conditions, the pages in this instance are reasonably dark, while the top of the bench contains a lot of reasonably light colors.
When we want to paint this scene, chances are that we’ll paint the pages of the book too light and the top of the bench too dark.
We can prevent ourselves from getting tricked by just knowing that light colors can be very dark and dark colors can be very light. We just need to pay attention.