This is a very simple idea lost on a lot of artists. A convincing painting must look 3-D to hold a viewer’s interest. It isn’t hard, but many miss it because it’s obvious.
It’s OK to Borrow to Create and Illustrate
First I want to thank www.marcellobarengh.com where I flagrantly took pictures of his video since I have never videoed painting an apple. I do this only to illustrate not to take his work as mine.
Outline The Shape
Let’s start with the easy step everyone can do. Outline a shape. The goal is a 3-D flat 2-D representation. Since we are going to have light, medium and dark versions of the green for the apple, we start with the medium green. Our light source is from the upper left so we leave an unpainted portion on that side to allow for light green and a glint of white in the brightest spot. That will be the reflected sun or light bulb.
Next, we paint in the darkest darks at the exact opposite of the light source. THIS is where many beginners get it wrong. They will often either over darken one whole side or leave it a uniform green on all sides. In every painting, there are always tiny amounts of darkest darks and lightest lights. These are the accents to your painting.
The darkest dark, essentially black, is on the edge of the bottom of the apple against the table. As you move up the back of the apple, light is reflected from the surroundings onto the backside. The higher you go, the more light there is.
Block in Each Color
Notice he added more dark green to the backside and light green to the front. He added yellow which would be the reflected color from the light source. A spot of white is left for the bright glare of the reflected bulb or sun, just like the tiny glint on an eyeball.
Now comes the detail, adding yellow spots to show the skin of the apple. No other green was added in the middle because we started with the overall color first. Now, this guy is good, adding texture lines in black for the shadow area in the indention of the apple’s top and the stem.
Notice how just adding a shadow on the backside and light in the front informs you of the light direction. It also now looks 3-D. Th eB&W slide below demonstrates the value steps required to create a convincing 3-D picture.