This may seem like an exaggeration but the most important aspect of the painting will be the four edges of the canvas, or paper. Crazy, right? But here's the deal. No matter what type of composition you choose it must fit well within the four lines, or edges of the picture plane. If it doesn't your painting will become tired and no matter how skilled you are with brushwork and color the painting just will not work.
Here's What You Need To Know
Let's revisit some of the composition examples and we will focus on edges and angles. Basically, the tension and dynamics of how it all relates to the four most important lines. Example One: Centered Portrait First look at the four edges. They are obviously square and straight. Now have a look at the cow to see how angles were used to create tension within the picture plane. Example Two: Little, Or No Tension Now have a look at a similar centered portrait but this time it appears much weaker. That's because the composition does not create tension with the four main edges. The only edge it touches is the bottom. Example Three: Cows In Landscape This one shows how the composition mingles well with the four main lines. The cows are not centered and the horizon doesn't divide the painting in half. Example Four: Cows In Landscape But No Connection In this illustration the artist clearly didn't consider the edges of the canvas. The cows are places in the center, the horizon divides the painting in half, and there's little interaction with the edges as most of the shapes do not touch them.