Let's take a look at a couple images by Craig Mullens. Craig knows what he's doing ... and I don't have time to draw something appropriate for this tutorial.
On the right I've pointed out 3 basic uses of diagonals within his image.
- RED - Basic perspective principles apply here. Craig uses these diagonals to give the image depth and scale.
- WHITE - These diagonals are used to direct the viewer's eye towards a specific point of interest. In this case, the eye tends to travel in a downward left direction and the viewer is able to easily concentrate on the sniper and eventually the birds. You'll also notice that some of the red lines serve the same purpose in this image.
- CYAN - An opposing diagonal is used in Craigs image to halt the downward travelling of the viewer's eye. This opposing diagonal causes the viewer to pause and focus on the character. An opposing diagonal is almost always used near a point of interest in an image.
Here's another great example ...
- RED - Again ... basic perspective principles are used to add depth and scale. Notice also that these perspective lines almost form an arrow that points to the right. This tricks your eyes into viewing the image in this direction.
- WHITE - Craig uses two really strong diagonals in this image to draw your attention to the interior of the car and the girl sitting within. Notice that her leg causes a break in the flow of the perspective guidelines and serves a double purpose in this instance. The rightward direction is abruptly broken here and you're forced to ponder the area where the girl is seated.
- CYAN - Another breaking point is created by the open door. This and the right leg of the girl both occur at or near the point of interest in this image.
All three types of diagonal elements in these pictures can (and will) serve multiple functions. So it's difficult to say that any one diagonal is specifically for a single purpose in an image. I've tried to summarize in these two examples what the main purpose of these diagonals may be.
Diagonals can be used also to add more action or movement to an image. Take a look at the images below by, fantasy artist, Frank Frazetta and see diagonals in action.
The theory of directional diagonals is pretty simple. And of course, like all art theories, the rules are definately there to be broken. Horizontal and vertical lines can be used just as effectively to the same purpose. Other theories (i.e. color, curves or line weights) can be used in conjunction or in replacement of diagonals to achieve the same results.
This is just one extra tool for your use ... enjoy!
If you have any questions or have some additional info about diagonals that I didn't include in this post, feel free to reply here. I'll give any additional insight if required.
Apologies to Craig Mullens if he objects to me scrawling over his images. But they were 2 excellent images to illustrate this principle from.