The use of lines is a major design tool that the photographer can use to structure the image. Line becomes apparent when the contrast between light and dark, color, texture or shape serves to define an edge. The eye will instinctively follow a line. Line in a photograph can be described by its length and angle in relation to the frame (itself constructed from lines).
Horizontal and Vertical lines
Horizontal lines are easily read as we scan images from left to right comfortably. The horizon line is often the most dominant line within the photographic image. Horizontal lines within the image give the viewer a feeling of calm, stability and weight. The photographer must usually be careful to align a strong horizontal line with the edge of the frame. A sloping horizon line is usually immediately detectable by the viewer and the feeling of stability is lost.
Vertical lines can express strength and power. This attribute is again dependent on careful alignment with the edge of the frame. This strength is lost when the camera is tilted to accommodate information above or below eye level. The action of perspective causes parallel vertical lines to lean inwards as they recede into the distance.
Suggested and Broken Lines
Line can be designed to flow through an image. Once the eye is moving it will pick up a direction of travel and move between points of interest. The photograph to the right is a good example of how the eye can move through an image. Viewers of this image will be guided towards the distant hills on the right side of the image. The lines created by the dry stone wall and the converging lines created by the ridges of the hills all serve to guide the viewer in this direction. A photographer can strategically frame an image and position the lines within the frame to aid this process (note the dry stone wall entering the image from the bottom left-hand corner). The use of simple and uncluttered backgrounds (without distracting detail) can also help to isolate focal points that use line as an important part of the design.
Whether real or suggested, these lines are more dynamic than horizontal or vertical lines. Whereas horizontal and vertical lines are stable, diagonal lines are seen as unstable (as if they are falling over) thus setting up a dynamic tension or sense of movement within the picture.
Curved line is very useful in drawing the viewer’s eye through the image in an orderly way. The viewer often starts viewing the image at the top left-hand corner and many curves exploit this. Curves can be visually dynamic when the arc of the curve comes close to the edge of the frame or directs the eye out of the image.