Hard and Soft Edges in Painting: Where to Use Each

An edge is where two shapes meet. A hard edge is a sharp break, a soft edge blends over a short distance, and a lost edge disappears because the shapes on either side are the same value. Painters vary them to steer the eye and to show form and distance.

Hard, soft and lost

• Hard: a clean break, such as a sunlit wall against a dark doorway.
• Soft: one shape fades into the next, as a cheek turns from light into shadow or a cloud meets the sky.
• Lost: two shapes of the same value, and often similar color, run together with no visible edge, like a dark coat against a dark background. The viewer fills in the missing edge.

In a good painting most edges change along their length: hard in one place, soft or lost a little farther on. Painters call this lost and found. Harold Speed, in The Practice and Science of Drawing (1913), wrote that a good artist "seldom lets a sharpness of edge run far without losing it occasionally". An edge that stays sharp all the way along looks stern, he said, and one that stays soft looks feeble.

Why vary them

You only see fine detail in a small patch at the center of your gaze, about the size of a thumbnail at arm's length, as DiPaola, Riebe and Enns note in a paper on Rembrandt's portraits. In front of a real scene, whatever you look at is sharp and the rest isn't. Paint every edge equally sharp and you show each part as if you'd looked straight at it in turn; Speed found that such a picture doesn't hang together.

Where to put hard edges

• Where you want attention. A hard edge between a strong light and a strong dark pulls the eye, so keep your hardest edges for the focal point.
• Where a form changes direction abruptly, such as the corner of a building.
• Where a cast shadow starts. Leonardo noted that a cast shadow is most blurred where it is farthest from the object casting it, and that the bigger the light, the vaguer the shadow's outline. A post's shadow is crisp where the post meets the ground and softens as it stretches away, and shadows are crisper in sun than under an overcast sky.

The first of these has exceptions. Speed pointed out that in Titian's Bacchus and Ariadne, in the National Gallery in London, the edges of the flesh are soft everywhere, and the sharpest edges are on small things: a piece of white drapery on the arm of the cymbal player and a white flower on a boy's head. He thought the soft edges gave the main figures largeness and mystery, and that the crisp accessories restored the balance. What counts is how an edge compares with the edges around it.

Where to soften or lose them

• Where a rounded form turns away from the light. The edge between light and shadow on a cheek, an apple or a tree trunk is soft. Leonardo warned that shadows with edges you can't make out must not be painted sharp, "lest your work should have a wooden effect".
• With distance. Leonardo's rule was to make outlines less definite as objects get farther away, and more so the hazier the air.
• Away from the focal point, especially near the edges and corners of the canvas, where a hard edge pulls the eye out of the picture.
• Between shapes of nearly the same value. Losing the edge joins them into one bigger shape. It can also move the eye: DiPaola and his colleagues describe how the eye follows edges of strong contrast and moves on where one disappears, so lost edges can lead it toward the focal point.

Why photos get edges wrong

• Focus. A camera focuses at one distance. A photo may be sharp from front to back, so the background competes with the subject, or sharp only in a thin slice, so a foreground you wanted is a blur. Neither is a decision about your painting. Phones can also add blur: in Portrait mode, Apple says, the camera "creates a depth-of-field effect", and you can change how much afterward.
• Sharpening. Imatest, which makes camera-testing software, says the JPEG from almost every digital camera is sharpened, and that some cameras overdo it, mostly low-end compacts and camera phones. Sharpening raises the contrast along edges, and too much leaves a halo beside them. Copy that and every edge in the painting comes out equally hard.

How to see edges

• Squint. Edges that stay sharp when you squint are the hard ones. Edges that vanish can be painted soft or lost.
• Look at the whole scene, not each part in turn. Speed noticed that if you focus on each object separately, you find hard edges almost everywhere. Take in the scene as one view and the edges start to vary.
• Blur the photo. The Simplify slider in the notan and value study maker blurs the photo before splitting it into values. Where two shapes land in the same value, their edge is a candidate for losing.

The Paintsight app's hard and soft edges view shows how sharply shapes meet in a reference photo. Use it to find the edges, then decide which ones to keep.

Painting them

• Hard: place one loaded stroke and leave it. Going back over an edge softens it.
• Soft: paint the two shapes wet into wet and draw a clean brush along the join. In watercolor, run a damp brush along the edge before it dries.
• Lost: paint the two shapes the same value where the edge should go, and carry one into the other.

Speed advised students to err on the side of hard edges while learning, because hard contours force you to solve the design. Loosen them once the drawing is sound.

Sources

• Harold Speed, The Practice and Science of Drawing, 1913, chapter XIII, "Rhythm: Variety of Mass", the section "Variety of Edges", on lost and found edges, Titian's Bacchus and Ariadne, focus and advice to students. Project Gutenberg.
• Leonardo da Vinci, The Notebooks of Leonardo da Vinci, translated by Jean Paul Richter, 1888, sections 194 (the edges of cast shadows), 225 (outlines and distance) and 236 (soft shadow edges). Project Gutenberg.
• Steve DiPaola, Caitlin Riebe and James T. Enns, "Rembrandt's Textural Agency: A Shared Perspective in Visual Art and Science", Leonardo 43, no. 2 (2010): 145–151, on the size of the area of sharp vision and the lost-and-found edge.
• The National Gallery, London, Titian, Bacchus and Ariadne, 1520 to 1523.
• Imatest, Sharpening, on in-camera sharpening, overshoot and halos.
• Apple Support, Use Portrait mode on your iPhone.