Which painting technique is characterized by soft outlines and hazy effects?

The technique characterized by soft outlines and hazy effects is known as sfumato. This method, predominantly used during the Renaissance, involves the delicate blending of colors and tones to create a blurred transition between different areas of an image. Sfumato is derived from the Italian word meaning "smoky," which aptly describes the painterly style that evokes a sense of atmosphere and depth. This technique is famously exemplified in Leonardo da Vinci's works, where the smooth gradation of light and shadow enhances the lifelike quality of his portraits and landscapes.

In contrast, chiaroscuro refers to the use of strong contrasts between light and dark to create volume and depth, which produces a more dramatic effect rather than the soft blending associated with sfumato. Impasto involves applying paint thickly on the canvas, resulting in a texture that stands out and often gives a sense of three-dimensionality to the surface. Encaustic is a method that uses heated beeswax mixed with colored pigments to create a rich texture and sheen, which also does not align with the soft and hazy characteristics of sfumato. Thus, sfumato is the painting technique best described by the characteristics mentioned.