What technique did Leonardo da Vinci pioneer that involves soft transitions between colors?

The technique that involves soft transitions between colors, which Leonardo da Vinci pioneered, is known as sfumato. This method allows for a subtle blending of tones and hues, creating a hazy, atmospheric effect that improves the illusion of depth and volume in a painting. Sfumato is characterized by the delicate gradations of light and shade, which enable the artist to depict forms in a less defined and more nuanced manner.

Leonardo's use of sfumato is evident in many of his works, where it contributes to the lifelike quality of his subjects, particularly in the soft outlines of figures and landscapes. This approach contrasts sharply with more defined techniques, allowing for a more naturalistic representation of scenes.

Chiaroscuro, while related, specifically refers to the contrast between light and dark in a work of art, which highlights volume and three-dimensionality, rather than the gradual transition of colors. Impasto involves applying paint thickly to create texture and contrast in light reflection, and fresco is a technique of mural painting applied on freshly laid wet plaster, which is around for capturing vibrant color but does not primarily focus on the blending of hues.