Related optical effects that combine to give the impression of depth. Explored in Renaissance paintings, and some from the 19th century.
aerial perspective
More important than perspective projection are cues including depth order, relative size, height in the picture plane, and aerial perspective.
Blurring for dramatic effect, and to mimic photographic depth of field effects, were used in the 19th century, but motion blur came later.
There were few good reasons to blur what should be sharp edges in paintings. Aerial perspective and Vermeer’s unusual optical effects explored in paintings.
Its peak with Bonington, Friedrich, Corot and others. Decline in Impressionism to deliberate omission in ‘primitives’ such as Cézanne and Astrup.
The way that distant hills fade in contrast, detail and colour, and how their hue shifts towards cooler colours. From Antonello (1475) to Thomas Girtin.
Aerial perspective includes reduction in contrast, reduction in chroma, and colour shift towards ‘cooler’ i.e. more blue, colours. But it can be more complex.
Painting is about form, light, and colour. Here is a short summary of the practical points developed in the previous articles on colour.
The Eclectic Light Company 