In art:
if contrapposto is an aesthetic asymmetrical arrangement of the human figure and chiaroscuro is an effect of contrasted light and shadow.
What is the term for a sculpture or painting that has a balance of fine detail and areas that are left rough (ébauche) or without any detail.
And yes, I see the irony in asking on a English language forum for a word might be of Italian or French extraction.
We may call such sculpture or painting 'relief' or 'relievo'. But from the suggestions in the post we are more prone to calling such art work "SUNKEN RELIEF/INCISED RELIEF" or even "INTAGLIO". As Britanica.com has it, the carving or painting is sunk below the level of the surrounding surface and is contained within ' a sharply incised contour line that frames it with a powerful line of light and shade'.
sfumato
The technique is a fine shading meant to produce a soft transition between colours and tones, in order to achieve a more believable image. It is most often used by making subtle gradations that do not include lines or borders, from areas of light to areas of dark. The technique was used not only to give an elusive and illusionistic rendering of the human face but also to create rich atmospheric effects. Leonardo da Vinci described the technique as blending colours, without the use of lines or borders "in the manner of smoke". Britinnaca.com
(My artist husband's own personal term for this is dissonance.)
I'm assuming that you mean effects like "The Death of Marat"? Or do you mean a style like a true unfinished painting, like "Unfinished Portrait of President Franklin Delano Roosevelt"?
This may be only related in part, but in comics and graphic narrative Scott McCloud describes the contrast between high and low detail as the "masking effect."
In it, the figures and ground are rendered at dramatically different levels of detail -- usually with the ground in higher detail than the figure. As examples, McCloud cites the Belgian "clear-line" style of Herge, work on Cerebus by Sim and Gerhard, the Disney animated film house style, and Japanese manga of the 1980s. See Understanding Comics pp42-44.
"The origins of this practice come from antiquity and the philosophies of Plato. Platonic philosophy states that any work of art, or otherwise, never completely resembles its heavenly counterpart. The act of leaving a work unfinished is sometimes an homage to this (Wiki, non-finito)."
Also see this article, the author goes in depth with the history, and particular artists of the renaissance.
It was also used by portraitists as a courtesy to their subject. The artist's complement to his subject; in effect saying that their beauty or honor could not be captured, thus it is embodied in what cannot be expressed. The unfinished portion.
Artistic style (non-finito).
