Final answer:
The line separating two textures in graduated form in an artwork is known as the figure-ground relationship. Techniques such as hatching and good continuation play significant roles in defining this relationship, impacting how we perceive figure (object) from ground (background).
Step-by-step explanation:
The line that visually separates the two textures in graduated form on an artwork is referred to as the figure-ground relationship. This concept is essential in art as it helps to define forms within a composition, distinguishing what sits on top (figure) from the background (ground). For example, in the work of Henri Matisse, the white lines defining form in a red field are not painted over the red; rather, they are the canvas below, demonstrating a classic figure-ground relationship.
Different techniques such as hatching are used to enhance the illusion of texture and depth within the separated areas. With hatching, closely spaced lines create a sense of shadowing and three-dimensionality, as seen in the shadow on the left side of a hat within a drawing. This technique contributes to separating one area of texture from another subtly, where the lines indicating shadows enhance the figure-ground separation.
Additionally, good continuation plays a role in how we perceive lines within a composition, suggesting that overlapping lines tend to be seen as continuous rather than as separate intersecting segments, further influencing the perception of figure and ground in art.