Convergence
When lines or other elements draw closer together, they can be used to lead our eyes to a focal point.
Frida Kahlo’s Self-Portrait with Medallion (1948) shows the artist wearing a traditional Mexican Tehuana headdress.
The collar flattens the space so that the artist seems to emerge through the frame.
Emphasis is created by the folds in the material. These form a circle of converging lines that lead our eyes to Kahlo's features.
There are no physical lines that converge in The Adoration of the Shepherds (Guido Reni, 1640) but the direction in which the figures are looking suggests converging eye-lines that lead to the baby in the manger.
Contrasting tone adds more emphasis. The baby is brightly lit while the surrounding figures grow darker as they move away from this highlighted point. The background is very dark and fades away as a result.