A signal processor selects an element from a rendition of a signal at a first level of quality to upsample into multiple elements of a rendition of the signal at a second (higher) level of quality. The signal processor produces a metric based on settings of elements in a vicinity of the selected element in the rendition of the signal at the first level of quality. The metric defines a boundary between a first set of elements in a vicinity of the selected element and a second set of elements in a vicinity of the selected element. The signal processor utilizes the metric to calculate settings for the multiple elements in the signal at the second level of quality. A location and orientation of the boundary with respect to the selected element depends on the settings of elements in the vicinity of the selected element.