Top-down refers to a mode of generation or processing in which the outcome is determined less by local interactions among lower-level elements and more by higher-level frameworks, externally supplied controls, or preset constraints. In the provided context, pixel sorting is described as relatively top-down because pixels are rearranged according to upper-level processing conditions such as the processing range, direction, and sort key. Distortion is also considered top-down when it depends strongly on externally given coordinate control, including noise fields, masks, vector fields, control textures, and time functions.
The key point is that top-down does not simply mean “commanded from above.” Rather, it describes a structure in which the generative process depends on an already defined framework or mapping, instead of emerging primarily from the accumulation of local rules. The context also notes that distortion can include bottom-up characteristics when it relies heavily on local reference to previous states or feedback. For this reason, top-down and bottom-up should be understood as tendencies along a spectrum rather than as strictly separate categories.