1. A system for coding, the system comprising: a processor configured to prepare video compression data based on source pictures, the preparing including: partitioning the source pictures into coding units; generating transform units, each transform unit being a transform array including transform coefficients assigned as entries to y-x locations of the transform array, based on residual measures associated with the coding units; and for each generated transform unit, processing the generated transform unit by: generating a significance map, having a significance map array with y-x locations corresponding to the y-x locations of the transform array of the generated transform unit; when the transform array is above a defined size: scanning, utilizing a zigzag scanning pattern, a plurality of significance map elements in the significance map array; and determining a context model for coding a value associated with each of the plurality of significance map elements based on a respective value of at least one neighbor significance map element of the significance map element in the significance map array, the at least one neighbor significance map element located before a position of a current significance map element within a path defined by the zigzag scanning pattern; and when the transform array is at or below the defined size: determining the context model for coding the value associated with each of the plurality of significance map elements using a fixed criteria model for each position in the significance map array without reference to other significance map elements in the significance map array.