A method of rendering an image using a number of threads, by receiving edge data for the image comprising edges identified by indices, each edge having edge scan line crossing coordinates, arranging the coordinates into partitions indexed by the indices to form a data structure that is randomly accessible by a coordinate of a portion of the image; each partition comprising a list of edge scan line crossing coordinates associated with an edge that is identified by the edge index indexing the partition, and rendering the portions of the image concurrently, using corresponding threads by identifying, by randomly accessing a partition in the indexing data structure using a coordinate of said portion in the image, at least one edge in the indexing data structure associated with said portion of the image.