A computer system for processing a viewport within an image arranged as a matrix of tiles from a container file is disclosed herein. The computer system includes one or more processors configured to: (a) receive a request to read data of the viewport starting from a point of origin of the viewport, the viewport having a pixel width and a pixel height, the viewport being a portion of an image that is stored in a record within the file container; (b) compute column numbers or row numbers, or both, of the tiles containing the viewport; and (c) read in parallel or asynchronously each row or each column of tiles containing the viewport.