1. A computer-implemented method comprising: obtaining blocks that each include multiple pixels, pixels of a first block being separated from pixels of a neighboring second block by a block boundary; selecting a correction mode from amongst first and second correction modes using information from the first block and information from the second block; adjusting only one pixel of each of the first and second blocks if the first correction mode is selected; and adjusting at least three pixels of each of the first and second blocks if the second correction mode is selected.