Apparatus and a method for processing image data where row data is received corresponding to a target row of pixels and to one or more reference rows of pixels. A target row average is generated based on the target row data and a reference row average is generated for each of the one or more reference rows based on each reference row's respective row data. A row correction value is generated based on the target row average of the target row and the reference row average of the one or more reference rows. Corrected target row data is generated by applying the row correction value to the target row data.