A 2D color barcode layout is disclosed. The barcode includes a 2D array of data cells, four corner locators, and border reference cells forming four borders between the corner locators that substantially surround the array of data cells. Each data cell and border reference cell has one of four primary colors (e.g. CMYK). Most border reference cells have the same size as the data cells, except for yellow ones which are longer. The border reference cells form a repeating color sequence along the borders, and are used during decoding to calculate (1) the channel offset (a spatial offset) of each primary color at different locations along the borders and (2) the reference (average) color values of each primary color. During decoding, the color values of each data cell is measured while taking into account channel offset which is calculated by interpolating the channel offset of the border reference cells.