1. A method for detecting an optical information, the method comprising: detecting, at an optical detection unit coupled to an optical information processor, an image of a source data page coded with balanced codewords by the use of 1:N (where N is 1.33 or 1.5) excessive detection pixels, wherein the optical detection unit comprises N×N detection pixels per 1×1 data pixel of the source data page for detecting optical information by using the 1:N excessive detection pixels, and each excessive detection pixel detects the optical information using a detection region having a vertical width or a horizontal width smaller by a half than the vertical width or the horizontal width of each of the corresponding excessive detection pixel, wherein the detection region is configured to detect the image and the detection region and the corresponding excessive detection pixel are made of pixel sensors comprising one of complementary metal-oxide semiconductor (CMOS) pixels or charge-coupled device (CCD) pixels, and wherein the detection region locates at an upper, a center, or a lower portion of each of the corresponding excessive detection pixel; determining, at the optical information processor, a distribution pattern of valid detection pixels and invalid detection pixels to be corrected in the detected image by the use of a light intensity distribution of the detected image; and dividing the detected image into balanced codeword detecting areas corresponding to the balanced codewords and sampling data of the balanced codeword detecting areas by the use of the determined distribution pattern and an optical distribution characteristic of the balanced codewords.