Patent ID: 7619607

Claim:
A method for creating a pattern on a liquid crystal display (LCD) and decoding position data from the pattern, the method comprising steps of: defining a size of the pattern on an LCD by a grid with a plurality of pixels, each pixel having sub-pixels with an adjustable intensity value; determining an area of the grid for embedding position data, wherein the position data provides an indication of position relative to the LCD and wherein the position data is comprised of a plurality of dots; and embedding the position data in the determined area of the grid by: for each dot associated with the position data, selecting one of the plurality of pixels of the grid corresponding to the position of the dot of the pattern, selecting a sub-pixel of the selected pixel, and adjusting the intensity value of the selected sub-pixel to indicate its correspondence with the dot wherein the adjusted intensity value of the selected sub-pixel is based on an underlying image displayed on the LCD; receiving a captured image: decoding position data from the pattern, wherein decoding position data includes, processing the captured image to output an extracted bit stream by, preprocessing the captured image to determine pixels corresponding to LCD pixel grids associated with the embedded interaction code pattern, wherein preprocessing includes: separating pixels that lie on edges and vertexes of the LCD pixel grids as a first mask, binary eroding the first mask to obtain a second mask, the second mask including fewer pixels than the first mask, separating connected regions of the second mask in accordance with a first threshold to obtain a third mask and a fourth mask, binary eroding the fourth mask to obtain a fifth mask, defining a second threshold corresponding to a region of the fifth mask, defining a sixth mask as pixels that belong to the regions of the fifth mask, and merging the third and the sixth masks to define the LCD pixel grids, defining the LCD pixel grids based upon the pixels, recognizing the embedded interaction code pattern from the LCD pixel grids, extracting a bit stream of embedded interaction code bits based upon the recognized embedded interaction code pattern to obtain the extracted bit stream; decoding position data from the extracted bit stream, and determining a position of the captured image relative to the LCD based upon the decoded position data so that the position of an image captured from the LCD can be determined relative to the LCD based on the adjusted intensity values of the sub-pixels.