1. A computer-implemented method for detecting a table grid in a received digital document and extracting the table grid from the received digital document, comprising: extracting connected components from the received digital document to identify table grid candidates; extracting grid line components from said table grid candidates; validating the grid line components as belonging to a table grid; separating noise, graphics, handwriting, and/or touching text from validated grid line components by initializing the table grid by merging all inverse cell components into one single connected component, where an inverse cell component comprises a white text component on a dark background, and merging all horizontal and vertical black connected components that are connected with the table grid to the table grid to identify short grid lines shorter than a threshold and all remaining connected components that are not connected with an inverse cell component; and extracting regular cells from said validated grid line components.