Data embedding and extraction techniques for documents

摘要: Improved data embedding and extracting techniques provide a way to embed extract messages in text sections of documents during copying. Extracted pixels are grouped together form lines the document. From this formation, document layout is constructed that used message pixels. Each line partitioned into blocks, those which contain certain threshold percentage identified as valid. valid block one bit information by labeling with predetermined color. The bits blocks particular done column-wise raster order. Only character (which may be comprised multiple bits) embedded line, although times same if there enough blocks. Extracting so involves forming first representation classified locate embedded, second identify These two representations compared clusters color-labeled each determine location message. sorted accordance order converted sequence decoded line.