DM-LIKE DIFFERENTIAL CHAIN CODE FOR HANDWRITING AND LINE GRAPHICS

A new type of differential chain code, referred to as delta-modulation -like (DM-like) differential chain coding (DM-DCC) which resembles tra ditional delta modulation proposed coding handwriting and graphics. Si nce DM-DCC uses only one bit in the encoded vector chain, it achieves the highest coding efficiency when compared with differential chain co ding (DCC) and standard chain coding (SCC) in terms of coding rate and encoded file size. DM-DCC has a more uniform data syntax than DCC, an d when combined with a robust coding technique DM-DCC is more error re silient than DCC and SCC, Similarly to conventional DM used for one-di mensional waveform coding, however. DM-DCC introduces granular distort ion for slowly curving traces and curvature overload distortion for ra pidly curving traces. The additional quantisation distortion due to DM -DCC with respect to DCC is calculated. Postprocessing smoothing and a daptive coding techniques are applied in DM-DCC to reduce quantisation distortions, resulting in much improved subjective dynamographical im age quality.