Mo phong Watermark\dct2_embed_mod.m ..................\dct2_recover_mod.m ..................\dct2_watermarked_mod.bmp ..................\pn_period.m ..................\pn_test.m ..................\psnr.m ..................\_copyright.bmp ..................\_key.bmp ..................\_lena_std_bw.bmp Mo phong Watermark