说明：  purpose simulates embedding and detection of watermark in random noise using QIM (quantization index modulation), uses non-linear scaling compile gcc -g -o nlqim nlqim.c -lm
(purpose simulates embedding and detectio n of watermark in random noise using QIM (quanti index modulation. 5), uses non-linear scaling compile gcc-g-o nlqim nlqim.c- lm)