Look-up table based multiple watermarking with minimum distortion

Several quantization based watermarking techniques have been used for data hiding in which a watermark is embedded into the source image by quantizing the image coefficients and on the receiver end these coefficients are dequantized and watermarks are extracted from the watermarked image. In all these techniques after embedding the watermark some perceptual degradation is observed in the visual quality of the image. In quantization based embedding method all of the quantized values are equally separated in the range of the possible values and are alternately assigned to messages "1" and "0." The probabilities of watermark errors caused by malicious tampering and incidental distortion will be, respectively, maximized in this scheme. To enhance the security a lookup table (LUT) is generated first for embedding the binary watermark in which the quantization intervals are randomly assigned to "1" and "0" and then its robustness is analyzed. From the experimental results it is analyzed that LUT based embedding proves to be highly robust in comparison to other quantization based embedding method.