A Non-Blind Watermarking Scheme for Gray Scale Images in Discrete Wavelet Transform Domain using Two Subbands

TL;DR

This paper presents a non-blind digital watermarking method for gray scale images using wavelet transform and SPIHT compression, achieving high robustness and imperceptibility against various image processing attacks.

Contribution

It introduces a novel watermark embedding technique in wavelet subbands based on significant coefficients and noise visibility, enhancing robustness and imperceptibility.

Findings

High robustness against noise, filtering, and compression attacks

Effective imperceptibility with minimal visual distortion

Superior performance compared to existing methods

Abstract

Digital watermarking is the process to hide digital pattern directly into a digital content. Digital watermarking techniques are used to address digital rights management, protect information and conceal secrets. An invisible non-blind watermarking approach for gray scale images is proposed in this paper. The host image is decomposed into 3-levels using Discrete Wavelet Transform. Based on the parent-child relationship between the wavelet coefficients the Set Partitioning in Hierarchical Trees (SPIHT) compression algorithm is performed on the LH3, LH2, HL3 and HL2 subbands to find out the significant coefficients. The most significant coefficients of LH2 and HL2 bands are selected to embed a binary watermark image. The selected significant coefficients are modulated using Noise Visibility Function, which is considered as the best strength to ensure better imperceptibility. The approach is tested against various image processing attacks such as addition of noise, filtering, cropping, JPEG compression, histogram equalization and contrast adjustment. The experimental results reveal the high effectiveness of the method.