One way of extra robustness in watermarking is to partition a logo into parts and insert them with unequal embedding strengths. In this paper, first, three major requirements for logo partitioning are introduced and then a modified version of spatial scalability as a proper partitioning method is suggested. The proposed idea is general and can be applied to any logo watermarking technique, but as an example it is tested with a DCT-based Quantization Index Modulation (QIM) image watermarking scheme. The robustness of the proposed layered logo watermarking method is evaluated against the conventional single-layer approach with various embedded logos and attacks. The simulation results confirm the superiority of the proposed layered watermarking against the traditional single layer scheme.
Image Watermarking; Layered Logo Watermarking; Base and Enhancement layers; Spatial Scalability.