A H.265/HEVC Fine-Grained ROI Video Encryption Algorithm Based on Coding Unit and Prompt Segmentation

2026-04-09

AI Summary

This study addresses the limitations of existing tile-based region-of-interest (ROI) video encryption methods, which suffer from coarse granularity and imprecise localization, thereby failing to meet the stringent requirements for high-precision protection in domains such as healthcare and defense. To overcome these challenges, this work proposes a novel fine-grained selective encryption algorithm based on coding units (CUs) and prompt-guided segmentation, achieving ROI encryption precision at the 8×8 CU level for the first time. Precise ROI localization is enabled through prompt segmentation, while a diffusion-isolation strategy—combining multi-syntax-element perturbation with constraints on PCM mode and motion vectors—effectively suppresses encryption-induced artifacts. Experimental results demonstrate that the proposed method accurately segments and encrypts target regions, significantly enhancing both encryption precision and practical utility while preserving visual privacy.

Abstract

ROI (Region of Interest) video selective encryption based on H.265/HEVC is a technology that protects the sensitive regions of videos by perturbing the syntax elements associated with target areas. However, existing methods typically adopt Tile (with a relatively large size) as the minimum encryption unit, which suffers from problems such as inaccurate encryption regions and low encryption precision. This low-precision encryption makes them difficult to apply in sensitive fields such as medicine, military, and remote sensing. In order to address the aforementioned problem, this paper proposes a fine-grained ROI video selective encryption algorithm based on Coding Units (CUs) and prompt segmentation. First, to achieve a more precise ROI acquisition, we present a novel ROI mapping approach based on prompt segmentation. This approach enables precise mapping of ROIs to small $8\times8$ CU levels, significantly enhancing the precision of encrypted regions. Second, we propose a selective encryption scheme based on multiple syntax elements, which distorts syntax elements within high-precision ROI to effectively safeguard ROI security. Finally, we design a diffusion isolation based on Pulse Code Modulation (PCM) mode and MV restriction, applying PCM mode and MV restriction strategy to the affected CU to address encryption diffusion during prediction. The above three strategies break the inherent mechanism of using Tiles in existing ROI encryption and push the fine-grained level of ROI video encryption to the minimum $8\times8$ CU precision. The experimental results demonstrate that the proposed algorithm can accurately segment ROI regions, effectively perturb pixels within these regions, and eliminate the diffusion artifacts introduced by encryption. The method exhibits great potential for application in medical imaging, military surveillance, and remote areas.

Problem

• ROI video encryption
• H.265/HEVC
• fine-grained encryption
• Coding Unit
• encryption precision

Innovation

• fine-grained encryption
• ROI mapping
• Coding Unit (CU)
• prompt segmentation
• encryption diffusion isolation