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12 pages, 907 KB

Open AccessArticle

Evaluation of Trabecular Microstructure of Cancellous Bone Using Quarter-Detector Computed Tomography

by Hiroaki Hasegawa, Nobuhito Nango and Masafumi Machida

Diagnostics 2023, 13(7), 1240; https://doi.org/10.3390/diagnostics13071240 - 25 Mar 2023

Cited by 2 | Viewed by 3833

Quarter-detector computed tomography (QDCT) is an ultra-high-spatial-resolution imaging technique. This study aimed to verify the validity of trabecular structure evaluation using a QDCT scanner in the diagnosis of osteoporosis. We used a cancellous bone specimen image of the second lumbar vertebrae of an adult male with moderate osteoporosis. To obtain QDCT images, we created a three-dimensional model from micro-CT images of the specimen. Statistical analysis was performed on the relationship between micro-CT and QDCT imaging modalities. The differences between micro-CT and QDCT were assessed based on their significance with respect to the calculated mean measurements using the Mann–Whitney test. Single regression analysis was performed using linear regression, with micro-CT and QDCT as the explanatory and objective variables, respectively, to determine the relationship of the measured values between the two modalities. By applying the necessary correction to the micro-CT measured values, it is possible to perform an analysis equivalent to micro-CT, which offers higher spatial resolution than QDCT. We found evidence that if QDCT can be used, trabecular structure evaluation may contribute to image diagnosis to evaluate practical bone fragility. Full article

(This article belongs to the Section Medical Imaging and Theranostics)

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21 pages, 5282 KB

Open AccessArticle

A Novel Separable Scheme for Encryption and Reversible Data Hiding

by Pei Chen, Yang Lei, Ke Niu and Xiaoyuan Yang

Electronics 2022, 11(21), 3505; https://doi.org/10.3390/electronics11213505 - 28 Oct 2022

Cited by 14 | Viewed by 2412

Abstract

With the increasing emphasis on security and privacy, video in the cloud sometimes needs to be stored and processed in an encrypted format. To facilitate the indexing and tampering detection of encrypted videos, data hiding is performed in encrypted videos. This paper proposes a novel separable scheme for encryption and reversible data hiding. In terms of encryption method, intra-prediction mode and motion vector difference are encrypted by XOR encryption, and quantized discrete cosine transform block is permutated based on logistic chaotic mapping. In terms of the reversible data hiding algorithm, difference expansion is applied in encrypted video for the first time in this paper. The encryption method and the data hiding algorithm are separable, and the embedded information can be accurately extracted in both encrypted video bitstream and decrypted video bitstream. The experimental results show that the proposed encryption method can resist sketch attack and has higher security than other schemes, keeping the bit rate unchanged. The embedding algorithm used in the proposed scheme can provide higher capacity in the video with lower quantization parameter and good visual quality of the labeled decrypted video, maintaining low bit rate variation. The video encryption and the reversible data hiding are separable and the scheme can be applied in more scenarios. Full article

(This article belongs to the Topic Computer Vision and Image Processing)

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13 pages, 1489 KB

Open AccessArticle

Reversible Data Hiding Scheme Based on Coefficient Pair Mapping for Videos H.264/AVC without Distortion Drift

by Thai-Son Nguyen

Symmetry 2022, 14(9), 1768; https://doi.org/10.3390/sym14091768 - 25 Aug 2022

Cited by 11 | Viewed by 2274

Abstract

Reversible data hiding is a technique for embedding secret data into a cover media. Such technique has the ability to recover marked cover media to its original version after extracting the secret data. In this paper, a new reversible data hiding algorithm for videos H.264/AVC is proposed to improve the embedding capacity while the distortion drift is prevented. To embed the secret data into videos H.264/AVC without any intra-frame distortion drift, in our proposed scheme, the relationship of QDCT coefficients is explored. Then, a coefficient pair mapping mechanism in 2D histogram is introduced for embedding data. The experimental results demonstrated that the proposed scheme obtains reversibility. The proposed scheme prevents intra-frame distortion drift on the marked videos. In addition, the embedding capacity of the proposed scheme is superior to that of existing schemes while guaranteeing the high visual quality of marked videos. Full article

(This article belongs to the Section A: Computer Science)

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13 pages, 618 KB

Open AccessArticle

Genuine Reversible Data Hiding Technique for H.264 Bitstream Using Multi-Dimensional Histogram Shifting Technology on QDCT Coefficients

by Jinwoo Kang, Hyunjung Kim and Sang-ug Kang

Appl. Sci. 2020, 10(18), 6410; https://doi.org/10.3390/app10186410 - 14 Sep 2020

Cited by 5 | Viewed by 3003

Abstract

Video has become the most important medium for communication among people. Video has become the most important medium for communication among people. Therefore, reversible data hiding technologies for video have been developed so that information can be hidden in the video without damaging the original video in order to be used in the copyright protection and distribution field of video. This paper proposes a practical and genuine reversible data hiding method by using a multi-dimensional histogram shifting scheme on QDCT coefficients in the H.264/AVC bitstream. The proposed method defines the vacant histogram bins as a set of n-dimensional vectors and finds the optimal vector space, which gives the best performance, in a 4 × 4 QDCT block. In addition, the secret message is mapped to the optimal vector space, which is equivalent to embedding the information into the QDCT block. The simulation results show that the data hiding efficiency is the highest among the compared five existing methods. In addition, the image distortion and maximum payload capacity are measured quite high. Full article

(This article belongs to the Special Issue Emerging Information Technologies for Next Generation Communications and Networks including Selected Papers from ICGHIT 2020.)

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