Seungcheol Choi

Network development has made it easier to access multimedia material and to change it by allowing the collection, modification, and transmission of digital data. Additionally, this has led to a rise in malicious use, including unauthorized data distribution and copying. As the quantity of evil activities increases, security issues such as unauthorized use and image forgery are rising. While security solutions for JPEG-1 images are widely available, there remains a significant gap in protection for JPEG 2000 images. In this paper, we propose a new watermark-based forgery detection method to comply with the JPEG Privacy and Security standards and to authenticate JPEG 2000 image integrity in the discrete wavelet transform (DWT) domain. The method proposed divides JPEG 2000 images into groups of blocks (GOBs) within the DWT domain. The watermark is generated by collaborating with the neighboring GOBs and is embedded in the GOBs. It enables you to respond to the collage attack. Experimental results using various sample images show the superiority of the proposed method, showing negligible visual differences between the original and watermarked JPEG 2000 images.

Most people watch short-form content, especially when viewing it on their smartphones. While short-form content is widely used for entertainment, it is also for essential information sharing with broad audiences. The importance of short-form content is self-evident, as Facebook and YouTube have introduced Facebook Reels and YouTube Shorts, respectively. The rapid, widespread adoption of short-form content indicates the need for a new international standard to ensure the interoperability of broad content and content creation tools. This article overviews a new international standard development effort in the Joint Photographic Experts Group (JPEG) in ISO/IEC JTC1/WG1 to create JPEG Snack (ISO/IEC 19566-8) to enable image-rich content creation and sharing. JPEG Snack images, audio, videos, and captions are embedded in the standard JPEG-1 (ISO/IEC 10918-1) image file. The JPEG Snack file comprises two components: i) a default JPEG-1 image and ii) an ISO base media file format (ISOMBFF (ISO/IEC 14496-12)) box-based file extension. The JPEG-1 image portion makes the file compatible with existing JPEG viewers for preview and user navigation, while enhanced JPEG Snack viewers can display the rich image/audio/video/caption short-form content. The article presents essential features of the JPEG Snack and its comparison with JPEG-linked media format (JLINK (ISO/IEC 19566-7)) and JPEG 360 (ISO/IEC 19566-6). It also presents the pros and cons of JPEG Snack over high-efficiency image file format (HEIF (ISO/IEC 23008-12)).

The Joint Picture Expert Group (JPEG) committee has been standardizing next-generation image compression, called JPEG XL, to meet the specific needs for a responsive web, wide color gamut, and high dynamic range. JPEG XL supports lossy and lossless compression. A variable-sized discrete cosine transform (DCT) block is used for lossy compression. A block partitioning method is regarded as a critical function for the performance of JPEG XL. The current DCT block partitioning method used in JPEG XL is highly dependent on the compression rate and tends to assign small-sized DCT blocks to homogeneously textured regions (HTRs) having similar or regular patterns. We propose a region-adaptive DCT block partitioning method that assigns larger blocks to the HTR. The proposed method identifies the HTRs by using a combined metric employing a sum-modified Laplacian, zero-crossing, and colorfulness metric for measuring the region homogeneity. Objective, subjective, and visual comparison evaluations with the ten images recommended by the JPEG working group were provided to show the improvement in coding performance. The proposed method shows its superiority in terms of the compression efficiency evaluated using six objective metrics, subjective tests with 15 participants, visual comparison improvements in the HTR, and gains in the execution time.

Imaging devices capable of capturing 360° images were recently released into the market. The spherical images acquired by imaging devices, such as 360° cameras and multiple camera smartphones, are projected onto the 2D image plane to allow the use of the existing image coding standard. The 360° image market is currently dominated by the equirectangular projection format coded by the JPEG image coding standard. Spherical images are characterized by their large size, and they are typically viewed by displaying a default viewport of the entire image first, followed by navigation by the user. Therefore, progressive image coding capable of transmitting the default viewport first is in high demand. However, the progressive image coding methods proposed thus far, such as quality-based and resolution-based progressive coding, do not support the spatial region-based progressiveness necessary to first display the default viewport. This paper proposes a center-to-edge progressive mode for the JPEG image coding standard, which enables transmittance of the discrete cosine transform blocks including the default viewport first by reordering the blocks' scanning path. This progressive mode was designed to maintain all other encoding structures of the JPEG standard, such that use of the already established toolchain of the JPEG is maintained. Results of the test performed with our proposed mode using eleven 360° images in the equirectangular projection format and six objective image quality parameters show that transmission of default viewports is notably faster than existing JPEG modes and negligible effects on JPEG image coding efficiency.

Recently, 360° content has emerged as a new method for offering real-life interaction. Ultra-high resolution 360° content is mapped to the two-dimensional plane to adjust to the input of existing generic coding standards for transmission. Many formats have been proposed, and tremendous work is being done to investigate 360° videos in the Joint Video Exploration Team using projection-based coding. However, the standardization activities for quality assessment of 360° images are limited. In this study, we evaluate the coding performance of various projection formats, including recently-proposed formats adapting to the input of JPEG and JPEG 2000 content. We present an overview of the nine state-of-the-art formats considered in the evaluation. We also propose an evaluation framework for reducing the bias toward the native equi-rectangular (ERP) format. We consider the downsampled ERP image as the ground truth image. Firstly, format conversions are applied to the ERP image. Secondly, each converted image is subjected to the JPEG and JPEG 2000 image coding standards, then decoded and converted back to the downsampled ERP to find the coding gain of each format. The quality metrics designed for 360° content and conventional 2D metrics have been used for both end-to-end distortion measurement and codec level, in two subsampling modes, i.e., YUV (4:2:0 and 4:4:4). Our evaluation results prove that the hybrid equi-angular format and equatorial cylindrical format achieve better coding performance among the compared formats. Our work presents evidence to find the coding gain of these formats over ERP, which is useful for identifying the best image format for a future standard.

Current electronic warfare (EW) systems, along with the rapid development of information and communication technology, are essential elements in the modern battlefield associated with cyberspace. In this study, an efficient evaluation framework is proposed to assess the effectiveness of various types of EW systems that operate in cyberspace, which is recognized as an indispensable factor affecting modern military operations. The proposed method classifies EW systems into primary and sub-categories according to EWs’ types and identifies items for the measurement of the effectiveness of each EW system by considering the characteristics of cyberspace for evaluating the damage caused by cyberattacks. A scenario with an integrated EW system incorporating two or more different types of EW equipment is appropriately provided to confirm the effectiveness of the proposed framework in cyber electromagnetic warfare. The scenario explicates an example of assessing the effectiveness of EW systems under cyberattacks. Finally, the proposed method is demonstrated sufficiently by assessing the effectiveness of the EW systems using the scenario.

Recently, the use of virtual reality has been spreading rapidly in many industrial fields, such as games and entertainment, and 360° contents are widely used in various applications of the virtual reality (VR) market. The 360° contents create a virtual space comparable to real scenes. Coupled with the rapid growth of the 360° image/video field, many projection formats have been developed and published. However, the studies which identify the best format for a variety of applications are still limited. Therefore, it is desirable to evaluate the visual quality of the projection formats used in the current market, and the result of the evaluation can be used as an important consideration capable of providing 360° VR service of better quality. Here, we propose a methodology for the subjective test and briefly present ten 360° projection formats used in our experiment. The proposed methodology for the subjective test uses a combination of the Degradation Category Rating (DCR) and Pair Comparison methods. We performed the subjective test with 15 participants for each test step, the experimental set-up for which followed the proposed methodology. The results show that the equirectangular projection format (best known and widely used format in most commercial products) did not give the highest quality. Hybrid equiangular cubemap and equatorial cylindrical projection gave the best quality compared with the other eight formats. Based on the results of the DCR, it is noted that different monitors (size and resolution) do not affect the ranking of 360° image projection formats. Our work presents the ranking of ten published projection formats which is useful for identifying the best format for a future 360° image standard.

JPEG is the most common image format in smartphones, computers, or digital cameras. Because numerous JPEG images are easily shared and distributed, there are privacy and security concerns for these images. Hence, the JPEG committee has started a standardization called JPEG privacy and security to resolve these issues. The forgery detection of a JPEG image is the key objective of JPEG privacy and security. In this paper, we propose a novel forgery detection method that is watermark-based, for authenticating JPEG image integrity in the discrete cosine transform (DCT) domain. The proposed method aims at 100% detection accuracy for typical forgeries on JPEG image DCT blocks and to counter a well-known forgery attack called collage attack. For this purpose, the method splits the host image into a group of blocks (GOB). A watermark is generated by collaborating with the neighboring GOBs and is embedded into the GOBs. The experimental results using various sample images show the superiority of the proposed method, exhibiting a negligible visual difference between the original and watermarked JPEG images.

Displays capable of representing high-dynamic range (HDR) images were recently released in the digital consumer electronics market, and consumers have become increasingly interested in HDR images. However, the majority of today's digital imaging devices are still low dynamic range (LDR) using an 8-bit representation for each RGB color components; hence, a backward-compatible HDR image format with an existing LDR-based imaging environment is required. Accordingly, JPEG XT, a new HDR image coding standard providing JPEG backward compatibility was established by the JPEG committee based on the market needs. JPEG XT consists of a base and a residual layer. Both layers are independently encoded by a legacy JPEG encoder. Most importantly, the base layer contains a tone-mapped LDR version of the HDR image for compliance with a legacy JPEG decoder. To date, three profiles have been defined for JPEG XT to encode HDR images, which are represented using floating-point values. This study proposes a new imagecoding scheme that uses a region adaptive prediction method with modified current specifications on JPEG XT Part 7. The proposed method adaptively predicts the HDR pixel value using a different prediction information for each block based on the ratio between the LDR and HDR blocks, which is invariant to the tone-mapping operator, while the existing JPEG XT profiles globally predict the HDR values using an inverse transformation of the LDR values. Experimental results using various sample images show the superiority of the proposed method in terms of objective and visual evaluations.