GUEST EDITORIAL Special Issue on Digital Holographic 3D Imaging: Capture, Display, and Evaluation Holography has been fascinating people for almost 70 years (since Gabor's invention in 1947) as a true three‐ dimensional (3D) imaging technology that can replicate 3D scenes in free space. Holography has also led to important developments in physics and technology as manifested by fundamental ideas proposed by renowned scientists and holographers, such as Emmeth Lieth (off‐axis holography), Yuri Denisyuk (reflection holography), Stephen Benton (rainbow holography), and Adolf Lohmann (computer‐gen- erated holograms). Their ideas have been established as essential concepts and have advanced considerably the field of optical and digital holography during the past fifty years. The 21st century is the age of digital technology and tre- mendous progress in optoelectronics and micro/nanotech- nology has been accomplished. This progress has opened the doors for true holographic applications in important areas such as holographic 3D displays with photorealistic visualization, 3D quantitative imaging in biomedicine, opti- cal metrology using digital holographic interferometry, microscopy, and tomography. Successful applications and true holographic products in the market have advanced holography to a level at which standards setting organiza- tions must be involved to guarantee interoperability between devices and applications. In this special issue, we have selected several publica- tions that represent the current state‐of‐the‐art in digital holographic imaging covering new optoelectronic devices/ materials, and their applications and full technology chains from the capture/generation of content, to processing, manipulation, and compression, including novel displays and holographic microscopes, tomographs, and the quantita- tive evaluation of complex amplitude data. The invited paper “Recent advances on metasurface holo- gram technologies” by Gun‐Yeal Lee, Jangwoon Sung, and Byoungho Lee, outlines the recent progress in metasurface holograms of artificially fabricated subwavelength structures. These holograms have been considered as novel holographic devices that have shown an unprecedented ability to control electromagnetic waves. Various metasurface holograms, such as complex amplitude, multicolor, polarization‐multiplexed and active holograms, have been compared in terms of features, benefits, and remaining challenges. Additionally, the authors discuss their roles as elements in the introduction and use of high‐performance wavefront engineering in holo- graphic displays and in many other photonics devices. In the second paper entitled “Evolution of spatial light modulator for high‐definition digital holography” by Ji Hun Choi et al., a report is presented on the fabrication methods, device performance, and holographic results of liquid crystal spatial light modulators fabricated on glass substrate (SLMoG) as a good alternative to liquid crystals on silicon (LCoS) SLM. A series of SLMoG with different pixel pitches (3 μm, 7 μm, and 20 μm) have been produced and tested with a special focus on a pixel size of 3 μm that repre- sents currently the smallest pixel pitch of SLMoGs for digital holograms. It is shown that this provides good image quality and an approximate horizontal diffraction angle of 10° for light with a wavelength of 532 nm. The paper “Reducing speckle artifacts in digital hologra- phy by the use of programmable filtration” by Yongjun Lim et al. addresses the important problem of speckle arti- facts reduction in binary‐type holographic displays. The authors propose the adoption of programmable filtration in a general 4‐f optical configuration to selectively filter signal spectral components in the frequency domain of a viewing‐ window‐based holographic display. The method is utilized to effectively reduce the speckles during reconstruction of point‐cloud–based computer‐generated holograms. Another important challenge in holographic displays is to deliver an enlarged viewing zone. One of the recently proposed solutions to achieve this is the rainbow holo- graphic display that allows the reconstruction of large 3D orthoscopic objects. However, the display provides views where color and resolution are changing with the move- ment of an observer's eye, thereby influencing his visual perception. The fourth paper on “Visual perception of Fourier rainbow holographic display” by Hyon‐Gon Choo, Maksymilian Chli- pala, and Tomasz Kozacki, addresses this problem using the Wigner Distribution. The view‐dependent appearance of the image—including the multispectral field‐of‐view, viewing zone, and the resolution of holographic view—is investigated ---------------------------------------------------------------------------------------------------------------------------------------------------------------------- This is an Open Access article distributed under the term of Korea Open Government License (KOGL) Type 4: Source Indication + Commercial Use Prohibition + Change Prohibition (http://www.kogl.or.kr/info/licenseTypeEn.do). 1225-6463/$ © 2019 ETRI DOI: 10.4218/etr2.12168 ETRI Journal. 2019;41(1):7–9. wileyonlinelibrary.com/journal/etrij | 7