# Holographic Projection Technology in the Field of Digital Media Art

Authors: Yulong Liu; Shan Wu; Qi Xu; Hubin Liu
Journal: Wireless Communications and Mobile Computing
 (2021)

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## Abstract

The advent of the digital age has given new forms and new connotations to artistic creation, and more and more digital media technologies have entered the stage of artistic creation and exhibitions. At present, holographic projection technology has become a hot application technology in the field of digital media art. The purpose of this paper is to explore the technical principles of holographic projection technology and its application in the field of digital media art, so as to provide suggestions for the application and promotion of holographic projection technology and the development and innovation of digital media art. First of all, this article understands the technical principles of holographic projection and its application status in various fields, especially in the field of digital media art, through relevant literature research. Then, this article introduces the digital holographic technology, virtual imaging technology, and computer simulation technology used in the realization of holographic projection technology. Then, based on the advantages of holographic projection technology in three-dimensional image recording and reproduction, this paper proposes to introduce holographic projection technology to digital art museums, digital art exhibitions, and other digital media art applications and to study the effect of holographic projection technology on art through simulation experiments, the effect of recording and reproducing the image of the work. Finally, the three-dimensional reconstruction image of the digital holographic projection experiment on the artwork is compared with the simulated image of the Contour GT profiler to verify the feasibility of applying the holographic projection technology to art exhibitions and the effect of three-dimensional image recording and reproduction. Research shows that the holographic projection technology can achieve 93.34% of the simulation effect of recording and reproducing 3D images of artworks. It is also found that 59.86% of the audience who pay attention to the art experience strongly support the application of holographic projection technology in digital media art fields such as digital art gallery. This fully proves the feasibility of applying holographic projection technology to digital art exhibitions and provides a full range of artistic experience for audiences who cannot be present.


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## Body

## 1. Introduction

### 1.1. Background and Significance

With the continuous development of material living standards, people’s love and pursuit of art are also increasing. However, traditional forms of artistic creation and communication can no longer meet the needs of art pursuers who are restricted by time and space and cannot be present in person. The development of digital media technology provides a new perspective for artistic creation and communication. Digital media art is not a short-lived emerging art form. As early as the 19th century, scholars have put forward the concept of the interactive integration of technology and art through computers [1]. With the development of digital technology, this art form plays an increasingly important role in the development of the art field. The most significant example of the development of digital media art is the application of digital technology in film and television animation, such as the magnificent shipwreck scene in “Titanic,” the reproduction of extinct species in “Jurassic Park,” and the scene production of today’s 3D animation. [2]. Unlike digital media art with a long history of development, holographic projection technology is a novel digital virtual technology [3]. Holographic projection technology breaks the traditional image recording and presentation form, combining 3D technology and holographic technology, not only can record and reproduce three-dimensional images with higher precision, but also can realize the correction through digital holographic microscopy technology and three-dimensional image traceability reconstruction, microscopic observation of objects and replay of missing images [4]. Therefore, holographic projection technology has important applications in holographic microscopic observation of biology, chemistry, and other fields such as image processing in physics and mathematics [5]. However, because the art field pays more attention to immersive art experience and specific and subtle artistic representations and the application of holographic projection technology in some fields is not yet mature, the application of holographic projection technology in the art field has not been deepened.


### 1.2. Related Research at Home and Abroad

Since the introduction of holographic projection technology, scholars from all walks of life have paid constant attention to and research on holographic projection. Makey et al. obtains Fourier holography by preshaping the wavefront to locally reduce the Fresnel diffraction, which combines complex images with complete depth control, allowing random phases to be included at each depth without changing the specific depth projection of the image at [6]. However, true 3D holographic technology also requires complete depth control and dynamic projection functions, which will be affected by high string interference. Makowski et al. proposed a phase-free random method to make hologram reconstruction with very low noise, so that fine projection can be performed without time integration of subholograms [7]. Research shows that through experiments comparing the depth of focus and imaging resolution of various defocus parameters, it can be concluded that the phase-free random method can effectively improve the extended depth of clear imaging. Jamerson discussed the application of digital media art in mental health treatment through examples of using digital media art and technology in group mental health treatment meetings [8]. Research shows that story art plays an important role in people’s perception and interaction of the world. Therefore, narrative therapy and art therapy combined with digital media art have a significant effect on the research and treatment of people’s mental health. Heydon et al. integrated digital media technology into public art courses, collected data through case studies, and conducted a qualitative thematic analysis of multimodal elements in people’s transferable understanding of digitally enhanced multimodal courses throughout the life cycle [9]. The study found that digital media is mainly used to create digital portfolios, and the corresponding nondigital media text production and text production led by teachers and participants are used as references.In China, holographic projection technology is also a research hotspot in various digital media technology applications. Qu proposed a holographic projection with higher image quality that has a reconstructed image that has twice the spatial resolution of existing holographic projections and can well suppress speckles. Experiments show that this holographic projection can effectively improve the spatial resolution of the projected image without being restricted by the size of the spatial light modulator. Chang et al. proposed an implementation method of speckle reduction based on phase-only computer-generated hologram and lensless holographic projection. Virtual convergent light is applied to the image to ensure that its wavefront is focused on the virtual plane established between the image and the hologram plane [10]. Experiments show that in a compact lensless holographic projection system, this method is effective for simultaneously improving the image quality and image size and the size of the projected image can reach the maximum diffraction bandwidth of the spatial light modulator at a given distance. Wu and Krewer reexamined the process of digital practice in the University of Houston library through digital media technology using data-driven methods and put forward strategic recommendations for library digital practice in terms of workflow, digital resources, and infrastructure [11]. Research has shown that the data-driven strategy of digital media technology can effectively improve the quality and efficiency of digital operations. Liang and Kim combined the theory of expression psychology in the field of art, and studied the application of projection mapping technology and digital media technology in the field of new media art design [12]. It was found that the advanced projection mapping technology can not only show the realistic image reproduction effect of the artwork, but even combine the image reconstruction transformation and color adjustment of the digital media technology to show the artistic effect beyond the original artwork.


### 1.3. Innovations in This Article

This article puts forward the new application research directions of holographic projection technology in digital art museums, digital art exhibitions, and other digital media art fields. This paper uses the holographic image recording method based on Fresnel diffraction and lensless Fourier transform in the holographic projection technology to record the holographic image of the artworks allowed to be displayed in art places such as art museums and galleries [13]; then, through Fresnel approximation reconstruction, convolution reconstruction, and angular spectrum reconstruction, holographic projection reproduction of artworks is realized [14]. For paintings, sculptures, and other specific and microspace artworks, this article uses holographic projection technology combined with holographic microscopy to accurately record the optical wavefront and phase distribution of the images of these works and then uses wavefront reconstruction and holographic microscopy to include tiny features in the image of the artwork inside which is reproduced [15]. The application of holographic projection technology in digital art galleries, digital galleries, and art exhibitions in this article can not only satisfy the immersive art experience of audiences who cannot be present but also present three-dimensional images of artworks including tiny features such as lines and brushstrokes. For art lovers who are concerned about artistic creation, it is an innovative research in the application of holographic projection technology in the field of digital media art.


## 1.1. Background and Significance

With the continuous development of material living standards, people’s love and pursuit of art are also increasing. However, traditional forms of artistic creation and communication can no longer meet the needs of art pursuers who are restricted by time and space and cannot be present in person. The development of digital media technology provides a new perspective for artistic creation and communication. Digital media art is not a short-lived emerging art form. As early as the 19th century, scholars have put forward the concept of the interactive integration of technology and art through computers [1]. With the development of digital technology, this art form plays an increasingly important role in the development of the art field. The most significant example of the development of digital media art is the application of digital technology in film and television animation, such as the magnificent shipwreck scene in “Titanic,” the reproduction of extinct species in “Jurassic Park,” and the scene production of today’s 3D animation. [2]. Unlike digital media art with a long history of development, holographic projection technology is a novel digital virtual technology [3]. Holographic projection technology breaks the traditional image recording and presentation form, combining 3D technology and holographic technology, not only can record and reproduce three-dimensional images with higher precision, but also can realize the correction through digital holographic microscopy technology and three-dimensional image traceability reconstruction, microscopic observation of objects and replay of missing images [4]. Therefore, holographic projection technology has important applications in holographic microscopic observation of biology, chemistry, and other fields such as image processing in physics and mathematics [5]. However, because the art field pays more attention to immersive art experience and specific and subtle artistic representations and the application of holographic projection technology in some fields is not yet mature, the application of holographic projection technology in the art field has not been deepened.


## 1.2. Related Research at Home and Abroad

Since the introduction of holographic projection technology, scholars from all walks of life have paid constant attention to and research on holographic projection. Makey et al. obtains Fourier holography by preshaping the wavefront to locally reduce the Fresnel diffraction, which combines complex images with complete depth control, allowing random phases to be included at each depth without changing the specific depth projection of the image at [6]. However, true 3D holographic technology also requires complete depth control and dynamic projection functions, which will be affected by high string interference. Makowski et al. proposed a phase-free random method to make hologram reconstruction with very low noise, so that fine projection can be performed without time integration of subholograms [7]. Research shows that through experiments comparing the depth of focus and imaging resolution of various defocus parameters, it can be concluded that the phase-free random method can effectively improve the extended depth of clear imaging. Jamerson discussed the application of digital media art in mental health treatment through examples of using digital media art and technology in group mental health treatment meetings [8]. Research shows that story art plays an important role in people’s perception and interaction of the world. Therefore, narrative therapy and art therapy combined with digital media art have a significant effect on the research and treatment of people’s mental health. Heydon et al. integrated digital media technology into public art courses, collected data through case studies, and conducted a qualitative thematic analysis of multimodal elements in people’s transferable understanding of digitally enhanced multimodal courses throughout the life cycle [9]. The study found that digital media is mainly used to create digital portfolios, and the corresponding nondigital media text production and text production led by teachers and participants are used as references.In China, holographic projection technology is also a research hotspot in various digital media technology applications. Qu proposed a holographic projection with higher image quality that has a reconstructed image that has twice the spatial resolution of existing holographic projections and can well suppress speckles. Experiments show that this holographic projection can effectively improve the spatial resolution of the projected image without being restricted by the size of the spatial light modulator. Chang et al. proposed an implementation method of speckle reduction based on phase-only computer-generated hologram and lensless holographic projection. Virtual convergent light is applied to the image to ensure that its wavefront is focused on the virtual plane established between the image and the hologram plane [10]. Experiments show that in a compact lensless holographic projection system, this method is effective for simultaneously improving the image quality and image size and the size of the projected image can reach the maximum diffraction bandwidth of the spatial light modulator at a given distance. Wu and Krewer reexamined the process of digital practice in the University of Houston library through digital media technology using data-driven methods and put forward strategic recommendations for library digital practice in terms of workflow, digital resources, and infrastructure [11]. Research has shown that the data-driven strategy of digital media technology can effectively improve the quality and efficiency of digital operations. Liang and Kim combined the theory of expression psychology in the field of art, and studied the application of projection mapping technology and digital media technology in the field of new media art design [12]. It was found that the advanced projection mapping technology can not only show the realistic image reproduction effect of the artwork, but even combine the image reconstruction transformation and color adjustment of the digital media technology to show the artistic effect beyond the original artwork.


## 1.3. Innovations in This Article

This article puts forward the new application research directions of holographic projection technology in digital art museums, digital art exhibitions, and other digital media art fields. This paper uses the holographic image recording method based on Fresnel diffraction and lensless Fourier transform in the holographic projection technology to record the holographic image of the artworks allowed to be displayed in art places such as art museums and galleries [13]; then, through Fresnel approximation reconstruction, convolution reconstruction, and angular spectrum reconstruction, holographic projection reproduction of artworks is realized [14]. For paintings, sculptures, and other specific and microspace artworks, this article uses holographic projection technology combined with holographic microscopy to accurately record the optical wavefront and phase distribution of the images of these works and then uses wavefront reconstruction and holographic microscopy to include tiny features in the image of the artwork inside which is reproduced [15]. The application of holographic projection technology in digital art galleries, digital galleries, and art exhibitions in this article can not only satisfy the immersive art experience of audiences who cannot be present but also present three-dimensional images of artworks including tiny features such as lines and brushstrokes. For art lovers who are concerned about artistic creation, it is an innovative research in the application of holographic projection technology in the field of digital media art.


## 2. Digital Holographic Projection Technology

### 2.1. Holographic Image Recording and Reproduction of Artworks

For object image recording methods, such as traditional camera shooting and projector projection, most of them are recorded according to the coordinates and pixel distribution of the physical object, and then, the object image is presented to the audience through the corresponding projection magnification equipment [16, 17]. The digital holographic projection uses the principle of virtual imaging to record the wavefront information of the light wave emitted by the object in the holographic projection device through the optical light wave phase and amplitude and then converts the recorded wavefront phase information into light wave intensity information and passes optical the principle of the process of reproduction. At present, the holographic image recording methods used in holographic projection technology mainly include three digital holographic image recording methods: Fresnel diffraction holographic recording, lensless Fourier transform holographic recording, and image surface digital holographic recording [18, 19]. Their main principle is to record based on the optical wavefront information reflected by the object, but the recording methods used are different. The process of wavefront recording is to convert the spatial phase information of the reflected light waves of the recorded object into spatial intensity information through light wave interference, which is also the core principle of optical holography technology. During the wavefront recording process, the information of the object light wave Ox,y and the reference light wave Rx,y will be recorded. They can be recorded in the following formats:
(1)Ox,y=ox,y⋅ejφx,y,Rx,y=rx,y⋅ejϕx,y.Equation (1) records the object light wave and reference light wave information of the artwork. Where ox,y represents the amplitude distribution of the object light wave, and φx,y represents the phase distribution of the object light wave. Similarly, rx,y represents the amplitude distribution of the reference light wave and ϕx,y represents the phase distribution of the reference light wave. Then the total light wave Tx,y of the digital holographic image of the artwork can be obtained by superposing the real functions of the amplitude and phase of the two light waves, and its distribution form is as follows:
(2)Tx,y=Ox,y+Rx,y.Equation (2) records the phase and amplitude information of the total light wave of the artwork, but this information can only record the phase distribution of the light wave of the artwork in the holographic projection, which is not conducive to image reproduction and processing, so it needs to be converted into the total light wave of the artwork intensity distribution information. The distribution form of the total light wave intensity Ix,y is as follows:
(3)Ix,y=Ox,y+Rx,y2=Ox,y2+Rx,y2+2ox,yrx,ycosφx,y−ϕx,y.Equation (3) records the total light wave intensity information of the artwork in the holographic projection, where Ox,y2 represents the intensity distribution of the object light wave of the artwork and Rx,y2 represents the intensity distribution of the reference light wave of the artwork. Fresnel diffraction holographic recording is to record the complex amplitude distribution of the object light wave and the reference light wave of the artwork on the basis of the wavefront recording to obtain the spatial frequency of the interference fringes in the holographic projection of the work to record the information of the holographic image of the work. The form of the complex amplitude distribution of the object light wave and the reference light wave is as follows:
(4)Ox′,y′=ox′,y′ejφx′,y′=ejdkλjd∬Ox0,y0ejkx′−x02+y′−y02/2ddx0dy0,Rx′,y′=rx′,y′ejϕx′,y′=e−jkx′sinα+y′sinβ.In equation (4), x0,y0 and x′,y′ represent the two-dimensional coordinates of the work of art on the object plane and the projection plane, respectively, and represent the distance between the two planes. According to the complex amplitude distribution of the object light wave and the reference light wave, the spatial frequency distribution of the interference fringes in the projection direction of the digital holographic projection image in Fresnel diffraction can be obtained as follows:
(5)fx=∂φ2π∂x′=x′−x0+dsinαλd,fy=∂ϕ2π∂y′=y′−y0+dsinβλd.Equation (5) records the spatial frequency of the interference fringes of the artwork according to the diffraction angle of Fresnel diffraction in the x and y directions and is similar to the lensless Fourier transform holographic recording method. The lensless Fourier transform does not use the reflection angle to record the spatial frequency but instead limits the bias conditions of the reference light wave to record the spatial frequency according to the Quist sampling principle. The conditions for the interference fringes to reach the highest spatial frequency in lensless Fourier transform holographic recording are as follows:
(6)fxmax=X+2x02λd≤12Δx,x0≥3X/2,fymax=Y+2y02λd≤12Δy,y0≥3Y/2.The image surface digital holographic recording method is mainly the process of imaging through the lens under the interference of the object light wave and the reference light wave through the principle of lens magnification. When studying image digital holographic recording, the influence of the lens’ numerical aperture on the imaging system is generally not considered. The frequency of the object light wave of the artwork recorded by the digital holographic image is as follows:(7)ηx=12π⋅∂φ∂x=fx02πm+xλmf,ηy=12π⋅∂ϕ∂x=fy02πm+yλmf.Equation (7) records the frequency of the object light wave in the x and y directions of the work of art, where the sum represents the spatial frequency of the initial object light wave emitted by the light source in the holographic projection shooting of the work of art, which is the magnification of the lens.


### 2.2. Digital Holographic Image Reconstruction Algorithm

According to the above research on digital holographic image recording methods, there are three holographic image reconstruction algorithms for digital holographic image reproduction of works of art: Fresnel diffraction integral, convolution algorithm, and angular spectrum algorithm [20, 21]. According to the approximate conditions of Fresnel diffraction, the form of the object light wave recorded in the hologram of the artwork can be obtained by the Fresnel diffraction integral formula as follows:
(8)Uxi,yi=eidk+ikxi2+yi2/λdλid⋅IIxi,yiRxi,yieπixi2+yi2/λd.In equation (8), Ix,y represents the light wave intensity of the hologram recorded by Fresnel diffraction and Rx,y represents the reproduction mode of the reference light wave recorded by the hologram. The Fourier transform method converts the recorded light wave information of the hologram into a discrete numerical recording form through photoelectric coupling. The object light wave reproduction form of the hologram of the artwork is as follows:
(9)Uxi,yi=eidk+πλid/MNxi2/Δx2+yi2/Δy2λid×DIIxi,yiRxi,yieπi/λdxi2Δx2+yi2Δy2.In equation (9), Δx and Δy are the pixel dimensions of the digital hologram recording tool, M and N represent the number of pixels of the recording tool, and DI represents the discrete Fourier transform operation. The convolution algorithm is based on the impulse response function of the digital holographic projection system and the discrete Fourier transform to obtain the object light wave distribution of the reproduced hologram. The form of the object light wave reproduced by the hologram is as follows:
(10)gxi,yi=diλi⋅ejkdi2+x−xi2+y−yi2di2+x−xi2+y−yi2,Uxi,yi=I−1IIxi,yi⋅Rxi,yi•Igxi,yi.In equation (10), I and I−1 represent the forward and inverse transform of the discrete Fourier transform and gxi,yi represents the impulse response function of the holographic projection system. The hologram reconstruction principle of the angular spectrum algorithm is to obtain the object light wave information reconstructed by the hologram through the transfer function of the holographic projection optical system and Fourier transform. The angular spectrum distribution of the holographic projection plane and the reproduction plane of the artwork is as follows:
(11)ux,y=∬Acosαλ,cosβλe2πicosα/λx+cosβ/λydfxdfy,hfx,fy=ejdk1−λfx2−λfy2,fx=cosαλ,fy=cosβλ.In equation (11), ux,y represents the light field distribution of the projection plane and the reproduction plane and hfx,fy represents the optical transfer function of the holographic projection system. According to the angular spectrum distribution, the light field intensity of the holographic projection reconstruction plane can be obtained as follows:
(12)Uxi,yi=I−1Iuxi,yi⋅hfx,fy.According to the principle of the above digital holographic image reconstruction algorithm, it can be seen that the three reconstruction algorithms all use the Fourier transform method. For the difference and comparison of the three algorithms, this article discusses their calculation formula, transformation space, and pixel size of the reconstructed image. The reproduction speed is compared and analyzed, and the comparison of the three algorithms is shown in Table1. It can be seen from the research results that the reconstruction speed of Fresnel diffraction is the fastest because Fourier image transformation is only carried out in the spatial domain, while convolution algorithm and angular spectrum reconstruction algorithm have more transformation process in the frequency domain, so the reconstruction speed is slower.Table 1
Comparison of digital hologram reconstruction algorithms.
Reproduction algorithmTransform spaceReproduction pixelReproduction speedFresnel diffractionSpace to frequencyΔxi=λd/NxΔx,Δyi=λd/NyΔyFastestConvolutionAirspace to frequency to airspaceΔxi=Δx,Δyi=ΔyMedium speedAngular spectrumAirspace to frequency to airspaceΔxi=Δx,Δyi=ΔySlowest


### 2.3. Digital Holographic Image Processing Technology

In the process of holographic projection display of digital artworks such as digital art galleries, galleries, and art exhibitions, in addition to the steps of recording and reproducing the images taken by the holographic projection of the works of art, it is also necessary to combine some image processing technologies to process the holographic projection images. A digital holographic image with a more realistic image and richer colors is obtained [22, 23]. According to the principle of transform space in the process of hologram recording and reproduction, the filter method is used to filter the spectrum of the hologram in the frequency domain and the space domain where the Fourier transform is performed [24]. The frequency spectrum of the virtual image reconstructed by the digital hologram is filtered out by setting the diaphragm, and then, the Fourier transform is performed to obtain a clear and realistic image of the real object. The spectrum of the hologram obtained after spectral filtering by filtering method is as follows:
(13)Ufx,fy=IOx,y2+IRx,y2+IOx,yR′x,y+IO′x,yRx,y.Filtering out the zero-order spectrum and conjugate virtual image in equation (13) and then performing Fourier transform, a relatively clear digital hologram can be obtained. Then, the light intensity method can be used to add and subtract the light intensity of the object light wave and the reference light wave of the obtained hologram. First, the light intensity distribution record of the original hologram is stored in the computer, and then, the intensity of the object light wave and the reference light wave are controlled until the light spot in the hologram is invisible or disappears, and then, the light intensity distribution of the hologram at this time is recorded [25]. Through the addition and subtraction of the light intensity, the digital hologram with the light spot removed can be obtained. In addition, the phase and amplitude distribution of the hologram can also be recorded and adjusted by the phase shift method. The phase shift method transforms the spatial phase of the reference light wave by shifting the phase of the projection plane and the reproduction plane of the holographic projection system to achieve interference with the light wave. The complex amplitude distribution of the object light wave on the projection plane obtained by the phase shift method is shown in equation (14), where Ix,y,θ represents the light intensity distribution of the hologram under different angular phase shifts.
(14)Ox,y=I1x,y,0−I3x,y,π+jI2x,y,π/2−I4x,y,3π/2λR′.


### 2.4. Digital Holographic Imaging and Reconstruction Simulation

In the process of holographic projection of artworks, it is necessary to go through the process of hologram imaging enlargement and reduction. It is one of the key technologies in holographic projection to ensure that there will be no blur and distortion in the process of hologram enlargement and imaging [26]. The magnification and imaging of the hologram are generally achieved by using a lens, so the diffracted light wave is usually a spherical wave, and the complex amplitude of the spherical wave of the reference light on the projection plane is as follows:
(15)Cx,y=Cde−jdk−jk/λdx−x02+y−y02.According to the principle of optical imaging, digital holographic magnification imaging mainly involves object light waves, reference light waves, recording light waves, and reproduced imaging light waves. Through the above study of object light waves and reference light waves, the horizontal magnificationMx and longitudinal magnification My of the digital hologram can be obtained. The calculation formula is as follows:
(16)Mx=±λdiλ0d0=1−d0di±λ0d0λdi−1,My=±λdi2λ0d02=λ0λMx2.λ0 and λ represent the wavelength of the recording light wave and the reproduced light wave, respectively, in the holographic projection imaging and d0 and di represent the object distance and the image distance, respectively, of the hologram of the artwork in the holographic projection. The horizontal and vertical magnification ratio of the image can be adjusted by adjusting the wavelengths of the recording light wave and the reproducing light wave, and combined with the abovementioned Fourier transform method, a desired magnification and distortion-free holographic image can be obtained.


## 2.1. Holographic Image Recording and Reproduction of Artworks

For object image recording methods, such as traditional camera shooting and projector projection, most of them are recorded according to the coordinates and pixel distribution of the physical object, and then, the object image is presented to the audience through the corresponding projection magnification equipment [16, 17]. The digital holographic projection uses the principle of virtual imaging to record the wavefront information of the light wave emitted by the object in the holographic projection device through the optical light wave phase and amplitude and then converts the recorded wavefront phase information into light wave intensity information and passes optical the principle of the process of reproduction. At present, the holographic image recording methods used in holographic projection technology mainly include three digital holographic image recording methods: Fresnel diffraction holographic recording, lensless Fourier transform holographic recording, and image surface digital holographic recording [18, 19]. Their main principle is to record based on the optical wavefront information reflected by the object, but the recording methods used are different. The process of wavefront recording is to convert the spatial phase information of the reflected light waves of the recorded object into spatial intensity information through light wave interference, which is also the core principle of optical holography technology. During the wavefront recording process, the information of the object light wave Ox,y and the reference light wave Rx,y will be recorded. They can be recorded in the following formats:
(1)Ox,y=ox,y⋅ejφx,y,Rx,y=rx,y⋅ejϕx,y.Equation (1) records the object light wave and reference light wave information of the artwork. Where ox,y represents the amplitude distribution of the object light wave, and φx,y represents the phase distribution of the object light wave. Similarly, rx,y represents the amplitude distribution of the reference light wave and ϕx,y represents the phase distribution of the reference light wave. Then the total light wave Tx,y of the digital holographic image of the artwork can be obtained by superposing the real functions of the amplitude and phase of the two light waves, and its distribution form is as follows:
(2)Tx,y=Ox,y+Rx,y.Equation (2) records the phase and amplitude information of the total light wave of the artwork, but this information can only record the phase distribution of the light wave of the artwork in the holographic projection, which is not conducive to image reproduction and processing, so it needs to be converted into the total light wave of the artwork intensity distribution information. The distribution form of the total light wave intensity Ix,y is as follows:
(3)Ix,y=Ox,y+Rx,y2=Ox,y2+Rx,y2+2ox,yrx,ycosφx,y−ϕx,y.Equation (3) records the total light wave intensity information of the artwork in the holographic projection, where Ox,y2 represents the intensity distribution of the object light wave of the artwork and Rx,y2 represents the intensity distribution of the reference light wave of the artwork. Fresnel diffraction holographic recording is to record the complex amplitude distribution of the object light wave and the reference light wave of the artwork on the basis of the wavefront recording to obtain the spatial frequency of the interference fringes in the holographic projection of the work to record the information of the holographic image of the work. The form of the complex amplitude distribution of the object light wave and the reference light wave is as follows:
(4)Ox′,y′=ox′,y′ejφx′,y′=ejdkλjd∬Ox0,y0ejkx′−x02+y′−y02/2ddx0dy0,Rx′,y′=rx′,y′ejϕx′,y′=e−jkx′sinα+y′sinβ.In equation (4), x0,y0 and x′,y′ represent the two-dimensional coordinates of the work of art on the object plane and the projection plane, respectively, and represent the distance between the two planes. According to the complex amplitude distribution of the object light wave and the reference light wave, the spatial frequency distribution of the interference fringes in the projection direction of the digital holographic projection image in Fresnel diffraction can be obtained as follows:
(5)fx=∂φ2π∂x′=x′−x0+dsinαλd,fy=∂ϕ2π∂y′=y′−y0+dsinβλd.Equation (5) records the spatial frequency of the interference fringes of the artwork according to the diffraction angle of Fresnel diffraction in the x and y directions and is similar to the lensless Fourier transform holographic recording method. The lensless Fourier transform does not use the reflection angle to record the spatial frequency but instead limits the bias conditions of the reference light wave to record the spatial frequency according to the Quist sampling principle. The conditions for the interference fringes to reach the highest spatial frequency in lensless Fourier transform holographic recording are as follows:
(6)fxmax=X+2x02λd≤12Δx,x0≥3X/2,fymax=Y+2y02λd≤12Δy,y0≥3Y/2.The image surface digital holographic recording method is mainly the process of imaging through the lens under the interference of the object light wave and the reference light wave through the principle of lens magnification. When studying image digital holographic recording, the influence of the lens’ numerical aperture on the imaging system is generally not considered. The frequency of the object light wave of the artwork recorded by the digital holographic image is as follows:(7)ηx=12π⋅∂φ∂x=fx02πm+xλmf,ηy=12π⋅∂ϕ∂x=fy02πm+yλmf.Equation (7) records the frequency of the object light wave in the x and y directions of the work of art, where the sum represents the spatial frequency of the initial object light wave emitted by the light source in the holographic projection shooting of the work of art, which is the magnification of the lens.


## 2.2. Digital Holographic Image Reconstruction Algorithm

According to the above research on digital holographic image recording methods, there are three holographic image reconstruction algorithms for digital holographic image reproduction of works of art: Fresnel diffraction integral, convolution algorithm, and angular spectrum algorithm [20, 21]. According to the approximate conditions of Fresnel diffraction, the form of the object light wave recorded in the hologram of the artwork can be obtained by the Fresnel diffraction integral formula as follows:
(8)Uxi,yi=eidk+ikxi2+yi2/λdλid⋅IIxi,yiRxi,yieπixi2+yi2/λd.In equation (8), Ix,y represents the light wave intensity of the hologram recorded by Fresnel diffraction and Rx,y represents the reproduction mode of the reference light wave recorded by the hologram. The Fourier transform method converts the recorded light wave information of the hologram into a discrete numerical recording form through photoelectric coupling. The object light wave reproduction form of the hologram of the artwork is as follows:
(9)Uxi,yi=eidk+πλid/MNxi2/Δx2+yi2/Δy2λid×DIIxi,yiRxi,yieπi/λdxi2Δx2+yi2Δy2.In equation (9), Δx and Δy are the pixel dimensions of the digital hologram recording tool, M and N represent the number of pixels of the recording tool, and DI represents the discrete Fourier transform operation. The convolution algorithm is based on the impulse response function of the digital holographic projection system and the discrete Fourier transform to obtain the object light wave distribution of the reproduced hologram. The form of the object light wave reproduced by the hologram is as follows:
(10)gxi,yi=diλi⋅ejkdi2+x−xi2+y−yi2di2+x−xi2+y−yi2,Uxi,yi=I−1IIxi,yi⋅Rxi,yi•Igxi,yi.In equation (10), I and I−1 represent the forward and inverse transform of the discrete Fourier transform and gxi,yi represents the impulse response function of the holographic projection system. The hologram reconstruction principle of the angular spectrum algorithm is to obtain the object light wave information reconstructed by the hologram through the transfer function of the holographic projection optical system and Fourier transform. The angular spectrum distribution of the holographic projection plane and the reproduction plane of the artwork is as follows:
(11)ux,y=∬Acosαλ,cosβλe2πicosα/λx+cosβ/λydfxdfy,hfx,fy=ejdk1−λfx2−λfy2,fx=cosαλ,fy=cosβλ.In equation (11), ux,y represents the light field distribution of the projection plane and the reproduction plane and hfx,fy represents the optical transfer function of the holographic projection system. According to the angular spectrum distribution, the light field intensity of the holographic projection reconstruction plane can be obtained as follows:
(12)Uxi,yi=I−1Iuxi,yi⋅hfx,fy.According to the principle of the above digital holographic image reconstruction algorithm, it can be seen that the three reconstruction algorithms all use the Fourier transform method. For the difference and comparison of the three algorithms, this article discusses their calculation formula, transformation space, and pixel size of the reconstructed image. The reproduction speed is compared and analyzed, and the comparison of the three algorithms is shown in Table1. It can be seen from the research results that the reconstruction speed of Fresnel diffraction is the fastest because Fourier image transformation is only carried out in the spatial domain, while convolution algorithm and angular spectrum reconstruction algorithm have more transformation process in the frequency domain, so the reconstruction speed is slower.Table 1
Comparison of digital hologram reconstruction algorithms.
Reproduction algorithmTransform spaceReproduction pixelReproduction speedFresnel diffractionSpace to frequencyΔxi=λd/NxΔx,Δyi=λd/NyΔyFastestConvolutionAirspace to frequency to airspaceΔxi=Δx,Δyi=ΔyMedium speedAngular spectrumAirspace to frequency to airspaceΔxi=Δx,Δyi=ΔySlowest


## 2.3. Digital Holographic Image Processing Technology

In the process of holographic projection display of digital artworks such as digital art galleries, galleries, and art exhibitions, in addition to the steps of recording and reproducing the images taken by the holographic projection of the works of art, it is also necessary to combine some image processing technologies to process the holographic projection images. A digital holographic image with a more realistic image and richer colors is obtained [22, 23]. According to the principle of transform space in the process of hologram recording and reproduction, the filter method is used to filter the spectrum of the hologram in the frequency domain and the space domain where the Fourier transform is performed [24]. The frequency spectrum of the virtual image reconstructed by the digital hologram is filtered out by setting the diaphragm, and then, the Fourier transform is performed to obtain a clear and realistic image of the real object. The spectrum of the hologram obtained after spectral filtering by filtering method is as follows:
(13)Ufx,fy=IOx,y2+IRx,y2+IOx,yR′x,y+IO′x,yRx,y.Filtering out the zero-order spectrum and conjugate virtual image in equation (13) and then performing Fourier transform, a relatively clear digital hologram can be obtained. Then, the light intensity method can be used to add and subtract the light intensity of the object light wave and the reference light wave of the obtained hologram. First, the light intensity distribution record of the original hologram is stored in the computer, and then, the intensity of the object light wave and the reference light wave are controlled until the light spot in the hologram is invisible or disappears, and then, the light intensity distribution of the hologram at this time is recorded [25]. Through the addition and subtraction of the light intensity, the digital hologram with the light spot removed can be obtained. In addition, the phase and amplitude distribution of the hologram can also be recorded and adjusted by the phase shift method. The phase shift method transforms the spatial phase of the reference light wave by shifting the phase of the projection plane and the reproduction plane of the holographic projection system to achieve interference with the light wave. The complex amplitude distribution of the object light wave on the projection plane obtained by the phase shift method is shown in equation (14), where Ix,y,θ represents the light intensity distribution of the hologram under different angular phase shifts.
(14)Ox,y=I1x,y,0−I3x,y,π+jI2x,y,π/2−I4x,y,3π/2λR′.


## 2.4. Digital Holographic Imaging and Reconstruction Simulation

In the process of holographic projection of artworks, it is necessary to go through the process of hologram imaging enlargement and reduction. It is one of the key technologies in holographic projection to ensure that there will be no blur and distortion in the process of hologram enlargement and imaging [26]. The magnification and imaging of the hologram are generally achieved by using a lens, so the diffracted light wave is usually a spherical wave, and the complex amplitude of the spherical wave of the reference light on the projection plane is as follows:
(15)Cx,y=Cde−jdk−jk/λdx−x02+y−y02.According to the principle of optical imaging, digital holographic magnification imaging mainly involves object light waves, reference light waves, recording light waves, and reproduced imaging light waves. Through the above study of object light waves and reference light waves, the horizontal magnificationMx and longitudinal magnification My of the digital hologram can be obtained. The calculation formula is as follows:
(16)Mx=±λdiλ0d0=1−d0di±λ0d0λdi−1,My=±λdi2λ0d02=λ0λMx2.λ0 and λ represent the wavelength of the recording light wave and the reproduced light wave, respectively, in the holographic projection imaging and d0 and di represent the object distance and the image distance, respectively, of the hologram of the artwork in the holographic projection. The horizontal and vertical magnification ratio of the image can be adjusted by adjusting the wavelengths of the recording light wave and the reproducing light wave, and combined with the abovementioned Fourier transform method, a desired magnification and distortion-free holographic image can be obtained.


## 3. Application Examples of the Holographic Projection Technology in the Digital Media Art

### 3.1. Research Object and Experimental Environment

The experimental objects of this research are artworks in art museums, galleries, and other art exhibitions that are exhibited to the public. In this paper, some artworks with complex structures and the consent of the creator are selected for holographic projection simulation experiments and the holographic projection technology is studied accordingly. This article first learns the knowledge of holographic projection and optical imaging and asks professionals for help and builds a simple holographic projection optical physical environment through purchase and lease. The main equipment includes adjustable light source, beam splitter, LCD lightwave recording board, CCD light wave reproduction board, and digital computer. According to the development of holographic technology, this paper proposes a digital holographic projection method combined with digital technology for complex physical image processing such as complex exposure, bleaching, denoising, and pixel difference removal in the early traditional optical holography and computed holographic imaging process. The holographic projection reproduction of artworks is transformed into a digital processing process. In order to study the application effect of holographic projection technology in the field of digital media art, this article sets up a control experiment to compare the quality and fidelity of the artwork obtained by various optical virtual imaging methods, and then, this article simulates the artwork obtained from the holographic projection experiment. The holographic images are uploaded to the media, and an online questionnaire on the “views and suggestions on the application of holographic projection technology to digital art museums and other digital media art fields” is randomly distributed. After experimental investigation and statistics, a total of 80 valid questionnaires were received.


### 3.2. Design of the Holographic Projection Simulation Experiment

According to the digital holographic recording and reproduction method of holographic projection technology in the second part, this article sets up multiple control experiments to discuss the advantages and disadvantages of digital holographic projection technology compared with other holographic technologies and image processing methods. The experimental group used analog digital holography technology to perform holographic image recording and reproduction steps on selected artwork samples, while the control group used traditional optical holography and computer holography technology for holographic image processing. This experiment is mainly divided into the following steps. First, build a holographic projection simulation test environment by collecting data and seeking help from holographic projection research professionals to understand the principles and main processes of holographic projection technology. Then, select artworks exhibited in art museums or galleries with the consent of the creator as the experimental objects and set up the experimental group and the control group to conduct holographic projection simulation experiments through different shooting and hologram recording and reproduction methods. In order to ensure the accuracy and reliability of the experiment, this article invites professional holographic projection film shooting workers who volunteer to participate in the experiment to provide guidance and suggestions. Through the light wave reflection and multiangle diffraction of the artwork by the adjustable light source, the phase and amplitude of the object light wave and the reference light wave of the artwork are recorded in the LCD light wave recording board and then uploaded to the digital computer for processing, and then, the artwork is reproduced by the CCD light wave reproduction board. Finally, upload the holographic projection image of the artwork obtained from the experiment to digital media and issue an online questionnaire to investigate the quality and experience effect of the holographic projection image of the experimental artwork and the audience’s application of the holographic projection technology to digital art museums and other digital media art fields. The basic principle of holographic projection imaging is shown in Figure1.Figure 1
Holographic projection imaging process of artwork.


### 3.3. Data Processing and Error Analysis

The survey data in this article is mainly divided into two parts, namely, the application of holographic projection technology for the holographic image recording and reproduction of artworks and the simulation experiment data and the opinions and suggestions on the application of holographic projection technology to digital art museums, galleries, and art exhibitions. The data processing and error analysis of this experiment are processed by SPSS20.0 software. For the statistical data of the experimental results, the analyses of variance and nonhomogeneity of variance are used to test the accuracy and error of the results. This method uses parameterα to represent all significant levels of experimental data between 0 and 1. The test level of this experimental data can reach α=0.05. In the data of the entire experimental group, excluding the influence of other factors, analyze the data under the change of a single factor and compare it with the average value and then perform error testing. For a set of experimental data, the number of data under a factor level that needs to be studied is denoted as n and the error is MSE; then, the analysis and test formula for the homogeneity of variance are shown in equation (17) as follows:
(17)L=MSE1ni+1nj.In the experiment, according to the different degrees of freedom of the variables, if the difference between the experimental group and the control group in groupk is to be tested, the variance and nonhomogeneity analysis method is generally used to test as shown in the following:
(18)S2=MSe1ni+1nj,D=X−k−X0−/S2.In the above formula,Xk− represents the data mean of the experimental group of group k, X0− represents the mean of the experimental data of its control group, and MSe represents the mean error variance. This test method can make the difference between the mean of multiple experimental groups and a control group. Multiple comparisons are used in this study to verify the conclusions drawn from the experimental results.


## 3.1. Research Object and Experimental Environment

The experimental objects of this research are artworks in art museums, galleries, and other art exhibitions that are exhibited to the public. In this paper, some artworks with complex structures and the consent of the creator are selected for holographic projection simulation experiments and the holographic projection technology is studied accordingly. This article first learns the knowledge of holographic projection and optical imaging and asks professionals for help and builds a simple holographic projection optical physical environment through purchase and lease. The main equipment includes adjustable light source, beam splitter, LCD lightwave recording board, CCD light wave reproduction board, and digital computer. According to the development of holographic technology, this paper proposes a digital holographic projection method combined with digital technology for complex physical image processing such as complex exposure, bleaching, denoising, and pixel difference removal in the early traditional optical holography and computed holographic imaging process. The holographic projection reproduction of artworks is transformed into a digital processing process. In order to study the application effect of holographic projection technology in the field of digital media art, this article sets up a control experiment to compare the quality and fidelity of the artwork obtained by various optical virtual imaging methods, and then, this article simulates the artwork obtained from the holographic projection experiment. The holographic images are uploaded to the media, and an online questionnaire on the “views and suggestions on the application of holographic projection technology to digital art museums and other digital media art fields” is randomly distributed. After experimental investigation and statistics, a total of 80 valid questionnaires were received.


## 3.2. Design of the Holographic Projection Simulation Experiment

According to the digital holographic recording and reproduction method of holographic projection technology in the second part, this article sets up multiple control experiments to discuss the advantages and disadvantages of digital holographic projection technology compared with other holographic technologies and image processing methods. The experimental group used analog digital holography technology to perform holographic image recording and reproduction steps on selected artwork samples, while the control group used traditional optical holography and computer holography technology for holographic image processing. This experiment is mainly divided into the following steps. First, build a holographic projection simulation test environment by collecting data and seeking help from holographic projection research professionals to understand the principles and main processes of holographic projection technology. Then, select artworks exhibited in art museums or galleries with the consent of the creator as the experimental objects and set up the experimental group and the control group to conduct holographic projection simulation experiments through different shooting and hologram recording and reproduction methods. In order to ensure the accuracy and reliability of the experiment, this article invites professional holographic projection film shooting workers who volunteer to participate in the experiment to provide guidance and suggestions. Through the light wave reflection and multiangle diffraction of the artwork by the adjustable light source, the phase and amplitude of the object light wave and the reference light wave of the artwork are recorded in the LCD light wave recording board and then uploaded to the digital computer for processing, and then, the artwork is reproduced by the CCD light wave reproduction board. Finally, upload the holographic projection image of the artwork obtained from the experiment to digital media and issue an online questionnaire to investigate the quality and experience effect of the holographic projection image of the experimental artwork and the audience’s application of the holographic projection technology to digital art museums and other digital media art fields. The basic principle of holographic projection imaging is shown in Figure1.Figure 1
Holographic projection imaging process of artwork.


## 3.3. Data Processing and Error Analysis

The survey data in this article is mainly divided into two parts, namely, the application of holographic projection technology for the holographic image recording and reproduction of artworks and the simulation experiment data and the opinions and suggestions on the application of holographic projection technology to digital art museums, galleries, and art exhibitions. The data processing and error analysis of this experiment are processed by SPSS20.0 software. For the statistical data of the experimental results, the analyses of variance and nonhomogeneity of variance are used to test the accuracy and error of the results. This method uses parameterα to represent all significant levels of experimental data between 0 and 1. The test level of this experimental data can reach α=0.05. In the data of the entire experimental group, excluding the influence of other factors, analyze the data under the change of a single factor and compare it with the average value and then perform error testing. For a set of experimental data, the number of data under a factor level that needs to be studied is denoted as n and the error is MSE; then, the analysis and test formula for the homogeneity of variance are shown in equation (17) as follows:
(17)L=MSE1ni+1nj.In the experiment, according to the different degrees of freedom of the variables, if the difference between the experimental group and the control group in groupk is to be tested, the variance and nonhomogeneity analysis method is generally used to test as shown in the following:
(18)S2=MSe1ni+1nj,D=X−k−X0−/S2.In the above formula,Xk− represents the data mean of the experimental group of group k, X0− represents the mean of the experimental data of its control group, and MSe represents the mean error variance. This test method can make the difference between the mean of multiple experimental groups and a control group. Multiple comparisons are used in this study to verify the conclusions drawn from the experimental results.


## 4. Discussion on the Application of the Holographic Projection Technology in the Digital Media Art

### 4.1. Development History of the Holographic Projection Technology

According to related literature research, this article investigates the four stages of development of holographic projection technology. This article divides holographic projection technology into four development stages: budding, development, maturity, and prosperity. As shown in Table2, this article briefly introduces the recording media, reproduction methods, and representative applications of the various stages of holographic projection. In the development process from budding to prosperity, holographic projection technology has mainly experienced mercury lamp light source recording, white light recording, laser recording, and digital light source recording. The corresponding reproduction methods also range from light source reproduction to laser reproduction and finally to digital reproduction. The principle is to record and reproduce based on optical holography. The difference is that with the development of digital media, holographic projection gradually combines computer image processing and other digital technologies to make holographic projection images clearer and richer in colors. The representative applications of holographic projection in these periods are in-line holograms, off-axis holograms, rainbow holograms, and digital holograms.Table 2
Development period of holographic projection technology.
PhaseDevelopment periodRecording mediumReproduction methodRepresentativeFirstBudMercury lampLight reproductionCoaxial holographySecondDevelopmentWhite lightLight reproductionOff-axis holographyThirdMatureLaserLaser reproductionRainbow hologramFourthPeakDigital light sourceDigital reproductionDigital holographyThe application of holographic projection technology and 3D technology is most closely related. In order to study the application of holographic projection technology, this article investigates and understands the 3D technology related to holographic projection. The survey results are shown in Figure2. At present, the main holographic technologies are divided into optical holography, computational holography, and digital holography. These holographic technologies are mainly put into practical application by combining five 3D technologies including air projection and interaction, laser projection of solid 3D images, 360 holographic display screen, and edge blanking technology.Figure 2
Holographic technology and related 3D technology applications.


### 4.2. Analysis of Simulation Experiment of Holographic Projection

Through the in-depth study of holographic projection technology, this article conducts a simulated holographic projection experiment on artworks. The holographic projection image obtained in the experiment is shown in Table3. This article mainly analyzes the image reproduction effect of holographic projection from the image quality and the similarity of the actual comparison with the artwork.Table 3
Comparison results of holographic projection simulation experiment.
ItemClassNumberMeanSDTPImage qualityExperimental2012.6671.7960.2560.216Control2011.8251.5742.2350.007Image similarityExperimental2015.4681.918-0.2230.825Control2012.1762.2670.3120.754According to the experimental data in Table3, the error accuracy and inspection level of the experimental data shown in Figure 3 are obtained by processing statistics. It can be seen from the figure that the maximum standard deviation of the error mean of the experimental data in this paper is 2.267, and it is obvious that this is a set of abnormal data by comparing with other sets of data. Therefore, the highest accuracy of the data in this paper should be 1.918, which belongs to higher accuracy.Figure 3
Error accuracy and test level of experimental data.According to the experimental data, this article records the phase, amplitude, diffraction angle, light wave intensity, and simulation effect changes of several experimental groups and control groups during the holographic projection simulation experiment of artworks. As shown in Table4, the best simulation effect can be achieved when the light intensity is 50.64 and the simulation accuracy of the hologram at this time reaches 93.34%.Table 4
Light wave phase and amplitude and simulation accuracy changes in the simulation experiment.
Sample numberPhaseAmplitudeDiffraction angleLight intensitySimulation effectE101.876043.7691.06%C10.25∗π2.5646054.3579.86%E20.5∗π3.95112044.6983.25%C2π5.46718038.7676.89%E31.5∗π7.98424049.8687.65%C32∗π9.89736050.6493.34%According to the Fresnel diffraction recording research of holographic projection technology, this paper records the simulation accuracy of holographic images of artworks recorded under different diffraction angles. As shown in Figure4, under the diffraction angle of −80 degrees to 80 degrees, the error accuracy of the quality and similarity of the holographic image has been controlled below the level of 0.6.Figure 4
The accuracy of holographic projection images under different diffraction angles.


### 4.3. Validation of Holographic Projection Image Effect of the Artwork

According to the image quality evaluation standard, this article evaluates the quality of the holographic image of the artwork obtained from the experiment, mainly from the signal-to-noise ratio of the hologram PSNR, structural similarity SSIM, mean square error MSE, normalized mean square distanced. The average absolute distance r is analyzed. In addition, this article also compares the quality of the images obtained by several holographic techniques and ordinary photography techniques that do not use holography. The results are shown in Table 5.Table 5
Image quality of artworks by different shooting techniques.
TypeTechnologyPSNRSSIMMSEdrOrdinary shootingCamera shot25.320.82370.35260.18730.14363D shooting27.430.89460.32730.20360.1563Holographic projectionOptical holography28.140.89730.24610.14720.0958Computational holography28.960.90250.40250.23650.1847Digital holography29.670.91640.23640.14370.0975According to the experimental test results in Table5, this paper draws a line chart of the comparative analysis of image quality of several artwork image shooting techniques, as shown in Figure 5. This experiment mainly researches and discusses the image capturing technology including the nonholographic technology, optical holography, computerized holography, and digital holography technology in 3D photography and holographic technology. It can be seen from the figure that the holographic image obtained by digital holographic projection has the lowest mean square error, normalized mean square distance, or normalized average absolute distance.Figure 5
Image quality of artworks by different shooting techniques.


### 4.4. Audience’s Attitude towards Application of Holographic Projection to the Exhibition of Digital Artworks

This article analyzes the audience’s awareness and acceptance of holographic projection from the results of online questionnaires and experimental data, mainly from the audience’s evaluation of the image quality and experience effects of holographic projection of artworks and the application of holographic projection technology to the digital art. The attitude of the museum is discussed and analyzed. As shown in Table6, according to the audience’s attitude, it is divided into five levels: A, B, C, D, and E to reflect the audience’s attitude of strongly welcoming, supporting, indifferent, undesirable, and strongly opposed to the application of holographic projection technology in the field of the digital media art.Table 6
The audience’s evaluation and attitude towards the effect of holographic projection.
InvestorsNumberProportionTotalEvaluationSortA4556.25%59.86%8.982B5163.75%61.59%7.591C3746.25%50.24%6.164D3948.75%46.37%5.943E2126.25%34.76%4.735The audience’s perception of the holographic projection technology and its application in digital media art fields such as digital art galleries, digital galleries, digital art exhibitions, and other art exhibitions are shown in Figure6. It can be seen from the figure that most audiences have a high evaluation of the multisensory virtual experience of holographic projection and up to 59.86% of the audience strongly support the application of holographic projection in the field of the digital media art.Figure 6
Audience’s perception and attitude towards holographic projection technology.


## 4.1. Development History of the Holographic Projection Technology

According to related literature research, this article investigates the four stages of development of holographic projection technology. This article divides holographic projection technology into four development stages: budding, development, maturity, and prosperity. As shown in Table2, this article briefly introduces the recording media, reproduction methods, and representative applications of the various stages of holographic projection. In the development process from budding to prosperity, holographic projection technology has mainly experienced mercury lamp light source recording, white light recording, laser recording, and digital light source recording. The corresponding reproduction methods also range from light source reproduction to laser reproduction and finally to digital reproduction. The principle is to record and reproduce based on optical holography. The difference is that with the development of digital media, holographic projection gradually combines computer image processing and other digital technologies to make holographic projection images clearer and richer in colors. The representative applications of holographic projection in these periods are in-line holograms, off-axis holograms, rainbow holograms, and digital holograms.Table 2
Development period of holographic projection technology.
PhaseDevelopment periodRecording mediumReproduction methodRepresentativeFirstBudMercury lampLight reproductionCoaxial holographySecondDevelopmentWhite lightLight reproductionOff-axis holographyThirdMatureLaserLaser reproductionRainbow hologramFourthPeakDigital light sourceDigital reproductionDigital holographyThe application of holographic projection technology and 3D technology is most closely related. In order to study the application of holographic projection technology, this article investigates and understands the 3D technology related to holographic projection. The survey results are shown in Figure2. At present, the main holographic technologies are divided into optical holography, computational holography, and digital holography. These holographic technologies are mainly put into practical application by combining five 3D technologies including air projection and interaction, laser projection of solid 3D images, 360 holographic display screen, and edge blanking technology.Figure 2
Holographic technology and related 3D technology applications.


## 4.2. Analysis of Simulation Experiment of Holographic Projection

Through the in-depth study of holographic projection technology, this article conducts a simulated holographic projection experiment on artworks. The holographic projection image obtained in the experiment is shown in Table3. This article mainly analyzes the image reproduction effect of holographic projection from the image quality and the similarity of the actual comparison with the artwork.Table 3
Comparison results of holographic projection simulation experiment.
ItemClassNumberMeanSDTPImage qualityExperimental2012.6671.7960.2560.216Control2011.8251.5742.2350.007Image similarityExperimental2015.4681.918-0.2230.825Control2012.1762.2670.3120.754According to the experimental data in Table3, the error accuracy and inspection level of the experimental data shown in Figure 3 are obtained by processing statistics. It can be seen from the figure that the maximum standard deviation of the error mean of the experimental data in this paper is 2.267, and it is obvious that this is a set of abnormal data by comparing with other sets of data. Therefore, the highest accuracy of the data in this paper should be 1.918, which belongs to higher accuracy.Figure 3
Error accuracy and test level of experimental data.According to the experimental data, this article records the phase, amplitude, diffraction angle, light wave intensity, and simulation effect changes of several experimental groups and control groups during the holographic projection simulation experiment of artworks. As shown in Table4, the best simulation effect can be achieved when the light intensity is 50.64 and the simulation accuracy of the hologram at this time reaches 93.34%.Table 4
Light wave phase and amplitude and simulation accuracy changes in the simulation experiment.
Sample numberPhaseAmplitudeDiffraction angleLight intensitySimulation effectE101.876043.7691.06%C10.25∗π2.5646054.3579.86%E20.5∗π3.95112044.6983.25%C2π5.46718038.7676.89%E31.5∗π7.98424049.8687.65%C32∗π9.89736050.6493.34%According to the Fresnel diffraction recording research of holographic projection technology, this paper records the simulation accuracy of holographic images of artworks recorded under different diffraction angles. As shown in Figure4, under the diffraction angle of −80 degrees to 80 degrees, the error accuracy of the quality and similarity of the holographic image has been controlled below the level of 0.6.Figure 4
The accuracy of holographic projection images under different diffraction angles.


## 4.3. Validation of Holographic Projection Image Effect of the Artwork

According to the image quality evaluation standard, this article evaluates the quality of the holographic image of the artwork obtained from the experiment, mainly from the signal-to-noise ratio of the hologram PSNR, structural similarity SSIM, mean square error MSE, normalized mean square distanced. The average absolute distance r is analyzed. In addition, this article also compares the quality of the images obtained by several holographic techniques and ordinary photography techniques that do not use holography. The results are shown in Table 5.Table 5
Image quality of artworks by different shooting techniques.
TypeTechnologyPSNRSSIMMSEdrOrdinary shootingCamera shot25.320.82370.35260.18730.14363D shooting27.430.89460.32730.20360.1563Holographic projectionOptical holography28.140.89730.24610.14720.0958Computational holography28.960.90250.40250.23650.1847Digital holography29.670.91640.23640.14370.0975According to the experimental test results in Table5, this paper draws a line chart of the comparative analysis of image quality of several artwork image shooting techniques, as shown in Figure 5. This experiment mainly researches and discusses the image capturing technology including the nonholographic technology, optical holography, computerized holography, and digital holography technology in 3D photography and holographic technology. It can be seen from the figure that the holographic image obtained by digital holographic projection has the lowest mean square error, normalized mean square distance, or normalized average absolute distance.Figure 5
Image quality of artworks by different shooting techniques.


## 4.4. Audience’s Attitude towards Application of Holographic Projection to the Exhibition of Digital Artworks

This article analyzes the audience’s awareness and acceptance of holographic projection from the results of online questionnaires and experimental data, mainly from the audience’s evaluation of the image quality and experience effects of holographic projection of artworks and the application of holographic projection technology to the digital art. The attitude of the museum is discussed and analyzed. As shown in Table6, according to the audience’s attitude, it is divided into five levels: A, B, C, D, and E to reflect the audience’s attitude of strongly welcoming, supporting, indifferent, undesirable, and strongly opposed to the application of holographic projection technology in the field of the digital media art.Table 6
The audience’s evaluation and attitude towards the effect of holographic projection.
InvestorsNumberProportionTotalEvaluationSortA4556.25%59.86%8.982B5163.75%61.59%7.591C3746.25%50.24%6.164D3948.75%46.37%5.943E2126.25%34.76%4.735The audience’s perception of the holographic projection technology and its application in digital media art fields such as digital art galleries, digital galleries, digital art exhibitions, and other art exhibitions are shown in Figure6. It can be seen from the figure that most audiences have a high evaluation of the multisensory virtual experience of holographic projection and up to 59.86% of the audience strongly support the application of holographic projection in the field of the digital media art.Figure 6
Audience’s perception and attitude towards holographic projection technology.


## 5. Conclusions

Since its introduction, holographic technology has been welcomed by various industries and paid attention to from all walks of life and has broad development prospects. Some of these holographic technologies still remain in theoretical research and have not been truly realized. Among the holographic technologies that have been realized, digital holographic projection is undoubtedly the best. Holographic projection technology has important applications in various fields. For example, 3D animation production, VR virtual technology, and 3D virtual game development all use the method of virtual imaging in holographic projection to bring people a multisensory three-dimensional virtual experience. This paper discusses the current application status of holographic projection technology in the field of digital media art and finds that the main application of holographic projection technology is in the production of film and game in digital media art. Based on this, this article proposes to apply holographic projection technology to the construction of digital art museums and digital media art exhibitions.This paper sets up the holographic projection simulation experiment of the artwork, using the Fresnel diffraction method and Fourier transform to record the phase and amplitude information of the diffracted light wave of the holographic projection image of the artwork under the adjustable light source, and through the Fresnel integration Algorithm, inverse Fourier transform, convolution reconstruction algorithm, and angular spectrum reconstruction algorithm are the processes of projection and reconstruction of the recorded hologram. In this paper, a computer digital holographic projection system is used to drive the process of recording and reproducing the holographic image of the artwork and the computer image processing technology is used to collect the experimental simulation holographic projection image and output the processed image after digital image transformation, so as to realize the holographic recording and reproduction of the artwork. The study found that after the holographic projection and computer image processing, the holographic image of the artwork obtained can still maintain the original quality and the degree of simulation is high, indicating that it is feasible to apply the holographic projection technology to digital art fields such as digital art galleries, this will be of great significance to the development of digital media art.Since the holographic projection technology is a novel digital holographic technology and researchers in some fields have not yet realized and put it into application at the theoretical stage and the understanding of the holographic projection technology in this article is not deep enough, there are still some shortcomings in this article. For example, the construction of the optical physical environment for holographic projection is limited by economic conditions and knowledge reserves, so it is relatively crude, which causes large errors in the experimental results, and the immature operation of the holographic projection process may also cause the accuracy of the experimental results to decrease. I hope that in the future, we can improve and continue to in-depth study the holographic projection technology in the field of digital media art more in-depth and broader applications. The research in this article is the author’s own discussion on the application of the holographic projection technology in the field of digital media art, and there is no plagiarism and interest competition. The manuscripts of all the contents of this article have been reviewed by relevant personnel and have not been published or submitted for publication elsewhere and agree to submit them to your journal.



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*Source: 9997037-2021-05-19.xml*