Authenticity in the Design of Digital Heritage Applications

In philosophy and psychology, individuals have historically been examined in light of their interactions with others and with the physical environment. This concept has been explored across various disciplines, its roots extending back to ancient Greek philosophers. Derived from the Greek word authentikós (autós: self), it has been a subject of philosophical discourse, notably within Western philosophy, where there has been a longstanding focus on the individual. This focus often delineates between a “private” and a “public” self, shaping its relationship with society. Questions such as “Who am I?” and “What is my authentic self?” Is at the bottom of the concept of self-judgment [2]. Prior to Hegel, sincerity, honesty, and moral values were considered more relevant than authenticity, linked to the potential of knowing oneself and acting accordingly, honest and truthful by society. However, the concept of authenticity also encompasses being true to oneself for personal fulfilment, independent from societal expectations, in a continuous search for a balance between identity and authenticity. This highlights the significance of recent psychological and social science research on introverted and extroverted traits [4]. Extroverts have been found to more readily perceive authenticity, while, on the other hand, studies have also shown that introverts, when prompted to act as if they were extroverted, were equally capable of perceiving authentic experiences [5]. Building on this idea, [6] Wilt et al. have defined a “Subjective Authenticity” that emerges when one behaves in accordance with their genuine self-concept. This definition highlights the importance, also in UX design, to let individuals express themselves, discover personal meaning, and engage in reflection; only through this self-expression or self-reflection it is possible to nurture a perception of authenticity. Moreover, there are other components that have been recently studied as being relevant. It is the case of “concentration” and “sense of direction”. Grandey et al. [7], for instance, has studied how authenticity emerges only when distractions are limited, while Pescarin and Martinez Pandiani [8] have highlighted that this process impacts also knowledge acquisition and engagement in serious games. Also, disorientation may produce a negative effect on the perception of authenticity such as any situation that can create a discomfort in the participants of an experience [9] [10]. There are other aspects, connected to the personal disposition or to the context a person live in, that are also relevant and may modify significantly the sense of authenticity, including: personal expectations, emerging emotions and sensations, the previous knowledge one own and the desire to acquire new knowledge and to remember it (the “memorability” quoted by [11]), the possibility to act and to make a choice [12] and also the challenges one may experience, since they can be interpreted as opportunities to grow [13]. All these aspects relate to authenticity and to its “Self” dimension. Although many studies have been conducted to explore them, we prefer here to quote Karl Jasper, a psychologist and philosopher who probably better than others was able to summarise the complexity of this dimension already in 1919. In his “Psychology of WorldViews” [14], he wrote that authenticity emerges when it resonates with an individual’s deepest self, enduring, evolving, and evolving alongside the person. Jasper therefore, beyond the concepts described in the first part of this chapter, had already introduced the notions of depth (the opposite of superificiality), time, and evolution. Following Jasper, an authentic experience is therefore something perceived as deeply personal and meaningful, unique to everyone, subject to change over time, and capable of being nurtured through introspective engagement.

Although pivotal to any experience, the Self is continuously in relation to other people (its social or “Others” dimension). Therefore, one important aspects to consider is the interconnecting components between the Self and the Others, by mean of formal or informal communication, expressed and explicit (low-context) or internal and implicit (high-context), spoken with natural language or with symbolic gestures. Authenticity, in fact, has been defined as a social psychological phenomenon, structured around social practices [15] such as activities shared with others (challenges, competition, cooperation), ruled by social norms. This phenomenon is based on action. According to Coupland [16], authenticity has a performative aspect (“authentication”), intended as an active process that involves action, verbal exposition and dialogue. Dialogue is therefore a crucial component in authenticity, not only when other people are around, but also when they are not (inner dialogue) or when they are potentially there (potential dialogue), such as when there is the desire to exchange experiences and thoughts, after an experience. The value of verbal exchange emerges also in what has been defined as the “mediated dialogue” approach by McKenney et al. [17], that can be facilitated by community building, development of personal connections, exploration of alternative perspectives and by a summarising and reflective moment at the end of the experience (https://www.sitesofconscience.org/). This approach was adopted also to design interactive VR experiences, as in the case of the Emotive EU project [18], where social gestures have been developed to strengthen embodiment and social dimension, reinforced by solicited dialogue among users, triggered by provocative questions and “emotive” tone of voice.

The last pillar of authenticity, is the external world, intended here both as the physical world, where the experience takes place, but also as the digital environment with digital objects, either reproduction of physical ones or as reconstruction or completely digitally born virtual elements. The “World” dimension is particularly relevant in this book, where the materiality of the artworks is at the bottom of any digital representation. The component of “truthfulness”, that requires a process of verification [2], is often used also in tourism studies, where users often report to search for something “faithful to an original” or “of unquestioned origin or authorship”. Authenticity is among the most important expectations for tourists [11] and it is often mentioned in relation with realism, accuracy and objectivity [19], with realism being strictly connected to a physical context, its characteristics and properties. However, according to Vico [20], this faithful representation may not be authentic or a true reproduction of the artwork: a digital object represents the original not only in terms of appearance, but also in terms of context, meaning and use. Meticulous documentation of the digitisation and interpretation process are therefore crucial to maintaining a sense of authenticity in digital replicas through validation and interpretation processes. In Computer Science and specifically in the development of VR and XR experiences, authenticity is frequently associated with the sense of presence, interaction and immersivity that produce an “embodiment” in a digital space, but also with the graphical realism of the virtual environments [21]. Beyond the realism, there are other two aspects that emerge as crucial in serious games studies for the perception of authenticity: randomness and unexpected elements [22]. There is a last aspect that is emerging in recent studies of design and architecture, that is the concept of “atmosphere”, a dynamic subjective phenomenon, perceptual, sensory, and emotive [23]. Although it is a subjective element and it should be included in the “Self” dimensions, this concept has a direct relation with the “World”, and to the effort designers and developers put in the creation of a “mood” to be applied either to a single digital scenario or to an entire UX. It can be therefore interpreted as a quality of a place that can “move” people, making them feel emotions or triggering sensations or also memories. In tourism studies, Zimmermann [24] stated that developing an atmosphere of the past can satisfy users’ needs of authenticity, while it also can produce “place attachment” in cultural tourism [25].

In this section we describe an experimental survey carried out to further extend, explore and test the initial findings obtained with the analysis of previous works. With this experiment we aimed at identifying and understanding how perceptions of authenticity vary across different contexts, focusing specifically on the cultural one. We have therefore adopted a specific qualitative method that required the design and development of Cultural Probe Kits (CPK). Described by Gaver et al. [26], CPKs are tools for self-reporting (i.e. diaries or activity workbooks), that allow participants to observe, think about, and describe their experiences, in situations where it is not possible to undertake direct observations, or when it is to avoid interference of researchers or in situation where there are privacy issues and time limits. They are distributed to participants, facilitating the documentation of particular sensations, emotions, or experiences [27].

In 2022, we have specifically designed a CPK for this purpose [3]. Although acquired inputs have been only qualitative, this exploration proved to be extremely useful in the integration and refinement of the concept of authenticity, detailing components and elements. During that experiment we have involved a uniform group of participants, consisting of potential users of virtual museums [28].

In the CPK we included a diary and an activity workbook. The activities were meant to explore multiple aspects around the following research questions:

Our objectives included the following: exploring the relationship between perceived authenticity and emotions; identifying the primary emotion associated with authentic experiences (among Fear, Happiness, Sadness, Disgust, Anger, and Surprise); determining the predominant senses and corresponding stimuli involved (among sight/visuals, hearing/sounds, touch, smell, and taste); investigating the correlation between authenticity, trustworthiness, and reliability; gaining insights into individuals’ perceptions of genuine digital experiences; examining the relationship between the realism of digital scenarios and the perception of authenticity; and comparing the stimuli and triggers encountered in everyday life with those experienced in digital contexts.

In line with our initial research question, we structured our methodology to include a series of tasks for participants during their museum visit. These tasks involved capturing two distinct photos: one representing authenticity and the other depicting inauthenticity, accompanied by explanatory comments. Additionally, participants completed a writing task in which they reported a personal story describing a significant, authentic life event, supported by a relevant photograph. This narrative approach aimed to delve deeper into participants’ thoughts and emotions surrounding their perception of authenticity. To address the third question, participants were encouraged to keep a diary for eight days, documenting their experiences to track the frequency of specific events over time. Finally, we administered a series of online questions tailored to explore the final research question. The findings revealed several key insights:

The Self encounters, identifies with, and collides with the Other (who is also a Self) within a temporal and spatial environment (the World), through a system of interactions to achieve an authentic experience [3]. Authenticity, therefore, begins with the Self; it touches the innermost self and endures, develops, and evolves with it. We have confirmed that authenticity is characterised by three interconnected dimensions, with most components being unique to one of them (i.e., others–dialogue, world–atmosphere). These three dimensions are: the Self, the Other, and the World.

From our investigations, it has become evident that grasping the essence of authenticity within hybrid and XR cultural experiences demands a thorough and multidimensional examination. This segment is dedicated to delving into the intricate nature of authenticity, elucidating its emergence through the convergence of theoretical frameworks and practical observations. Through this method, our aim is to delineate a conceptual model capable of effectively guiding both the crafting and evaluation of genuine experiences. The complexity inherent in authenticity reveals itself through myriad facets, reflecting the richness and diversity of its dimensions and constituents. These discernible traits transcend mere summation, weaving together in distinct configurations that yield deeply personal and profound encounters. Our inquiry commences with the premise that authenticity defies static definitions or narrow criteria; rather, it manifests through a mosaic of qualitative and quantitative elements, interacting in intricate and often unpredictable ways. Within this context, literature and empirical findings assume pivotal roles in unveiling authenticity’s multifaceted nature. While literature furnishes us with theoretical underpinnings and fundamental concepts, empirical insights gleaned from fieldwork and qualitative analyses enrich this foundation with firsthand, contextual revelations. The synergy between these approaches offers fresh perspectives, suggesting that each authentic encounter arises from a unique amalgamation of interconnected components, inherently imbued with personal and subjective perspectives. Nonetheless, cognizant of this complexity, our aim was to distil a broad and concise definition of an “authentic experience,” with the specific intent of aiding the design of interactive experiences. Addressing this complexity necessitates a comprehensive approach that acknowledges and integrates the myriad facets and interrelations of authenticity’s constituents. This entails meticulous consideration of how these elements coalesce to engender experiences that resonate with authenticity. It is within this intricate tapestry of elements that the true essence of authenticity resides, rendering each experience distinctive and irreplicable.

In the following section we detail dimensions, components and elements.

How designers can develop ideas in line with the authenticity framework? To answer to this question, we have developed a tool that starts from the elements and actionable design hints described above and supports two stages of design: “identification of audience’s goals” and “idea generation”.

Within the European project GIFT (https://gifting.digital/), a deck of cards known as “Visitor Toolbox” has been redesigned and made available for museum professionals and designers working for cultural institutions [33]. This tool organised and supported co-creation activities following the five stages of design: 1. Context definition, 2. Institutional goals, 3. Design brief, 4. Ideation and storyboarding, 5. Disruption.

Unfortunately, although extremely useful, it doesn’t enable to design taking into consideration cognitive and emotional goals that the designers and institutions could take as reference in their project. Therefore, within PERCEIVE project we have first of all created an extension for the Visitor Toolbox, adding specific cards to a new stage (Audience goals) and to the ideation phase. After a testing phase, we have then decided to develop a new deck of cards, initially as a paper boardgame design experience, and finally as a collaborative webapp, also enabling hybrid co-design sessions. This tool will be described in Volume 2. We include here the description of the different included elements for the design stages.

In the reproduction of artworks, authenticity is applied by staying true to the historical context and the original artist’s intentions. When recreating historical artifacts or artworks, the aim is not to produce exact replicas but to authentically represent the original artwork’s essence and reveal the process of reproduction. This allows viewers to observe both the current state of the artwork and its condition at the time of its creation. Three exemplary cases that illustrate the importance of authenticity in restoration are the practice of Kintsugi [Fig. 4], The Fate of the Animals by Franz Marc [Fig. 5], and Marcel Duchamp’s The Large Glass [Fig. 6].

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Kintsugi, or “golden joinery,” is the Japanese art of repairing broken pottery using lacquer mixed with powdered gold, silver, or platinum. Rather than concealing the cracks, this technique highlights them, celebrating the object’s imperfections as part of its history. As a philosophy, kintsugi reflects the Japanese aesthetic of wabi-sabi, embracing imperfection and transience. It emphasizes the beauty of wear and tear, viewing cracks and repairs as integral parts of an object’s life rather than flaws to be hidden. Overall, kintsugi embodies a profound philosophy that finds beauty and meaning in imperfection, offering a unique perspective on the nature of existence and the passage of time¹. One of the most famous examples of Kintsugi practice is the Golden Tea Bowl, also known as the “Kintsugi Chawan.“ This tea bowl dating back to the 15th century, is housed in the Tokyo National Museum in Japan [Fig. 4]. It gained widespread recognition for its exquisite repair work, which includes intricate golden seams running along its cracks. The Golden Tea Bowl exemplifies the artistry and philosophy of Kintsugi, showcasing how imperfections can be transformed into sources of beauty and admiration. The process of mending pottery through Kintsugi can be seen as a form of restoration, but with a distinctive philosophical twist. In traditional restoration, the goal is often to restore an object to its original state, minimizing or concealing any evidence of damage. However, Kintsugi embraces the object’s history, including its imperfections, by highlighting the cracks with gold or other precious materials. This approach reflects a restoration that not only preserves the functional and aesthetic value of the pottery but also transforms it into something new, celebrating its “flaws” as part of its narrative. Therefore, in a broader sense, Kintsugi could be viewed as a form of “authentic” restoration, as it retains a connection between the original and restored elements, preserving the integrity of the object by respecting its history and the passage of time.

The artwork “Fate of the Animals” is a renowned painting by Franz Marc, created in 1913 during the Der Blaue Reiter movement [Fig. 5]. The artwork, oil on canvas, depicts a chaotic scene of animals amidst destruction, contrasting Marc’s usual peaceful animal portrayals. Following damage to the painting’s in a 1916 warehouse fire, Paul Klee, a close friend of Marc, undertook its restoration². Klee utilized old photographs and added a brownish tint to the paint, creating a notable variation. Although speculative, some scholars propose that Klee’s use of the brown tint was intended to distinguish between the original and restored sections of the painting. Whatever the reasons Paul Klee’s restoration techniques on “Fate of the Animals” were, the viewer can discern the distinction between Franz Marc’s original work and Klee’s restoration efforts. This discernment not only preserves a high degree of authenticity but also enriches the painting’s narrative. By referencing the restoration process in the painting’s aesthetics, the viewer gains insight into the history and evolution of the artwork, further enhancing its significance.

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In the realm of art, authenticity holds profound significance, shaping our perception and appreciation of objects. In The Fate of the Animals by Franz Marc, authenticity is preserved through Paul Klee’s act of repainting the damaged areas, while simultaneously lowering the tones of the painting to match how they would have appeared originally. Similarly, the art of Kintsugi embodies authenticity in a different form, emphasizing the beauty of imperfection and the inherent value of repair. Instead of discarding or attempting to hide the damage, Kintsugi artisans embrace the cracks and fractures as integral parts of the object’s story while restoring its functionality. In both the Fate of the Animals and Kintsugi, authenticity emerges from a deep appreciation of the object’s journey, as each imperfection, whether it’s a brushstroke on a painting or a crack in a ceramic vessel, becomes a testament to the object’s history and the hands that have shaped it. In essence, the Fate of the Animals and Kintsugi offer profound insights into the nature of restoration in art, in that the goal of a restoration must always involve authenticity, which in the case of the above examples can be understood as keeping the artwork’s original essence or features during restoration processes. Such approaches ensure that any restoration allows a clear connection between the original elements and the restored aspects, so that viewers can discern the difference between what was original and what was restored. The emphasis is on maintaining the cultural and historical value of the artwork while allowing it to be appreciated in its restored form.

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In the article by Bryony Bery on the reconstruction of Marcel Duchamp’s “The Bride Stripped Bare by Her Bachelors, Even” by Richard Hamilton³, the author traces the journey of the artwork known today as the Large Glass, from its creation to its multiple exhibitions, breakages, repairs, and reconstructions, shedding light on the challenges posed by its physical state and, more importantly, on debates surrounding authenticity of replications and restorations in art history. The timeline of Marcel Duchamp’s Large Glass provides a detailed account of the artwork’s journey, encompassing its creation, exhibitions, breakages, repairs, and reconstructions. As a chronicle, the time lines offers insight into the complexities of authorship, authenticity, and conservation associated with an iconic artwork, revealing the evolving narrative surrounding it. Along the same lines, the concept of “original” comes also into question, as the various reconstructions of the Duchamp’s Large Glass by artists Ulf Linde and Richard Hamilton provoke discussions on authorship in art, as the points of departure for fabricating a copy of an artwork differ greatly, as there are clear divisions between fabricating a replication by following the visual information provided by the original work or realizing a reproduction following the conceptual basis of the work as the artists had documented it [34]. Therefore, both artists, through their different approaches, illuminate how replication can diverge based on whether one is adhering strictly to the physical and visual details of the original or whether one is engaging more deeply with the conceptual framework laid out by the original artist (Table 1).

Most importantly, Hamilton and Linde’s work highlights a key issue in contemporary art: a replica can either strive to mimic the exact visual appearance of the original, or it can aim to capture the original’s spirit and conceptual underpinnings. This distinction emphasizes the dual aspects of physical execution and conceptual interpretation in the reproduction of art. These considerations broaden the dialogue on how we perceive and value original works versus their replicas, challenging traditional views on creativity and the transmission of artistic ideas across different contexts and through different media. This is particularly relevant in the context of Duchamp, whose work fundamentally questioned the art world’s conventions and the role of the artist. Marcel Duchamp’s role in redefining authorship within the art world is underscored his introduction of the Readymade [34] and his provocative artistic strategies challenged the traditional boundaries between the artist’s intention and the audience’s reception. His works compel us to question not only who makes art, but how the identity of the maker affects our understanding and valuation of art itself. In the case of the replicas by Richard Hamilton and others, we see Duchamp’s influence echoing through their efforts. These replicas further the discourse on authorship by blurring the lines between creation and reproduction, between original and derivative. Ultimately, Duchamp’s legacy is that he expanded the framework of artistic authorship to include the ideas of selection, context, and presentation as artistic processes in their own right. This has paved the way for contemporary art to embrace a broader array of creative expressions, where the concept and context of a work can be as significant as the hand that crafted it. Thus, Duchamp did not just redefine what could be considered art; he redefined the very notion of being an artist, challenging subsequent generations to rethink the creative act [34].

In The Fate of the Animals, authenticity was preserved when Paul Klee carefully restored the painting by repainting damaged areas while lowering the tones to match the original. This ensured the emotional and aesthetic integrity of the piece remained intact, allowing viewers to connect with both its past and present forms. Similarly, Kintsugi, the Japanese art of mending broken pottery with gold, celebrates the object’s imperfections, highlighting the cracks rather than concealing them, thus preserving the object’s historical narrative. However, Marcel Duchamp’s The Large Glass (also known as The Bride Stripped Bare by Her Bachelors, Even) further exemplifies the complexities of authenticity in restoration. After the work was accidentally shattered during transport, Duchamp chose to leave the cracks as part of the artwork’s final form, viewing them as an integral part of its evolution. This decision reflected his emphasis on chance and transformation in art, adding another layer to the concept of authenticity by incorporating the artwork’s unintended changes into its completed state.

Further complicating the notion of authenticity, several reproductions of The Large Glass have been made. Notably, Richard Hamilton, a British artist, created a meticulous reproduction in 1965 after extensive consultation with Duchamp. Hamilton’s version captures both the original design and the cracks, thus maintaining the integrity of Duchamp’s decision to include the accidental damage. Additionally, in 1985, Swedish artist Ulf Linde also created a faithful reproduction of the work. These reproductions are considered authentic in the sense that they stay true to Duchamp’s original intentions and the work’s unique evolution, but they also raise questions about the boundaries of originality and authenticity in art restoration and reproduction. All three examples—Franz Marc’s The Fate of the Animals, the practice of Kintsugi, and Duchamp’s The Large Glass and its reproductions—demonstrate that authenticity in restoration and reproduction involves more than physical duplication. It’s about preserving the cultural and historical significance, the artist’s intent, and the artwork’s evolving narrative. These approaches allow contemporary audiences to engage with both the current condition of the artwork and its original essence, enriching their understanding of its journey and transformation over time.

In the context of the PERCEIVE project, authenticity of artworks is defined as the faithful reproduction and communication of the original visual and sensory characteristics, particularly focusing on their colour aspects. This includes accurately recreating how artworks originally appeared and might have been experienced in their original contexts, taking into account factors such as environmental lighting and the material conditions of the artifacts. The goal is to preserve not just the physical integrity of the artifacts but also the original sensory experiences they provided, ensuring that the representation in digital or restored formats remains true to the creator’s original intent and historical authenticity. PERCEIVE addresses several challenges in colour preservation across various mediums- It enhances methods for predicting and mitigating colour changes in paintings and works on paper due to aging and environmental factors. The project also develops strategies to maintain and accurately replicate original colours and designs in textiles like dresses and embroidery that are prone to fading. Additionally, it focuses on preserving the authenticity of colours in photographic collections, which often degrade over time, ensuring these images remain vibrant and true to their origins. Finally, the project delves into innovative preservation techniques for born-digital AR artworks, tackling the unique challenges of colour use and transparency in these contemporary formats.

How can we enable users to perceive the original appearance of artworks, thus enhancing the authenticity of the experience but also of the digital reproduction itself? Considering the “physical context” of objects requires to deal with components that have an impact or are impacted by it, such as “verification”, “embodiment” and “time”.

In PERCEIVE, we aim to develop colour restoration approaches as an attempt to visualise the original appearance of artworks that have partially or extensively lost their original colour. Colour change can manifest in several ways (colour loss, fading, alteration, etc.) and the different cases depend on the object typology as well as on various deteriorating factors. Among these factors, light exerts the most significant impact on the colouring materials, but often its impact is worsened due to the synergetic influence of other weathering parameters or conditions. In any case, although each of the case studies dictates a different approach towards the reconstruction of the original appearance, PERCEIVE adopts some basic concepts that are in common and refer to our aim to preserve Authenticity. Based on a set of assumptions, the restoration approaches should be guided by the artist’s technique and original intention in creating the artwork, although these are seldom fully known. By nature, such restoration attempts may bring a pluralistic solution to support multiple hypotheses, but they do not match the unique appearance of the original and are thus not authentic by themselves. Nonetheless, to preserve as much as possible the authenticity of the original, which is inextricably linked to the material substance of the object, the restored renderings should build upon residual traces of the original materials, i.e., pigments, colourants (preserved or faded) identifying them as a carrier, a persistent element of authenticity. In other words, we have to collect scientific data about the chemical composition and ageing properties in relation to various stress-inducing factors (light, humidity, temperature, etc.) for the residual materials in the artworks, where they exist.

Depending on the type of artworks, there is a different richness of residual information present. For example, in the case of textiles, the reverse side contains unfaded fibres that facilitate a restoration very close to the original [37, 38]. Paintings have materials that are protected from degradation factors on the edge, under the rebate of the frame [39, 40]. Although the materials under the frame might not be representative of the full pigment palette or composition of the painting, they still represent an additional piece of evidence for data collection or validation of the proposed restoration approaches. In the case of historical photos or film, such as autochromes and lenticular films, the relationship with authenticity is influenced not only by the fading of the dyes, but also by the medium of reproduction, such as the projector, as shown in Fig. 11. Thus, here we are dealing with a possible disconnection between the materiality of the artworks and its fruition means. As far as polychrome statues are concerned, the remaining traces might be very poor, and not even obviously localised. For this reason, it is recommended to investigate polychrome statues with spatial imaging techniques to identify possible areas where residual material is present [41].

The component of “physical context” is strictly connected with that of “verification”. In cases, in fact, where residual material is not present or is faint to provide reliable information for the original appearance (e.g., complete detachments in paintings, frescoes or polychrome statues), other contextual objects or other documentary or iconographic sources should be used as supporting evidence: archival records, recurrent art motifs depicted repeatedly, art history books with description of common materials, recipes, and practises typical of a certain art period. Fig. 12. shows the inverse relationship between the amount of remaining original material and the level of assumptions adopted in the design and development of the colour restoration tools.

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If even documentary sources are missing, then colour restoration methods relying on generative methods could be employed, as long as full reliability and interpretation process and the level of speculation are disclosed together with the results. Examples of such generative methods are “inpainting”, “colourization” and “outpainting”.

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Inpainting is an image restoration method, where partially missing content is reconstructed based on transfer of information from the regions neighbouring the missing area, or by learning visual representations typical to a specific type of dataset [42]. The missing content lacks information about the structure and colour, and the bigger the missing area the more challenging it is to accurately reconstruct it [43].

Colourization is the method of adding colour to monochrome images that have integral spatial content depicted in grayscale or sepia tones. From a chromatic point of view, the level of speculation is higher for colourization than for inpainting, as there are no intact coloured areas in the original image to give useful clues.

Outpainting, also known as “image extrapolation”, is a method that extends the limited visual field of a given image, and adds the non-captured context, by fully extrapolating the chromatic and structural information [44]. Hence, the creative freedom i.e. the level of speculation (which is inverse to the level of authenticity) is the highest in the case of outpainting, when referring to the two-dimensional image domain. Nonetheless, in the object domain, when extrapolation is desired, the composition of a material and its chromatic information can be revealed from the intact content. From this point of view, outpainting is more constrained in colour terms than it is in structural terms. Fig. 13. Shows a graphical representation of these three image restoration tasks and the level of speculation required for achieving colour and spatial reconstruction.

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The solutions of the colour restoration approaches should be iterative, and not closed-form, as they should allow for continuous improvements and refinements of the data-driven and learning-based algorithms, because of updated data collection experiments and feedback from quality assessments from the stakeholders.

Another important parameter to integrate in these restoration approaches is “time”, as it has also an impact on authenticity. Material aspects of the objects in fact vary across time. The signs of use and weathering are testimonies of the age and history, and they are proof of quality and resistance to damage [45]. The fragility of colour and its susceptibility to change, is in itself an evidence of authenticity. Through design strategies (element: “time flow”), that can include storytelling and interaction mechanisms, it is possible to highlight this component in the reconstruction of the original appearance of a coloured artwork. An example of such an approach can be the introduction of a timeline on which users could step back and forth, and progressively regain more complete versions of the original appearance or foreseen future additional damage. The concept of time and the experiential tracing of its effect on the materiality of artworks, step by step, through the perception of the change it brings to their original appearance, can be redemptive in contrast to the stressful demand for synchronisation of perception with the rapid technological evolution of everyday reality.

The aim of this approach remains to communicate knowledge to appreciate authenticity and share/enhance the sense of care and also manage (negotiate with) the change (back and forth in time) that is occurring in any case, (we cannot fully prevent it, maybe slow it down).

How can we design digital experiences that make users perceive them as authentic? To better understand how the authenticity conceptual framework (3.3) can be transformed into a proper application, we analyse here examples of digital or hybrid applications that can be taken as examples of authenticity. In some cases, they are just focused on a few components, in other cases they offer an experience that is more in line with our definition of “authenticity”. Following [3], we have tried to identify and represent how the components are distributed, using radar charts.