## 1 Introduction  
Display-to-camera (D2C) communication [1; 2; 3] is an application of visible light communication (VLC) [4], in which an LCD and a camera sensor can communicate for device-to-device communication. Owing to the vast popularity of mobile devices and the widespread availability of displays, D2C communication is the next promising candidate with the potential to replace conventional approaches, such as QR codes and 2D barcodes. In D2C communication, information is encoded on the display screens of smartphones, laptops, advertisement boards, etc. Another device with a camera sensor (such as a smartphone) can capture the screen and decode data using image analysis. Conventional approaches require space and are obtrustive to the human eye. For instance, a QR code placed at the corner of a commercial advertisement is not visually aesthetic and produces distractions. Second, the data transmission capability of a QR code, such as the URL of a product's homepage, is extremely limited. Although increasing attention is paid to embedding images into QR codes to mitigate the above limitations [5; 6; 7], a new approach of embedding the data directly into the image frames of a display might completely replace the conventional approach. This can be attributed to the inherent advantages of D2C communication, such as higher data rates and unobtrusiveness of the display to normal human viewers. D2C communication has the potential to enable a wide range of applications in areas, such as security [8; 9], healthcare, and smart homes [10; 11]. A key advantage of D2C communication is its security. Because transmission occurs through light, it is much more difficult to intercept the signal compared to other wireless communication methods such as radio frequency or Bluetooth. This makes D2C communication particularly useful for applications such as mobile banking, access-control systems, and healthcare devices. In addition, D2C communication can enable new types of interactive experiences. For example, it can be used to allow users to interact with displays in public spaces by simply pointing their cameras at the screen. This could open new possibilities for interactive advertising, digital signage, and other types of public information displays [12]. Approaches for embedding data into image frames can be broadly divided into two categories: spatial domain and spectral domain embedding. For example, in the work of [PERSON] et al. [13], information bits are carried with spatially complementary visual patterns assembled into complementary temporal frames. This study uses the concept of complementary frames displayed at a high frame rate to ensure a normal viewing experience. HiLight [14] encodes data into pixel translucency changes for any screen content using an alpha channel. Here, an additional image layer (a black matte, fully transparent) is created on top of the content image layer, which is dedicated to data communication and is referred to as the communication layer. To transmit the data, the communication layer was divided into grids, and data were encoded into the pixel translucency change of each grid without affecting the user's viewing experience. By contrast, data can be embedded in the spectral domain of an image [15]. Spectral-domain data embedding captures the characteristics of the human visual system better [16]. In other words, spectral domain techniques can take advantage of the fact that the human eye perceives different parts of the spectrum differently, allowing selective embedding in less perceptually important regions. In addition, spectral domain techniques can be more robust to compression and other signal processing algorithms that often affect the spatial domain more strongly than the spectral domain [17]. One of the spectral-domain data embedding approaches is display field communication (DFC) [18; 19], where data are embedded into the frequency domain of an image by employing the properties associated with the frequency coefficients of an image.