###### Abstract
The advancement of photography and computing has led to the development of image-based digital shade guides, which serve as an effective alternative to contact-type instrumental shade-matching devices [6; 10; 11; 12; 13] in improving shade-matching accuracy [14; 15]. High resolution digital photographs enable the reproduction of the entire tooth color spectrum and unique tooth surface characteristics [16], thus facilitating communication between clinicians and technicians [12; 17]. In previous studies, digital single-lens reflex (DSLR) cameras have been commonly used for capturing high resolution images in dental shade matching [12; 17; 18; 19]. Nevertheless, there is a growing trend toward mirrorless camera systems, which offer advantages such as greater compactness, lighter weight, and faster autofocus, along with improved light exposure optimization [20]. These mirrorless cameras, equipped with high resolution sensors, excel in capturing fine details and textures within the oral cavity [21]. Key improvements in image quality include back-illuminated sensors that enhance performance in low-light conditions and in-body image stabilization that minimizes blurriness by stabilizing across multiple axes [20]. Alternatively, smartphone cameras, which are highly accessible, have gained popularity in dental photography. Improvements in smartphone camera technology have significantly enhanced image quality, making them comparable to those taken by DSLR cameras [22; 23]. In a study by [PERSON] et al. [24], the linear measurements of plaster models photographed with both a DSLR and a smartphone camera were found to have no statistically significant differences. Smartphone cameras with accurate edge positioning and radiometry allow for good quality and well-defined images with correct color reproduction as compared to a DSLR camera [25]. [PERSON] et al. [6] also found that when equipped with suitable light-correction filters, smartphones provided shade selection results comparable to those achieved with digital cameras for color assessment of ceramic crowns. The CIELAB system is widely used in dentistry because of its adaptive chromatic basis, which facilitates quantification of reflected light [26; 27; 28]. This system helps to determine the color coordinates L\({}^{*}\) (luminosity, from black to white), a* (chromaticity along the red-green axis), and b* (chromaticity along the yellow-blue axis) [29]. The color difference (\(\Delta\)E) formula has been adopted as the standard to measure the color difference between two objects [30]. CIEDE2000 color difference (\(\Delta\)E\({}_{00}\)), as an improved version of \(\Delta\)E\({}_{\text{ab}}\), is well recommended by the International Commission on Illumination (CIE) for total color difference computation because of its high accuracy and repeatability [31]. In dentistry, color differences (\(\Delta\)E) are quantitatively assessed against established thresholds to determine clinical relevance. AT is a magnitude of color difference that is acceptable for the aesthetic outcome, while PT refers to the smallest color difference the human eye can detect [32]. Based on a comprehensive review by [PERSON] et al. [33], PT values typically range from 0.8 to 1.7, while AT values vary from 1.8 to 3.7, depending on variables such as observer type, lighting conditions, and material characteristics. Despite this range, the values \(\Delta\)E\({}_{00}\) = 0.8 for PT and \(\Delta\)E\({}_{00}\) = 1.8 for AT are widely accepted as standard reference points in controlled in vitro studies involving dental ceramics. To date, there is a lack of studies investigating the potential use of image-based digital shade guides in dental shade matching. Hence, this study aims to construct two image-assisted digital versions of the VITA Linearguide, using calibrated images of its shade tabs captured with a mirrorless camera (MC-DSG) and smartphone camera (SC-DSG), respectively.