Comparative Analysis of Image Quality Assessment Between Digital Signal-to-Noise Ratio (SNR) Camera and Smartphone...

Background The growing sophistication of smartphone cameras has prompted enquiry into their suitability as alternatives to digital single-lens reflex (DSLR) cameras for clinical dental photography. This study compared the image quality of a DSLR camera and two smartphone systems, each fitted with an identical macro lens, for intraoral dental photography using objective colorimetric and signal-to-noise ratio (SNR) metrics. Methods Thirty dental students were enrolled in this comparative, cross-sectional study. Standardised intraoral photographs were captured across seven views using three camera systems: a DSLR with a Canon 100 mm macro lens and ring flash (Canon Inc., Tokyo, Japan), a Samsung smartphone (Samsung Electronics Co., Ltd., Suwon, South Korea), and an Apple iPhone (Apple Inc., Cupertino, CA), the latter two fitted with an identical custom Sony 100 mm macro lens and twin flash (Sony Group Corporation, Tokyo, Japan). CIELAB colour space (CIE L*, a*, and b*) values were recorded in Adobe Photoshop (Adobe Inc., San Jose, CA), and the total colour difference (ΔE) was calculated. SNR was computed in MATrix LABoratory (MATLAB) (MathWorks, Natick, MA) from a standardised background region. One-way analysis of variance (ANOVA) and Tukey honestly significant difference (HSD) post hoc tests were applied (significance: p < 0.05). Results The DSLR produced the most consistent colour rendition and served as the colour reference standard. The mean ΔE between the DSLR and the smartphones was comparable for the two devices (25.63 ± 8.62 for Samsung; 25.98 ± 9.56 for iPhone; p = 0.486), and both values substantially exceeded the clinically acceptable threshold of ΔE ≤ 2.0. Mean lightness (L*) was markedly lower for the DSLR (25.24) than for the Samsung (47.47) and iPhone (47.59) systems (p < 0.001). A warm, yellow-shifted smartphone bias was most evident in the frontal shade-matching view. SNR was highest for the iPhone, followed by the Samsung, and lowest for the DSLR, a reversal attributable to artificial-intelligence-driven computational noise reduction in the smartphones. Conclusions The DSLR remains the reference standard for colour-critical intraoral dental photography. The elevated SNR recorded for the smartphones reflected computational noise reduction rather than superior image fidelity. Neither smartphone achieved clinically acceptable colorimetric agreement with the DSLR, nor did brand materially influence this outcome once the optical configuration was standardised. Standardised calibration protocols warrant further investigation before smartphone systems are adopted for colour-critical applications.