Assessing RGB Color Reliability via Simultaneous Comparison with Hyperspectral Data on Pantone^® Fabrics

Accurate color property measurements are critical for advancing artificial vision in real-time industrial applications. RGB imaging remains highly applicable and widely used due to its practicality, accessibility, and high spatial resolution. However, significant uncertainties in extracting chromatic information highlight the need to define when conventional digital images can reliably provide accurate color data. This work simultaneously compares six chromatic properties across 700 Pantone^® TCX fabric samples, using optical data acquired simultaneously from both hyperspectral (HSI) and digital (RGB) cameras. The results indicate that the accurate interpretation of optical information from RGB (sRGB and REC2020) images is significantly influenced by lightness (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mrow><mi>L</mi></mrow><mrow><mo>*</mo></mrow></msup></mrow></semantics></math></inline-formula>) values. Samples with bright and unsaturated colors (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mrow><mi>L</mi></mrow><mrow><mo>*</mo></mrow></msup><mo>></mo></mrow></semantics></math></inline-formula> 50) reach ratio-to-performance-deviation (RPD) values above 2.5 for four properties (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mrow><mi>L</mi></mrow><mrow><mo>*</mo></mrow></msup><mo>,</mo><mo> </mo><msup><mrow><mi>a</mi></mrow><mrow><mo>*</mo></mrow></msup><mo>,</mo><mo> </mo><msup><mrow><mi>b</mi></mrow><mrow><mo>*</mo></mrow></msup></mrow></semantics></math></inline-formula> <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow><mi>h</mi></mrow><mrow><mi>a</mi><mi>b</mi></mrow></msub></mrow></semantics></math></inline-formula>), indicating a good correlation between HSI and RGB information. Absolute color difference comparisons (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow><mo>∆</mo><mi>E</mi></mrow><mrow><mi>a</mi></mrow></msub></mrow></semantics></math></inline-formula>) between HSI and RGB images yield values exceeding 5.5 units for red-yellow-green samples and up to 9.0 units for blue and purple tones. In contrast, relative color differences (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow><mo>∆</mo><mi>E</mi></mrow><mrow><mi>r</mi></mrow></msub></mrow></semantics></math></inline-formula>) comparisons show a significant decrease, with values falling below 3.0 for all lightness values, indicating the practical equivalence of both methodologies according to the Two One-Sided Test (TOST) statistical analysis. These results confirm that RGB imagery achieves reliable color consistency when evaluated against a practical reference.