2020 journal article

Accurate colorimetric images using LEDs


author keywords: color image processing; colorimetric; accurate color
Source: Web Of Science
Added: November 16, 2020

It is well known that more than three or four spectral measurements are required for accurate measurement of color under arbitrary illumination. Previous work has shown 6 to 10 measurements can yield accurate results on average, but with significant numbers of errors above the threshold of obvious visual detection. We demonstrate an imaging system (LED box) consisting of a monochrome camera, multiple LED illumination in a diffuse reflecting chamber that produces excellent color capture in perceptual quality measured in ΔE00. We evaluate this system with respect to practical applications with emphasis on textile quality assessment. Our system of 12 LEDs produces average and maximum training ΔE00 errors around 0.7 and 2.4, respectively; and average and maximum testing ΔE00 errors around 1.5 and 5.0, respectively. This performance exceeds that of reported colorimetric camera systems, except highly specialized configurations. We find that the stability of the system to LED variability under operating conditions is good. We show that pseudoinverse estimate produces better results than the MMSE estimate under actual operating conditions.