2.5. Image analysis and color measurement
The digital system used (Fig. 2) consisted of the
following elements:
(i) Lighting system. Samples were illuminated using two
parallel fluorescent lamps (Philips, TL-D Deluxe,
Natural Daylight, 18W/965) with a color temperature
of 6500K and a color-rendering index (Ra) close to
95%. Both lamps (60 cm long) were situated 35 cm
above the sample and at an angle of 451 with the
sample. Additionally, light diffusers covering each
fluorescent lamp and electronic ballast assured a
uniform light distribution.