Similar to the human eye, digital camera sensors have their own unique corresponding curves for blue, green and red(see figure 1). The sensitivity of digital cameras is different from the human eye, so the way digital cameras capture color is different. The European Broadcasting Union (EBU) created the Television Illumination Consistency Index (TLCI-2012) for digital cameras to replace the CRI.
Figure 1: Color response curves of the human eye and a CCD camera
High TLCI LED lamps help filmmakers, broadcasters and digital creators capture scenes in a consistent light, reducing or eliminating costly color corrections in post-processing. Figure 2 shows the toning effort required by a professional colorist for different lighting scenarios with different level of TLCI. It can be seen that under TLCI> 90 scene will allow a professional colorist to easily make color corrections, whereas in TLCI>95 no need for color correction at all in all but the most demanding scenarios. AIKO’s LED sports lights are available in 90+ TLCI and 95+ TLCI to meet the different needs of customers.
Figure 2: The effort and skill needed (right) to properly color correct photography or videography illuminated by lights of a typical TLCI value of the scale on the left
Using a simple HD digital camera, we can easily demonstrate the color rendering difference under 90 CRI and 95 TLCI. Figure 3 shows a standard 90 CRI illuminated scene at 1500 lux. Figure 4 shows the same scene illuminated by a 5700K 95 TLCI 95 CRI. It is easy to see the differences in the fabric samples on the far left, which have clearer whites and more vivid cyan and light blue colors. For comparison, Figure 5 shows the same scene illuminated with the same lux by a standard 70 CRI LED.
Figure 3: Scene illuminated by a standard 90 CRI at 1500 lux
Figure 4: Same scene illuminated by a 5700K 95 TLCI 95 CRI
Figure 5: Same scene illuminated with the same lux by a standard 70 CRI LED
If you use photo editing software to zoom in on these fabric samples (see Figure 6), the digital RGB value differences will be revealed between 90 CRI and 95 TLCI lighting. The RGB values in the white sample are closer to pure white (255, 255, 255), especially in the blue component. In the cyan sample, RGB values showed better saturation in all three channels, but the biggest difference was in the blue component. This difference can be expected, as the 95 TLCI LED fills the cyan gap better than the standard 90 CRI LED. The red channel also shows a significant increase in saturation due to the wider and longer wavelength red component of the 95 TLCI LED