Corona Ideas Portal
The online platform for Corona users to submit, vote, and collaborate on creative suggestions.
The online platform for Corona users to submit, vote, and collaborate on creative suggestions.
Many paint and color manufacturers, such as RAL and Farrow & Ball, provide accurate LAB measurements for their color systems. However, many of these colors do not fit neatly into the sRGB color space. As a result, the sRGB values provided on their websites are often clipped — for example, a true color might be listed as (r255, g32, b66), even though the original, unclipped conversion would have an r value exceeding 255.
Although the total energy (albedo) remains within a physically plausible range, individual color channels are still capped at 255. Currently, I work around this limitation by manually converting LAB to XYZ to linear RGB, then inputting the unclipped values into the solid HDR color box of the CoronaColor map, selecting the sRGB color space from the dropdown. While theoretically effective, this workflow is tedious.
Corona could make a significant improvement here by supporting designers and architects more directly. Adding native support for major color systems like RAL, Farrow & Ball and Pantone based on their LAB specifications would be a valuable step forward.
Even with accurate LAB values, the results are still not entirely precise. This is because LAB measurements typically include both diffuse and specular reflections in a single reading. Even highly diffuse materials exhibit some level of specular reflection—around 4% at F0—depending on their index of refraction (IOR) and surface geometry.
While this is less of an issue for bright colors—since tonemapping compresses highlights and naturally fades them—it becomes significant for darker colors. For example, the total albedo of a charcoal-like material is around 4–5%. Subtracting the specular contribution from that would leave you with a base color approaching RGB 0, which can be problematic.
Still, adopting such an approach would mark a major improvement toward more physically accurate workflows, offering a strong and reliable alternative to traditional artistic methods.