Color model with hue, saturation, and lightness — standard in web/software but less practical for grading than HSV or HSI.
In grading and VFX work, colorists regularly encounter the HSL model — Hue, Saturation, Lightness. It organizes color differently than the RGB model, which cameras and monitors speak: Instead of mixing red, green, and blue channels, HSL separates color information into three orthogonal dimensions. Hue sits on a 360-degree circle, Saturation controls intensity from zero (gray) to 100 percent (full color), and Lightness determines whether the color tends towards white or black.
This sounds practical — and for certain tasks, it is. HSL dominates web and UI design because you work intuitively with sliders there. However, when filming, the problem quickly becomes apparent: HSL uses a cylindrical coordinate system that does not linearly correspond to human color perception. The Lightness axis lacks correct luma weighting like in professional color spaces — it treats red, green, and blue mathematically equally, even though the eye perceives green as more dominant. In grading, this leads to unintuitive behavior: If I increase the Lightness of a saturated color, it quickly appears exaggerated or falsified. Therefore, colorists prefer to work with HSV (Hue, Saturation, Value), which directly links brightness to the highest RGB value and feels better on set and in editing.
HSL appears in the film workflow primarily in two contexts: firstly, when using correction software like DaVinci Resolve and wanting to isolate specific color ranges — here, HSL-based curves or wheels offer quick control. Secondly, when VFX supervisors or compositors work with web-based tools or Python scripts and need to adopt HSL values from design documents or color specifications. This then requires a conscious conversion to linear RGB or to the working color space to avoid surprises in the final render.
In daily practice: HSL is a useful concept for quick color conversions and for communication with designers, but it is not a primary grading tool. Those working on set or in color correction will learn HSL more theoretically; the real work happens in RGB linear spaces or with luma-based models like YUV or with the wheels and curves of professional grading software.