toHSV

toHSV refers to the transformation that converts color data from the RGB color space to the HSV color space. It is commonly used in image processing and computer vision for color-based segmentation, filtering, and tracking, because HSV separates color information (hue) from lightness or intensity (value). The term may appear as a function or method name in libraries, or as a description of a general conversion process.

Input and output: A toHSV operation can be applied to a single color triple (R, G, B) or to an image with three channels. RGB values may be in the range 0–255 (integer) or 0–1 (floating point). The output is a corresponding HSV representation, with components H (hue), S (saturation), and V (value). Hue encodes color type, saturation expresses colorfulness, and value represents brightness.

Algorithm: Let max = max(R, G, B), min = min(R, G, B), and delta = max − min. V is set to max. S is 0 if max equals 0; otherwise S = delta / max. If delta equals 0, hue is undefined and is often set to 0. Otherwise, determine hue from the channel that is maximum: if max equals R, H = (G − B) / delta; if max equals G, H = 2 + (B − R) / delta; if max equals B, H = 4 + (R − G) / delta. Multiply H by 60 to convert to degrees; if H is negative, add 360. When using normalized inputs, S and V may be in [0,1] and H in [0,1] (or degrees, depending on convention).

Representation and notes: Different libraries adopt different ranges. Some return H in [0,179], S and V in [0,255] for 8-bit images, others use H in [0,360) with S and V in [0,1]. Grayscale images typically have S = 0 and an arbitrary H. The toHSV conversion is deterministic but hue interpretation depends on the chosen range and data type.