C中快速,优化和准确的RGB < - > HSB转换代码

#include<stdio.h>
#include <stdlib.h>
#include <math.h>

typedef struct {
    float h;
    float s;
    float b;
} HSB;

typedef struct {
    float r;
    float g;
    float b;
} RGB;

HSB rgb2hsb(RGB in)
{
    float hue, saturation, brightness;
    float r = in.r;
    float g = in.g;
    float b = in.b;
    float cmax = (r > g) ? r : g;
    if (b > cmax) cmax = b;
    float cmin = (r < g) ? r : g;
    if (b < cmin) cmin = b;
    float delta = cmax - cmin;
    brightness = cmax;
    if (delta == 0) {
        hue = 0;
        saturation = 0;
    } else {
        saturation = delta / cmax;
        if (r == cmax)
            hue = (g - b) / delta;
        else if (g == cmax)
            hue = 2 + (b - r) / delta;
        else
            hue = 4 + (r - g) / delta;
        hue *= 60;
        if (hue < 0)
            hue += 360;
    }
    HSB out;
    out.h = hue;
    out.s = saturation;
    out.b = brightness;
    return out;
}

RGB hsb2rgb(HSB in)
{
    float hue = in.h;
    float saturation = in.s;
    float brightness = in.b;
    float h = hue / 60;
    int i = floor(h);
    float f = h - i;
    float p = brightness * (1 - saturation);
    float q = brightness * (1 - saturation * f);
    float t = brightness * (1 - saturation * (1 - f));
    float r, g, b;
    switch (i) {
        case 0:
            r = brightness;
            g = t;
            b = p;
            break;
        case 1:
            r = q;
            g = brightness;
            b = p;
            break;
        case 2:
            r = p;
            g = brightness;
            b = t;
            break;
        case 3:
            r = p;
            g = q;
            b = brightness;
            break;
        case 4:
            r = t;
            g = p;
            b = brightness;
            break;
        default:
            r = brightness;
            g = p;
            b = q;
            break;
    }
    RGB out;
    out.r = r;
    out.g = g;
    out.b = b;
    return out;
}

int main()
{
    RGB rgb;
    HSB hsb;
    rgb.r = 255;
    rgb.g = 0;
    rgb.b = 0;
    hsb = rgb2hsb(rgb);
    printf("HSB: h = %.2f, s = %.2f, b = %.2f\n", hsb.h, hsb.s, hsb.b);
    hsb.h = 120;
    hsb.s = 1;
    hsb.b = 1;
    rgb = hsb2rgb(hsb);
    printf("RGB: r = %.2f, g = %.2f, b = %.2f\n", rgb.r, rgb.g, rgb.b);
    return 0;
}