Javascript 准确地将 HSB/HSV 颜色转换为 RGB

Question

我需要准确地将 HSB 转换为 RGB，但我不确定如何解决将小数转换为整数而不四舍五入的问题。这是我在颜色选择器库中的当前功能:

HSBToRGB = function (hsb) {

    var rgb = { };
    var h = Math.round(hsb.h);
    var s = Math.round(hsb.s * 255 / 100);
    var v = Math.round(hsb.b * 255 / 100);

        if (s == 0) {

        rgb.r = rgb.g = rgb.b = v;
        } else {
        var t1 = v;
        var t2 = (255 - s) * v / 255;
        var t3 = (t1 - t2) * (h % 60) / 60;

            if (h == 360) h = 0;

                if (h < 60) { rgb.r = t1; rgb.b = t2; rgb.g = t2 + t3 }
                else if (h < 120) { rgb.g = t1; rgb.b = t2; rgb.r = t1 - t3 }
                else if (h < 180) { rgb.g = t1; rgb.r = t2; rgb.b = t2 + t3 }
                else if (h < 240) { rgb.b = t1; rgb.r = t2; rgb.g = t1 - t3 }
                else if (h < 300) { rgb.b = t1; rgb.g = t2; rgb.r = t2 + t3 }
                else if (h < 360) { rgb.r = t1; rgb.g = t2; rgb.b = t1 - t3 }
                else { rgb.r = 0; rgb.g = 0; rgb.b = 0 }
        }

    return { r: Math.round(rgb.r), g: Math.round(rgb.g), b: Math.round(rgb.b) };

如您所见，此函数的不准确性来自 Math.round

Answer 1

来自 Parthik Gosar的 link在 this comment稍作修改，让您独立输入每个值或作为一个对象一次性输入

/* accepts parameters
 * h  Object = {h:x, s:y, v:z}
 * OR 
 * h, s, v
*/
function HSVtoRGB(h, s, v) {
    var r, g, b, i, f, p, q, t;
    if (arguments.length === 1) {
        s = h.s, v = h.v, h = h.h;
    }
    i = Math.floor(h * 6);
    f = h * 6 - i;
    p = v * (1 - s);
    q = v * (1 - f * s);
    t = v * (1 - (1 - f) * s);
    switch (i % 6) {
        case 0: r = v, g = t, b = p; break;
        case 1: r = q, g = v, b = p; break;
        case 2: r = p, g = v, b = t; break;
        case 3: r = p, g = q, b = v; break;
        case 4: r = t, g = p, b = v; break;
        case 5: r = v, g = p, b = q; break;
    }
    return {
        r: Math.round(r * 255),
        g: Math.round(g * 255),
        b: Math.round(b * 255)
    };
}

此代码需要 0 <= h, s, v <= 1 ，如果您使用的是度数或弧度，请记住将它们分开。

返回的0 <= r, g, b <= 255四舍五入到最接近的整数。如果您不希望出现此行为，请删除 Math.round s 来自返回的对象。

---

反之(划分较少)

/* accepts parameters
 * r  Object = {r:x, g:y, b:z}
 * OR 
 * r, g, b
*/
function RGBtoHSV(r, g, b) {
    if (arguments.length === 1) {
        g = r.g, b = r.b, r = r.r;
    }
    var max = Math.max(r, g, b), min = Math.min(r, g, b),
        d = max - min,
        h,
        s = (max === 0 ? 0 : d / max),
        v = max / 255;

    switch (max) {
        case min: h = 0; break;
        case r: h = (g - b) + d * (g < b ? 6: 0); h /= 6 * d; break;
        case g: h = (b - r) + d * 2; h /= 6 * d; break;
        case b: h = (r - g) + d * 4; h /= 6 * d; break;
    }

    return {
        h: h,
        s: s,
        v: v
    };
}

此代码将输出 0 <= h, s, v <= 1 , 但这次需要任何 0 <= r, g, b <= 255 (不需要是整数)

---

为了完整性，

function HSVtoHSL(h, s, v) {
    if (arguments.length === 1) {
        s = h.s, v = h.v, h = h.h;
    }
    var _h = h,
        _s = s * v,
        _l = (2 - s) * v;
    _s /= (_l <= 1) ? _l : 2 - _l;
    _l /= 2;

    return {
        h: _h,
        s: _s,
        l: _l
    };
}

function HSLtoHSV(h, s, l) {
    if (arguments.length === 1) {
        s = h.s, l = h.l, h = h.h;
    }
    var _h = h,
        _s,
        _v;

    l *= 2;
    s *= (l <= 1) ? l : 2 - l;
    _v = (l + s) / 2;
    _s = (2 * s) / (l + s);

    return {
        h: _h,
        s: _s,
        v: _v
    };
}

所有这些值都应该在 0 范围内至 1 .对于 HSL<->RGB 通过HSV。