为什么CSS过滤器hue-rotate会产生奇怪的结果？

Question

我正在尝试使用CSS过滤器模拟Photoshop的"颜色叠加",同时这样做,发现CSS过滤器对颜色的操作与癫痫发作一致.

考虑一下颜色#FF0000.如果我们旋转它的色调120deg,我们应该得到#00FF00,并且240deg我们应该得到#0000FF.这是理智的领域.现在让我们进入CSS过滤器:

body { font: bold 99px Arial }
span { color: #F00; }
.daltonics-wont-notice {
    -webkit-filter: hue-rotate(120deg);
    filter: hue-rotate(120deg);
}
.precision-is-overrated {
    -webkit-filter: hue-rotate(240deg);
    filter: hue-rotate(240deg);
}

<span class="red">?</span>
<span class="daltonics-wont-notice">?</span>
<span class="precision-is-overrated">?</span>

什么应该#00FF00是#007100,而且应该是什么#0000FF是#0132FF.通过使用hue-rotate,色调,饱和度和亮度已设置为无意义的级别,跨浏览器.

我需要赶上Cthulhu并找出他编码的逻辑,以便我可以解决它.

这是一个与HSV或HSL无关的奇怪色彩空间吗？是否有可能将HSV,HSL或RGB坐标转换为这种异想天开的维度？它有名字吗？一个标准？邪教跟随？

Answer 1

我仍然无法相信这是跨浏览器.我的意思是,我一直在google搜索色彩空间,但没有找到任何地方他们的"色相"的定义是有道理的.他们将它完全从屁股中拉出来,作为镀锌愚蠢的一个巨大,尖刻的固体块.

无论哪种方式,我已经阅读了铭文,并仔细检查了神奇的咒语后,我已经制作了hue-rotate浏览器目前正在遭受的可怕破坏算法的javascript版本.

这是一个jsfiddle版本,这里是一个代码片段:

function calculate() {
    // Get the RGB and angle to work with.
    var color = document.getElementById('color').value;
    if (! /^[0-9A-F]{6}$/i.test(color)) return alert('Bad color!');
    var angle = document.getElementById('angle').value;
    if (! /^-?[0-9]+$/i.test(angle)) return alert('Bad angle!');
    var r = parseInt(color.substr(0, 2), 16);
    var g = parseInt(color.substr(2, 2), 16);
    var b = parseInt(color.substr(4, 2), 16);
    var angle = (parseInt(angle) % 360 + 360) % 360;
    
    // Hold your breath because what follows isn't flowers.
    
    var matrix = [ // Just remember this is the identity matrix for
        1, 0, 0,   // Reds
        0, 1, 0,   // Greens
        0, 0, 1    // Blues
    ];
    
    // Luminance coefficients.
    var lumR = 0.2126;
    var lumG = 0.7152;
    var lumB = 0.0722;
    
    // Hue rotate coefficients.
    var hueRotateR = 0.143;
    var hueRotateG = 0.140;
    var hueRotateB = 0.283;
    
    var cos = Math.cos(angle * Math.PI / 180);
    var sin = Math.sin(angle * Math.PI / 180);
    
    matrix[0] = lumR + (1 - lumR) * cos - lumR * sin;
    matrix[1] = lumG - lumG * cos - lumG * sin;
    matrix[2] = lumB - lumB * cos + (1 - lumB) * sin;
    
    matrix[3] = lumR - lumR * cos + hueRotateR * sin;
    matrix[4] = lumG + (1 - lumG) * cos + hueRotateG * sin;
    matrix[5] = lumB - lumB * cos - hueRotateB * sin;
    
    matrix[6] = lumR - lumR * cos - (1 - lumR) * sin;
    matrix[7] = lumG - lumG * cos + lumG * sin;
    matrix[8] = lumB + (1 - lumB) * cos + lumB * sin;
    
    function clamp(num) {
        return Math.round(Math.max(0, Math.min(255, num)));
    }
    
    var R = clamp(matrix[0] * r + matrix[1] * g + matrix[2] * b);
    var G = clamp(matrix[3] * r + matrix[4] * g + matrix[5] * b);
    var B = clamp(matrix[6] * r + matrix[7] * g + matrix[8] * b);
    
    // Output the result
    var result = 'The original color, rgb(' + [r,g,b] + '), '
               + 'when rotated by ' + angle + ' degrees '
               + 'by the devil\'s logic, gives you '
               + 'rgb(' + [R,G,B] + '). If I got it right.';
    document.getElementById('result').innerText = result;
}
// Listen for Enter key press.
['color', 'angle'].forEach(function(i) {
    document.getElementById(i).onkeypress = function(event) {
        var e = event || window.event, c = e.which || e.keyCode;
        if (c == '13') return calculate();
    }
});

body {
    font: 14px sans-serif;
    padding: 6px 8px;
}

input {
    width: 64px;
}

<p>
    This algorithm emulates the wierd, nonsensical and completely 
    idiotic <code>hue-rotate</code> CSS filter. I wanted to know
    how it worked, because it is out of touch with any definition
    of "hue" I've ever seen; the results it produces are stupid
    and I believe it was coded under extreme influence of meth,
    alcohol and caffeine, by a scientologist listening to Death Metal.
</p>
<span>#</span>
<input type="text" id="color" placeholder="RRGGBB">
<input type="text" id="angle" placeholder="degrees">
<button onclick="calculate()">Calculate</button>
<p id="result"></p>

请注意,在某些时候,他们可能会发现该算法是由一名实习生在4月1日编写的,他想对所有人进行恶作剧.他们甚至可以找到用于选择系数的骰子.

无论如何,了解所使用的随机逻辑有助于我解决它,这就是我这样做的原因.希望有人会对它进行调查,也许有一天我们会有hue-rotate浏览器附带的固定版本和公司.

作为奖励,万一它可以帮助任何人:这是棕褐色的计算方法:

var newPixel = {
    newRed:   oldRed * 0.393 + oldGreen * 0.769 + oldBlue * 0.189,
    newGreen: oldRed * 0.349 + oldGreen * 0.686 + oldBlue * 0.168,
    newBlue:  oldRed * 0.272 + oldGreen * 0.534 + oldBlue * 0.131,
};