Why doesn't this Javascript RGB to HSL code work?

Question

I found this RGB to HSL script over at http://www.mjijackson.com/2008/02/rgb-to-hsl-and-rgb-to-hsv-color-model-conversion-algorithms-in-javascript. I can't find any other small decent ones. The issue is that this code doesn't even really work. Would anybody know why? (I don't know a bit of color math, but maybe it's returning the complementary?)

function rgbToHsl(r, g, b){
    r /= 255, g /= 255, b /= 255;
    var max = Math.max(r, g, b), min = Math.min(r, g, b);
    var h, s, l = (max + min) / 2;

    if(max == min){
        h = s = 0; // achromatic
    }else{
        var d = max - min;
        s = l > 0.5 ? d / (2 - max - min) : d / (max + min);
        switch(max){
            case r: h = (g - b) / d + (g < b ? 6 : 0); break;
            case g: h = (b - r) / d + 2; break;
            case b: h = (r - g) / d + 4; break;
        }
        h /= 6;
    }

    return [h, s, l];
}

Edit: when I run rgbToHsl(126,210,22) it's giving me [ .24, .81, .45 ], which is the HSL for an orange color.

Answer 1

The resulting HSV array has to be interpreted as three fractions. For some programs, if you want to express HSV as integers, you multiply the "H" value by 360 and the "S" and "V" values by 100. The HSV value you quote for your green shade RGB[126, 210, 22] is HSV [87, 81, 45] in integers. You could change the function to return such integers if you want to:

function rgbToHsl(r, g, b){
    r /= 255, g /= 255, b /= 255;
    var max = Math.max(r, g, b), min = Math.min(r, g, b);
    var h, s, l = (max + min) / 2;

    if(max == min){
        h = s = 0; // achromatic
    }else{
        var d = max - min;
        s = l > 0.5 ? d / (2 - max - min) : d / (max + min);
        switch(max){
            case r: h = (g - b) / d + (g < b ? 6 : 0); break;
            case g: h = (b - r) / d + 2; break;
            case b: h = (r - g) / d + 4; break;
        }
        h /= 6;
    }

    return [Math.floor(h * 360), Math.floor(s * 100), Math.floor(l * 100)];
}

[edit] that said, it's still giving me something with a brightness ("L" or "V") that's considerably too dark; Gimp says that the HSV value should be [90, 80, 82], or in fractional terms [.20, .80, .82].

[another edit] well one problem could be that HSL and HSV are different schemes ... still looking around.

OK in case anybody wants RGB to HSV (like you'd see in Gimp for example) here's a version of that:

function rgbToHsv(r, g, b) {
    var
        min = Math.min(r, g, b),
        max = Math.max(r, g, b),
        delta = max - min,
        h, s, v = max;

    v = Math.floor(max / 255 * 100);
    if ( max != 0 )
        s = Math.floor(delta / max * 100);
    else {
        // black
        return [0, 0, 0];
    }

    if( r == max )
        h = ( g - b ) / delta;         // between yellow & magenta
    else if( g == max )
        h = 2 + ( b - r ) / delta;     // between cyan & yellow
    else
        h = 4 + ( r - g ) / delta;     // between magenta & cyan

    h = Math.floor(h * 60);            // degrees
    if( h < 0 ) h += 360;

    return [h, s, v];
}

Answer 2

Function below converts RGB color into Hue Saturation Brightness color like Photoshop color picker, results are in the ranges:

• Hue 0-360 (degrees)
• Saturation: 0-100 (%)
• Brightness: 0-100 (%)

I still don't understand why people use the term HSV (Hue Saturation Value) instead of HSB (Hue Saturation Brightness), anyway it's a matter fo terminology, the results are the same

   //Converts to color HSB object (code from here http://www.csgnetwork.com/csgcolorsel4.html with some improvements)
   function rgb2hsb(r, g, b)
   {    
    r /= 255; g /= 255; b /= 255; // Scale to unity.   
    var minVal = Math.min(r, g, b),
    maxVal = Math.max(r, g, b),
    delta = maxVal - minVal,
    HSB = {hue:0, sat:0, bri:maxVal},
    del_R, del_G, del_B;

    if( delta !== 0 )
    {
        HSB.sat = delta / maxVal;
        del_R = (((maxVal - r) / 6) + (delta / 2)) / delta;
        del_G = (((maxVal - g) / 6) + (delta / 2)) / delta;
        del_B = (((maxVal - b) / 6) + (delta / 2)) / delta;

        if (r === maxVal) {HSB.hue = del_B - del_G;}
        else if (g === maxVal) {HSB.hue = (1 / 3) + del_R - del_B;}
        else if (b === maxVal) {HSB.hue = (2 / 3) + del_G - del_R;}

        if (HSB.hue < 0) {HSB.hue += 1;}
        if (HSB.hue > 1) {HSB.hue -= 1;}
    }

    HSB.hue *= 360;
    HSB.sat *= 100;
    HSB.bri *= 100;

    return HSB;
   }

Usage example:

var hsb = rgb2hsb(126,210,22);
alert("hue = " + hsb.hue + "saturation = " + hsb.sat + "brightness = " + hsb.bri);

Answer 3

sttp://msdn.microsoft.com//msdn.microsoft.com/en-us/library/office/hh185007%28v=office.14%29.aspx" Rel="nofollow"> 여기 ...에 JavaScript 함수 GeneraCodicicetagcode는 중요합니다. 후세를 위해 여기에 그것을 복사하자.

function retrieveListItems() {

    var clientContext = new SP.ClientContext(siteUrl);
    var oList = clientContext.get_web().get_lists().getByTitle('Announcements');

    var camlQuery = new SP.CamlQuery();
    camlQuery.set_viewXml('<View><Query><Where><Geq><FieldRef Name=\'ID\'/>' + 
    '<Value Type=\'Number\'>1</Value></Geq></Where></Query><RowLimit>10</RowLimit></View>');
    this.collListItem = oList.getItems(camlQuery);

    clientContext.load(collListItem);

    clientContext.executeQueryAsync(Function.createDelegate(this, this.onQuerySucceeded), Function.createDelegate(this, this.onQueryFailed));        
}

.

해당 코드에서 retrieveListItems()를 목록의 제목으로 바꿉니다.

CAML 쿼리는 기본적으로 목록의 항목 수를 기본적으로 필터링 할 수 있습니다 (수백만에있을 수 있습니다). 그래서 당신을 위해 그것을 깰 수 있습니다 :

<View>
    <Query>
        <Where>
            <Geq>
                <FieldRef Name='ID'/> 
                <Value Type=\'Number\'>1</Value>
            </Geq>
        </Where>
    </Query>
    <RowLimit>10</RowLimit>
</View>

.

이 CAML 쿼리는 목록 항목 ID (목록에 대한 목록)가 1보다 큰 처음 10 항목을 반환합니다. CAML에 대한 추가 정보는이 상자의 범위가 조금 벗어 났지만 시작을 돕는 링크가 있습니다. < / P>

• Caml 쿼리 스키마 / li>
• Caml 쿼리 도구
• Microsoft CAML 쿼리 자습서