HSL to RGB color conversion

Question

I am looking for an algorithm to convert between HSL color to RGB  It seems to me that HSL is not very widely used so I am not having much luck searching for a converter

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Here s a fast  super-simple  branchless version in GLSL   vec3 hsl2rgb  vec3 c         vec3 rgb   clamp abs mod c x 6 0   vec3 0 0  4 0  2 0   6 0 -3 0 -1 0  0 0  1 0       return c z   c y    rgb-0 5   1 0-abs 2 0 c z-1 0        Doesn t get much shorter than that      Link to the original proof-of-concept   https   www shadertoy com view XljGzV   Disclaimer  not my code

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Garry Tan posted a Javascript solution on his blog  which he attributes to a now defunct mjijackson com  but is archived here and the original author has a gist - thanks to user2441511     The code is re-posted below   HSL to RGB          Converts an HSL color value to RGB  Conversion formula    adapted from http   en wikipedia org wiki HSL color space     Assumes h  s  and l are contained in the set  0  1  and    returns r  g  and b in the set  0  255          param    number   h       The hue     param    number   s       The saturation     param    number   l       The lightness     return   Array            The RGB representation     function hslToRgb h  s  l       var r  g  b       if s    0           r   g   b   l     achromatic      else          var hue2rgb   function hue2rgb p  q  t               if t  lt  0  t    1              if t  gt  1  t -  1              if t  lt  1 6  return p    q - p    6   t              if t  lt  1 2  return q              if t  lt  2 3  return p    q - p     2 3 - t    6              return p                     var q   l  lt  0 5   l    1   s    l   s - l   s          var p   2   l - q          r   hue2rgb p  q  h   1 3           g   hue2rgb p  q  h           b   hue2rgb p  q  h - 1 3              return  Math round r   255   Math round g   255   Math round b   255        RGB to HSL          Converts an RGB color value to HSL  Conversion formula    adapted from http   en wikipedia org wiki HSL color space     Assumes r  g  and b are contained in the set  0  255  and    returns h  s  and l in the set  0  1          param    number   r       The red color value     param    number   g       The green color value     param    number   b       The blue color value     return   Array            The HSL representation     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  gt  0 5   d    2 - max - min    d    max   min           switch max               case r  h    g - b    d    g  lt  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

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For when you need RGB to HSV and vice versa instead   function rgbToHsv r  g  b        r    255  g    255  b    255       var min   Math min r  g  b       max   Math max r  g  b       delta   max - min      h   0  s   0  v   max       if  min    max                s    delta   max            switch  max                        case r  h    g - b    delta    g  lt  b   6   0   break              case g  h    b - r    delta   2  break              case b  h    r - g    delta   4  break                     h    6             return  h  s  v      function hsvToRgb h  s  v        var step   h    1   6       pos   step - Math floor step      the hue position within the current step     m    Math floor step    2     1 - pos    v   pos   v     mix color value adjusted to the brightness v      max   1   v      min    1 - s    v      med   m     1 - s     v - m        r  g  b       switch  Math floor step                 case 0              r   max              g   med              b   min              break          case 1              r   med              g   max              b   min              break          case 2              r   min              g   max              b   med              break          case 3              r   min              g   med              b   max              break          case 4              r   med              g   min              b   max              break          case 5              r   max              g   min              b   med              break             return  Math round r   255   Math round g   255   Math round b   255

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With H  S and L in  0 1  range   ConvertHslToRgb  function  iHsl        var min  sv  sextant  fract  vsf       var v    iHsl l  lt   0 5     iHsl l    1   iHsl s      iHsl l   iHsl s - iHsl l   iHsl s       if  v     0          return   Red  0  Green  0  Blue  0         min   2   iHsl l - v      sv    v - min    v      var h    6   iHsl h    6      sextant   Math floor h       fract   h - sextant      vsf   v   sv   fract       switch  sextant                case 0  return   r  v  g  min   vsf  b  min            case 1  return   r  v - vsf  g  v  b  min            case 2  return   r  min  g  v  b  min   vsf            case 3  return   r  min  g  v - vsf  b  v            case 4  return   r  min   vsf  g  min  b  v            case 5  return   r  v  g  min  b  v - vsf

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PHP - shortest but precise Here I rewrite my JS answer  math details are there  to PHP - you can run it here function hsl2rgb  h  s  l        a    s   min  l  1- l      k   function  n  h    return   n  h 30  12       f   function  n  use   h  s  l  a  k           return  l -  a   max  min  k  n  h -3  9- k  n  h   1  -1          return    f 0    f 8    f 4

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Found the easiest way  python to the rescue  D     colorsys hls to rgb h  l  s       Convert the color from HLS coordinates to RGB coordinates

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If you re looking for something that definitely conforms with the CSS semantics for HSL and RGB  you could use the algorithm specified in the CSS 3 specification  which reads   HOW TO RETURN hsl to rgb h  s  l       SELECT         l lt  0 5  PUT l  s 1  IN m2       ELSE  PUT l s-l s IN m2    PUT l 2-m2 IN m1    PUT hue to rgb m1  m2  h 1 3  IN r    PUT hue to rgb m1  m2  h      IN g    PUT hue to rgb m1  m2  h-1 3  IN b    RETURN  r  g  b   HOW TO RETURN hue to rgb m1  m2  h       IF h lt 0  PUT h 1 IN h    IF h gt 1  PUT h-1 IN h    IF h 6 lt 1  RETURN m1  m2-m1  h 6    IF h 2 lt 1  RETURN m2    IF h 3 lt 2  RETURN m1  m2-m1   2 3-h  6    RETURN m1   I believe this is the source for some of the other answers here

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Unity3D C  Code from Mohsen s answer   Here is the code from Mohsen s answer in C  targeted specifically for Unity3D   It was adapted from the C  answer given by Alec Thilenius above   using UnityEngine  using System Collections   public class ColorTools             lt summary gt          Converts an HSL color value to RGB          Input  Vector4   X   0 0  1 0   Y   0 0  1 0   Z   0 0  1 0   W   0 0  1 0     strong text           Output  Color   R   0 0  1 0   G   0 0  1 0   B   0 0  1 0   A   0 0  1 0             lt  summary gt           lt param name  hsl  gt Vector4 defining X   h  Y   s  Z   l  W   a  Ranges  0  1 0  lt  param gt           lt returns gt RGBA Color  Ranges  0 0  1 0  lt  returns gt      public static Color HslToRgba Vector4 hsl                float r  g  b           if  hsl y    0 0f              r   g   b   hsl z          else                       var q   hsl z  lt  0 5f   hsl z    1 0f   hsl y    hsl z   hsl y - hsl z   hsl y              var p   2 0f   hsl z - q              r   HueToRgb p  q  hsl x   1 0f   3 0f               g   HueToRgb p  q  hsl x               b   HueToRgb p  q  hsl x - 1 0f   3 0f                      return new Color r  g  b  hsl w                 Helper for HslToRgba     private static float HueToRgb float p  float q  float t                if  t  lt  0 0f  t    1 0f          if  t  gt  1 0f  t -  1 0f          if  t  lt  1 0f   6 0f  return p    q - p    6 0f   t          if  t  lt  1 0f   2 0f  return q          if  t  lt  2 0f   3 0f  return p    q - p     2 0f   3 0f - t    6 0f          return p                  lt summary gt          Converts an RGB color value to HSL          Input  Color   R   0 0  1 0   G   0 0  1 0   B   0 0  1 0   A   0 0  1 0            Output  Vector4   X   0 0  1 0   Y   0 0  1 0   Z   0 0  1 0   W   0 0  1 0             lt  summary gt           lt param name  rgba  gt  lt  param gt           lt returns gt  lt  returns gt      public static Vector4 RgbaToHsl Color rgba                 float max    rgba r  gt  rgba g  amp  amp  rgba r  gt  rgba b    rgba r                 rgba g  gt  rgba b    rgba g   rgba b          float min    rgba r  lt  rgba g  amp  amp  rgba r  lt  rgba b    rgba r                 rgba g  lt  rgba b    rgba g   rgba b           float h  s  l          h   s   l    max   min    2 0f           if  max    min              h   s   0 0f          else                       float d   max - min              s    l  gt  0 5f    d    2 0f - max - min    d    max   min                if  rgba r  gt  rgba g  amp  amp  rgba r  gt  rgba b                  h    rgba g - rgba b    d    rgba g  lt  rgba b   6 0f   0 0f                else if  rgba g  gt  rgba b                  h    rgba b - rgba r    d   2 0f               else                 h    rgba r - rgba g    d   4 0f               h    6 0f                     return new Vector4 h  s  l  rgba a

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Here is the modified javascript function  it outputs Hue in set 0-360 degrees     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  gt  0 5   d    2 - max - min    d    max   min             switch max                 case r  h    g - b    d   break                case g  h   2      b - r    d   break                case b  h   4      r - g    d   break                        h  60            if  h  lt  0  h   360               return  h  s  l          alert rgbToHsl 125 115 145

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C  Code from Mohsen s answer   Here is the code from Mohsen s answer in C  if anyone else wants it  Note  Color is a custom class and Vector4 is from OpenTK  Both are easy to replace with something else of your choosing   Hsl To Rgba         lt summary gt      Converts an HSL color value to RGB      Input  Vector4   X   0 0  1 0   Y   0 0  1 0   Z   0 0  1 0   W   0 0  1 0        Output  Color   R   0  255   G   0  255   B   0  255   A   0  255         lt  summary gt       lt param name  hsl  gt Vector4 defining X   h  Y   s  Z   l  W   a  Ranges  0  1 0  lt  param gt       lt returns gt RGBA Color  Ranges  0  255  lt  returns gt  public static Color HslToRgba Vector4 hsl        float r  g  b       if  hsl Y    0 0f          r   g   b   hsl Z       else               var q   hsl Z  lt  0 5f   hsl Z    1 0f   hsl Y    hsl Z   hsl Y - hsl Z   hsl Y          var p   2 0f   hsl Z - q          r   HueToRgb p  q  hsl X   1 0f   3 0f           g   HueToRgb p  q  hsl X           b   HueToRgb p  q  hsl X - 1 0f   3 0f              return new Color  int  r   255    int  g   255    int  b   255    int  hsl W   255          Helper for HslToRgba private static float HueToRgb float p  float q  float t        if  t  lt  0 0f  t    1 0f      if  t  gt  1 0f  t -  1 0f      if  t  lt  1 0f   6 0f  return p    q - p    6 0f   t      if  t  lt  1 0f   2 0f  return q      if  t  lt  2 0f   3 0f  return p    q - p     2 0f   3 0f - t    6 0f      return p      Rgba To Hsl         lt summary gt      Converts an RGB color value to HSL      Input  Color   R   0  255   G   0  255   B   0  255   A   0  255        Output  Vector4   X   0 0  1 0   Y   0 0  1 0   Z   0 0  1 0   W   0 0  1 0         lt  summary gt       lt param name  rgba  gt  lt  param gt       lt returns gt  lt  returns gt  public static Vector4 RgbaToHsl Color rgba        float r   rgba R   255 0f      float g   rgba G   255 0f      float b   rgba B   255 0f       float max    r  gt  g  amp  amp  r  gt  b    r    g  gt  b    g   b      float min    r  lt  g  amp  amp  r  lt  b    r    g  lt  b    g   b       float h  s  l      h   s   l    max   min    2 0f       if  max    min          h   s   0 0f       else               float d   max - min          s    l  gt  0 5f    d    2 0f - max - min    d    max   min            if  r  gt  g  amp  amp  r  gt  b              h    g - b    d    g  lt  b   6 0f   0 0f            else if  g  gt  b              h    b - r    d   2 0f           else             h    r - g    d   4 0f           h    6 0f             return new Vector4 h  s  l  rgba A   255 0f

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An hsl a color value  set in javascript  will be instantly converted to rgb a  All you need to do then is access the computed style value  document body style color    hsla 44  100   50   0 8     console log window getComputedStyle document body  color       displays  rgba 255  187  0  0 8    Technically  I guess  this isn t even any lines of code - it s just done automatically   So  depending on your environment  you might be able to get away with just this   Not that there aren t a lot of very thoughtful responses here   I don t know what your goal is   Now  what if you want to convert from rbg a to hsl a

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PHP implementation of  Mohsen s code   including Test   Sorry to re-post this  But I really haven t seen any other implementation that gives the quality I needed         Converts an HSL color value to RGB  Conversion formula    adapted from http   en wikipedia org wiki HSL color space     Assumes h  s  and l are contained in the set  0  1  and    returns r  g  and b in the set  0  255          param    number   h       The hue     param    number   s       The saturation     param    number   l       The lightness     return   Array            The RGB representation        function hue2rgb  p   q   t               if  t  lt  0   t    1              if  t  gt  1   t -  1              if  t  lt  1 6  return  p     q -  p    6    t              if  t  lt  1 2  return  q              if  t  lt  2 3  return  p     q -  p     2 3 -  t    6              return  p            function hslToRgb  h   s   l       if  s    0            r    l           g    l           b    l     achromatic      else           q    l  lt  0 5    l    1    s     l    s -  l    s           p   2    l -  q           r   hue2rgb  p   q   h   1 3            g   hue2rgb  p   q   h            b   hue2rgb  p   q   h - 1 3              return array round  r   255   round  g   255   round  b   255          Uncomment to test     for   i 0  i lt 360  i         rgb hslToRgb  i 360  1   9     echo   lt div style  quot background-color rgb     rgb 0            rgb 1            rgb 2       padding 2px  quot  gt  lt  div gt         End Test

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Shortest but precise - JS Use this JS code  more  rgb2hsl  hsv2rgb rgb2hsv and hsl2hsv  - php here    input  h in  0 360  and s v in  0 1  - output  r g b in  0 1  function hsl2rgb h s l       let a s Math min l 1-l     let f   n k  n h 30  12    gt  l - a Math max Math min k-3 9-k 1  -1                      return  f 0  f 8  f 4           x000D   x000D     oneliner version let hsl2rgb    h s l  a s Math min l 1-l   f   n k  n h 30  12    gt  l - a Math max Math min k-3 9-k 1  -1     gt   f 0  f 8  f 4        r g b are in  0-1   result e g   0812fa  let rgb2hex    r g b    gt         r g b  map x  gt Math round x 255  toString 16  padStart 2 0    join        console log  hsl   30 0 2 0 3  -- gt  rgb     hsl2rgb 30 0 2 0 3    -- gt  hex    rgb2hex    hsl2rgb 30 0 2 0 3             ---------------    UX    ---------------  rgb   0 0 0   hs   0 0 0    let     x   gt  document querySelector x    function changeRGB i e      rgb i  e target value 255    hs   rgb2hsl    rgb     refresh       function changeHS i e      hs i  e target value  i 255 1     rgb  hsl2rgb    hs     refresh       function refresh       rr   rgb map x  gt x 255 0  join         hh   rgb2hex    rgb     tr    RGB    rr     th    HSL    hs map  x i   gt i   x 100  toFixed 2      x 0  join           thh   HEX    hh         box   style backgroundColor  rgb   rr             infoRGB   innerHTML    tr            infoHS   innerHTML     th  n  thh               r   value rgb 0  255        g   value rgb 1  255        b   value rgb 2  255           h   value hs 0         s   value hs 1  255        l   value hs 2  255       function rgb2hsl r g b      let a Math max r g b   n a-Math min r g b   f  1-Math abs a a-n-1       let h  n  amp  amp    a  r     g-b  n     a  g    2  b-r  n   4  r-g  n       return  60  h lt 0 h 6 h   f   n f   0   a a-n  2      refresh    x000D   box     width  50px    height  50px    margin  20px     body       display  flex    x000D   lt div gt   lt input id  r  type  range  min  0  max  255  oninput  changeRGB 0 event   gt R lt br gt   lt input id  g  type  range  min  0  max  255  oninput  changeRGB 1 event   gt G lt br gt   lt input id  b  type  range  min  0  max  255  oninput  changeRGB 2 event   gt B lt br gt   lt pre class  infoRGB  gt  lt  pre gt   lt  div gt     lt div gt   lt div class  box hsl  gt  lt  div gt    lt  div gt    lt div gt   lt input id  h  type  range  min  0  max  360  oninput  changeHS 0 event   gt H lt br gt   lt input id  s  type  range  min  0  max  255  oninput  changeHS 1 event   gt S lt br gt   lt input id  l  type  range  min  0  max  255  oninput  changeHS 2 event   gt L lt br gt   lt pre class  infoHS  gt  lt  pre gt  lt br gt   lt  div gt  x000D   x000D   x000D   Here is formula which I discover and precisely describe in wiki   error analysis

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Php Implementation of Chris s C  Code  Also from here  which explains the math of it very well   This is basically a bunch of functions to convert to and from HSL  Hue Saturation Lightness   Tested and working on PHP 5 6 15  TL DR  The full code can be found here on Pastebin     Hex to HSL  Input  Hex color in format     0f4 or    00ff44  pound sign optional  Output  HSL in Degrees  Percent  Percent         Input  hex color    Output  hsl in ranges from 0-1         Takes the hex  converts it to RGB  and sends    it to RGBToHsl   Returns the output         function hexToHsl  hex         r            g            b             hex   str replace           hex        if  strlen  hex     3             r   substr  hex  0  1            r    r    r           g   substr  hex  1  1            g    g    g           b   substr  hex  2  1            b    b    b        elseif  strlen  hex     6             r   substr  hex  0  2            g   substr  hex  2  2            b   substr  hex  4  2         else           return false              r   hexdec  r        g   hexdec  g        b   hexdec  b         hsl    rgbToHsl  r  g  b       return  hsl      RGB to HSL  Input  RGB in range 0-255 Output  HSL in Degrees  Percent  Percent             Credits     https   stackoverflow com questions 4793729 rgb-to-hsl-and-back-calculation-problems    http   www niwa nu 2013 05 math-behind-colorspace-conversions-rgb-hsl        Called by hexToHsl by default        Converts an RGB color value to HSL  Conversion formula    adapted from http   www niwa nu 2013 05 math-behind-colorspace-conversions-rgb-hsl      Assumes r  g  and b are contained in the range  0 - 255  and    returns h  s  and l in the format Degrees  Percent  Percent         param   Number  r       The red color value     param   Number  g       The green color value     param   Number  b       The blue color value     return  Array           The HSL representation    function rgbToHsl  r   g   b           For the calculation  rgb needs to be in the range from 0 to 1  To convert  divide by 255  ff         r    255       g    255       b    255        myMax   max  r   g   b        myMin   min  r   g   b         maxAdd     myMax    myMin        maxSub     myMax -  myMin          luminence is  max   min  2      h   0       s   0       l     maxAdd   2 0          if all the numbers are equal  there is no saturation  greyscale       if  myMin     myMax           if   l  lt  0 5                 s     maxSub    maxAdd             else                s    2 0 -  myMax -  myMin     note order of opperations - can t use  maxSub here              s     maxSub    s                        find hue         switch  myMax               case  r                    h     g -  b                    h     h    maxSub                   break              case  g                    h     b -  r                     h     h    maxSub                    h     h   2 0                   break              case  b                    h     r -  g                    h     h    maxSub                     h     h   4 0                   break                         hsl   hslToDegPercPerc  h   s   l       return  hsl      HSL  0-1 range  to Degrees  Percent  Percent format  For the math calculations  HSL is easier to deal with in the 0-1 range  but for human readability  it s easier in Degrees  Percent  Percent   This function takes HSL in the ranges 0-1  and returns HSL in Degrees  Percent  Percent          Input  HSL in ranges 0-1     Output  HSL in format Deg  Perc  Perc         Note  rgbToHsl calls this function by default         Multiplies  h by 60  and  s and  l by 100      function hslToDegPercPerc  h   s   l          convert h to degrees      h    60       if   h  lt  0             h    360               convert s and l to percentage      s    100       l    100        hsl  h      h       hsl  s      s       hsl  l      l      return  hsl      HSL  Degrees  Percent  Percent format  to HSL in range 0-1  This function converts HSL in the format Degrees  Percent  Percent  to the ranges 0-1 for easier computing          Input  HSL in format Deg  Perc  Perc    Output  An array containing HSL in ranges 0-1        Divides  h by 60  and  s and  l by 100         hslToRgb calls this by default     function degPercPercToHsl  h   s   l           convert h  s  and l back to the 0-1 range        convert the hue s 360 degrees in a circle to 1      h    360         convert the saturation and lightness to the 0-1        range by multiplying by 100      s    100       l    100        hsl  h       h       hsl  s      s       hsl  l      l       return  hsl      HSL to RGB  Input  HSL in the format Degrees  Percent  Percent Output  RGB in the format 255  255  255          Converts an HSL color value to RGB  Conversion formula    adapted from http   www niwa nu 2013 05 math-behind-colorspace-conversions-rgb-hsl      Assumes h  s  and l are in the format Degrees     Percent  Percent  and returns r  g  and b in     the range  0 - 255         Called by hslToHex by default        Calls        degPercPercToHsl      hueToRgb        param   Number  h       The hue value     param   Number  s       The saturation level     param   Number  l       The luminence     return  Array           The RGB representation     function hslToRgb  h   s   l        hsl   degPercPercToHsl  h   s   l        h    hsl  h         s    hsl  s         l    hsl  l           If there s no saturation  the color is a greyscale        so all three RGB values can be set to the lightness         Hue doesn t matter  because it s grey  not color      if   s    0             r    l   255           g    l   255           b    l   255            else             calculate some temperary variables to make the            calculation eaisier          if   l  lt  0 5                 temp2    l    1    s             else                temp2     l    s  -   s    l                      temp1   2    l -  temp2             run the calculated vars through hueToRgb to           calculate the RGB value   Note that for the Red           value  we add a third  120 degrees   to adjust            the hue to the correct section of the circle for           red   Simalarly  for blue  we subtract 1 3           r   255   hueToRgb  temp1   temp2   h    1   3             g   255   hueToRgb  temp1   temp2   h            b   255   hueToRgb  temp1   temp2   h -  1   3                rgb  r      r       rgb  g      g       rgb  b      b       return  rgb      Hue to RGB  This function is called by hslToRgb to convert the hue into the separate RGB values          Converts an HSL hue to it s RGB value          Input   temp1 and  temp2 - temperary vars based on     whether the lumanence is less than 0 5  and     calculated using the saturation and luminence    values       hue - the hue  to be converted to an RGB     value   For red  add 1 3 to the hue  green     leave it alone  and blue you subtract 1 3     from the hue        Output  One RGB value        Thanks to Easy RGB for this function  Hue 2 RGB      http   www easyrgb com index php X MATH amp  h 19 text19       function hueToRgb  temp1   temp2   hue        if   hue  lt  0              hue    1            if   hue  gt  1             hue -  1             if   6    hue   lt  1             return   temp1     temp2 -  temp1    6    hue         elseif   2    hue   lt  1             return  temp2        elseif   3    hue   lt  2             return   temp1     temp2 -  temp1      2   3  -  hue    6             return  temp1      HSL to Hex  Input  HSL in format Degrees  Percent  Percent Output  Hex in format 00ff22  no pound sign    Converts to RGB  then converts separately to hex          Converts HSL to Hex by converting it to     RGB  then converting that to hex         string hslToHex  h   s   l    prependPound   true          h is the Degrees value of the Hue     s is the Percentage value of the Saturation     l is the Percentage value of the Lightness     prependPound is a bool  whether you want a pound      sign prepended   optional - default true        Calls        hslToRgb       Output  Hex in the format   00ff88  with     pound sign    Rounded to the nearest whole    number     function hslToHex  h   s   l   prependPound   true          convert hsl to rgb      rgb   hslToRgb  h  s  l          convert rgb to hex      hexR    rgb  r         hexG    rgb  g         hexB    rgb  b           round to the nearest whole number      hexR   round  hexR        hexG   round  hexG        hexB   round  hexB          convert to hex      hexR   dechex  hexR        hexG   dechex  hexG        hexB   dechex  hexB          check for a non-two string length       if it s 1  we can just prepend a       0  but if it is anything else non-2        it must return false  as we don t        know what format it is in      if  strlen  hexR     2            if  strlen  hexR     1                  probably in format  0f4  etc               hexR    0     hexR            else                 unknown format             return false                      if  strlen  hexG     2            if  strlen  hexG     1                 hexG    0     hexG            else               return false                      if  strlen  hexB     2            if  strlen  hexB     1                 hexB    0     hexB            else               return false                         if prependPound is set  will prepend a         sign to the beginning of the hex code         default   true       hex           if   prependPound             hex                    hex    hex    hexR    hexG    hexB       return  hex

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C   implementation with probably better performance than  Mohsen code  It uses a  0-6  range for the hue  avoiding the division and multiplication by 6  S and L range is  0 1   void fromRGBtoHSL float rgb    float hsl           const float maxRGB   max rgb 0   max rgb 1   rgb 2          const float minRGB   min rgb 0   min rgb 1   rgb 2          const float delta2   maxRGB   minRGB       hsl 2    delta2   0 5f        const float delta   maxRGB - minRGB       if  delta  lt  FLT MIN           hsl 0    hsl 1    0 0f       else                 hsl 1    delta    hsl 2   gt  0 5f   2 0f - delta2   delta2            if  rgb 0   gt   maxRGB                          hsl 0     rgb 1  - rgb 2     delta               if  hsl 0   lt  0 0f                   hsl 0     6 0f                      else if  rgb 1   gt   maxRGB               hsl 0    2 0f    rgb 2  - rgb 0     delta           else              hsl 0    4 0f    rgb 0  - rgb 1     delta            void fromHSLtoRGB const float hsl    float rgb          if hsl 1   lt  FLT MIN          rgb 0    rgb 1    rgb 2    hsl 2       else if hsl 2   lt  FLT MIN          rgb 0    rgb 1    rgb 2    0 0f      else               const float q   hsl 2   lt  0 5f   hsl 2     1 0f   hsl 1     hsl 2    hsl 1  - hsl 2    hsl 1           const float p   2 0f   hsl 2  - q          float t      hsl 0    2 0f  hsl 0   hsl 0  - 2 0f            for int i 0  i lt 3    i                        if t i   lt  0 0f                  t i     6 0f              else if t i   gt  6 0f                  t i  -  6 0f               if t i   lt  1 0f                  rgb i    p    q - p    t i               else if t i   lt  3 0f                  rgb i    q              else if t i   lt  4 0f                  rgb i    p    q - p     4 0f - t i                else                 rgb i    p

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I needed a really light weight one  Its not 100   but it gets close enough for some usecases                          float3 Hue float h  float s  float l        float r   max cos h   2   UNITY PI    0 5   0 5  0       float g   max cos  h   0 666666    2   UNITY PI    0 5   0 5  0       float b   max cos  h   0 333333    2   UNITY PI    0 5   0 5  0       float gray   0 2989   r   0 5870   g   0 1140   b      return lerp gray  float3 r  g  b   s    smoothstep 0  0 5  l    1   smoothstep 0 5  1  l

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The article for HSL and HSV on wikipedia contains some formulas  The calculations are a bit tricky  so it might be useful to take a look at existing implementations

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I got this from Brandon Mathis  HSL Picker source code   It was originally written in CoffeeScript  I converted it to JavaScript using an online converter  and took out the mechanism to verify the user input was a valid RGB value  This answer worked for my usecase  as the most up-voted answer on this post I found to not produce a valid HSL value   Note that it returns an hsla value  with a representing opacity transparency  0 is completely transparent  and 1 fully opaque    function rgbToHsl rgb      var a  add  b  diff  g  h  hue  l  lum  max  min  r  s  sat    r   parseFloat rgb 0     255    g   parseFloat rgb 1     255    b   parseFloat rgb 2     255    max   Math max r  g  b     min   Math min r  g  b     diff   max - min    add   max   min    hue   min     max   0   r     max     60    g - b    diff    360    360   g     max    60    b - r    diff    120    60    r - g    diff    240    lum   0 5   add    sat   lum     0   0   lum     1   1   lum  lt   0 5   diff   add   diff    2 - add     h   Math round hue     s   Math round sat   100     l   Math round lum   100     a   parseFloat rgb 3      1    return  h  s  l  a

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This is how I do it which is easy to remember is to think of RGB as three spokes on a wheel  120 degrees apart    H   hue  0-360  S   saturation  0-1  L   luminance  0-1   R1   SIN  H     L  G1   SIN  H   120     L  B1   SIN  H   240     L    The tricky part is saturation  which is to a scale down to the average of those three    AVERAGE    R1   G1   B1    3   R2     R1 - AVERAGE    S    AVERAGE  G2     G1 - AVERAGE    S    AVERAGE  B2     B1 - AVERAGE    S    AVERAGE   RED   R2   255  GREEN   G2   255  BLUE   B2   255

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For all who said that Garry Tan solution converting incorrect from RGB to HSL and back  It because he left out fraction part of number in his code  I corrected his code  javascript   Sorry for link on russian languadge  but on english absent - HSL-wiki  function toHsl r  g  b        r    255 0      g    255 0      b    255 0      var max   Math max r  g  b       var min   Math min r  g  b       var h  s  l    max   min    2 0       if max    min                h   s   0             else               var d   max - min          s    l  gt  0 5   d    2 0 - max - min    d    max   min             if max    r  amp  amp  g  gt   b                        h   1 0472    g - b    d                     else if max    r  amp  amp  g  lt  b                        h   1 0472    g - b    d   6 2832                    else if max    g                        h   1 0472    b - r    d   2 0944                    else if max    b                        h   1 0472    r - g    d   4 1888                      return           str   hsl     parseInt h   6 2832   360 0   0 5          parseInt s   100 0   0 5           parseInt l   100 0   0 5                  obj    h  parseInt h   6 2832   360 0   0 5   s  parseInt s   100 0   0 5   l  parseInt l   100 0   0 5

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Java implementation of Mohsen s code  Note that all integer are declared as float  i e 1f  and must be float  else you will optain grey colors   HSL to RGB          Converts an HSL color value to RGB  Conversion formula    adapted from http   en wikipedia org wiki HSL color space     Assumes h  s  and l are contained in the set  0  1  and    returns r  g  and b in the set  0  255          param h       The hue     param s       The saturation     param l       The lightness     return int array  the RGB representation     public static int   hslToRgb float h  float s  float l       float r  g  b       if  s    0f            r   g   b   l     achromatic       else           float q   l  lt  0 5f   l    1   s    l   s - l   s          float p   2   l - q          r   hueToRgb p  q  h   1f 3f           g   hueToRgb p  q  h           b   hueToRgb p  q  h - 1f 3f             int   rgb    to255 r   to255 g   to255 b        return rgb    public static int to255 float v    return  int Math min 255 256 v          Helper method that converts hue to rgb    public static float hueToRgb float p  float q  float t        if  t  lt  0f          t    1f      if  t  gt  1f          t -  1f      if  t  lt  1f 6f          return p    q - p    6f   t      if  t  lt  1f 2f          return q      if  t  lt  2f 3f          return p    q - p     2f 3f - t    6f      return p      RGB to HSL         Converts an RGB color value to HSL  Conversion formula    adapted from http   en wikipedia org wiki HSL color space     Assumes pR  pG  and bpBare contained in the set  0  255  and    returns h  s  and l in the set  0  1          param pR       The red color value     param pG       The green color value     param pB       The blue color value     return float array  the HSL representation     public static float   rgbToHsl int pR  int pG  int pB        float r   pR   255f      float g   pG   255f      float b   pB   255f       float max    r  gt  g  amp  amp  r  gt  b    r    g  gt  b    g   b      float min    r  lt  g  amp  amp  r  lt  b    r    g  lt  b    g   b       float h  s  l      l    max   min    2 0f       if  max    min            h   s   0 0f        else           float d   max - min          s    l  gt  0 5f    d    2 0f - max - min    d    max   min            if  r  gt  g  amp  amp  r  gt  b              h    g - b    d    g  lt  b   6 0f   0 0f            else if  g  gt  b              h    b - r    d   2 0f           else             h    r - g    d   4 0f           h    6 0f             float   hsl    h  s  l       return hsl

[algorithm] HSL to RGB color conversion

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