Website content accessibility-comparison standards of background and foreground colors

This week I encountered a color contrast test problem at work: that is, the foreground color of the text on the webpage should be compared with the background color of the text Wcag (Web Content Accessibility guide. This document provides some standard requirements for web content, so that your website content can be accessed to the best possible level. There is one ( G18 According to the formula, the color contrast must meet the requirements of at least 4.5: 1, which makes it easier for human eyes to distinguish the background color from the foreground color. Here is my personal C # implementation:

   ///     <Summary>  
  ///  Convert hexadecimal color values to RGB Arrays
  ///     </Summary>  
 ///     <Param name = "hexadecimal">  Color hexadecimal value eg: # ff1a2b  </Param>  
  ///     <Returns>  RGB Array  </Returns>  
    Public     Byte [] Converthex (  String  Hexadecimal)
{
  Byte  [] Resultbyte  =     New     Byte  [  3  ];
  Int  Num  =    0  ;
Hexadecimal  =  Hexadecimal. Trim (  '  #  '  );

  //  It is possible to input an argb value.  
    If  (Hexadecimal. Length  >  6 )
{
Hexadecimal  =  Hexadecimal. Remove (  0  ,  2  );
}

  For  (  Int  I  =     0  ; I  <    6  ; I  ++  )
{
  If  (I  %  2  =  0  )
{
Stringbuilder sb  =     New  Stringbuilder ();
SB. append (hexadecimal [I]);
SB. append (hexadecimal [I +     1  ]);

Resultbyte [num  ++  ]  =  Convert. tobyte (sb. tostring (),  16  );
}
}

  Return  Resultbyte;

}

  ///     <Summary> 
  ///  Compare two-color contrast
  ///     </Summary>  
  ///     <Param name = "rgb1"> </param>  
  ///     <Param name = "rgb2"> </param>  
  ///    <Returns>  Comparison Value  </Returns>  
    Public     Double  Colorcompare (  Byte  [] Rgb1,  Byte  [] Rgb2)
{
  Double  L1  = Relativeluminance (rgb1 );
  Double  L2  =  Relativeluminance (rgb2 );
  Double  Result  =  (Math. Max (L1, L2)  +     0.05  )  /  (Math. Min (L1, L2)  +    0.05  );

  Return  Math. Round (result,  2  );
}

  Private     Double  Relativeluminance (  Byte  [] RGB)
{
  Double  RS  = RGB [  0  ]  *     1.0     /     255  ;
  Double  GS  =  RGB [  1  ]  *    1.0     /     255  ;
  Double  BS  =  RGB [  2  ]  *     1.0     /    255  ;
  Double  R, G, B;

R  =  RS  <=     0.03928     ?  RS  /     12.92  : Math. Pow (RS +     0.055  )  /     1.055  ,  2.4  );
G  =  GS  <=     0.03928     ?  GS /     12.92  : Math. Pow (GS  +     0.055  )  /     1.055  ,  2.4  );
B  =  BS  <=    0.03928     ?  BS  /     12.92  : Math. Pow (BS  +     0.055  )  /     1.055  ,  2.4  );

 Return     0.2126     *  R  +     0.7152     *  G  +     0.0722     *  B;
}