Class Luminance

  • public class Luminance
extends Object
    The class Luminance is a library of static methods related to the monochrome luminance of a color. It supports computing the monochrome luminance of a color (r, g, b) using the NTSC formula Y = 0.299*r + 0.587*g + 0.114*b; converting the color to a grayscale color, and checking whether two colors are compatible.

    For additional documentation, see Section 3.1 of Computer Science: An Interdisciplinary Approach by Robert Sedgewick and Kevin Wayne.

    Author:
    Robert Sedgewick, Kevin Wayne

    • Constructor Summary

      Constructors 
      Constructor Description
      Luminance()  

    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      static boolean areCompatible​(Color a, Color b)
      Are the two given colors compatible? Two colors are compatible if the difference in their monochrome luminances is at least 128.0).
      static double intensity​(Color color)
      Returns the monochrome luminance of the given color as an intensity between 0.0 and 255.0 using the NTSC formula Y = 0.299*r + 0.587*g + 0.114*b.
      static void main​(String[] args)
      Takes six command-line arguments r1, g1, b1, r2, g2, and b2, prints to standard output the monochrome luminances of (r1, g1, b1) and (r2, g2, b2) and whether they are compatible.
      static Color toGray​(Color color)
      Returns a grayscale version of the given color as a Color object.

    • Constructor Detail

      • Luminance

        public Luminance()

    • Method Detail

      • intensity

        public static double intensity​(Color color)
        Returns the monochrome luminance of the given color as an intensity between 0.0 and 255.0 using the NTSC formula Y = 0.299*r + 0.587*g + 0.114*b. If the given color is a shade of gray (r = g = b), this method is guaranteed to return the exact grayscale value (an integer with no floating-point roundoff error).
        Parameters:
        color - the color to convert
        Returns:
        the monochrome luminance (between 0.0 and 255.0)

      • toGray

        public static Color toGray​(Color color)
        Returns a grayscale version of the given color as a Color object.
        Parameters:
        color - the Color object to convert to grayscale
        Returns:
        a grayscale version of color

      • areCompatible

        public static boolean areCompatible​(Color a,
                                    Color b)
        Are the two given colors compatible? Two colors are compatible if the difference in their monochrome luminances is at least 128.0).
        Parameters:
        a - one color
        b - the other color
        Returns:
        true if colors a and b are compatible; false otherwise

      • main

        public static void main​(String[] args)
        Takes six command-line arguments r1, g1, b1, r2, g2, and b2, prints to standard output the monochrome luminances of (r1, g1, b1) and (r2, g2, b2) and whether they are compatible.
        Parameters:
        args - the six command-line arguments