Class Luminance

Object

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 and Description
Luminance()

Method Summary

Modifier and Type	Method and Description
static boolean	areCompatible(java.awt.Color a, java.awt.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(java.awt.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 double	lum(java.awt.Color color) Deprecated. Replaced by intensity(Color).
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 java.awt.Color	toGray(java.awt.Color color) Returns a grayscale version of the given color as a Color object.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Luminance

public Luminance()

Method Detail

lum

@Deprecated
public static double lum(java.awt.Color color)

Deprecated. Replaced by intensity(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.

Parameters:

color - the color to convert

Returns:

the monochrome luminance (between 0.0 and 255.0)

intensity

public static double intensity(java.awt.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 java.awt.Color toGray(java.awt.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(java.awt.Color a,
                                    java.awt.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