Package org.pushingpixels.ephemeral.chroma.hct

Class HctSolver

  • public class HctSolver
extends java.lang.Object
    A class that solves the HCT equation.

    • Constructor Summary

      Constructors 
      Modifier Constructor Description
      private HctSolver()  

    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      (package private) static boolean areInCyclicOrder​(double a, double b, double c)  
      (package private) static double[] bisectToLimit​(double y, double targetHue)
      Finds a color with the given Y and hue on the boundary of the cube.
      (package private) static double[][] bisectToSegment​(double y, double targetHue)
      Finds the segment containing the desired color.
      (package private) static double chromaticAdaptation​(double component)  
      (package private) static int criticalPlaneAbove​(double x)  
      (package private) static int criticalPlaneBelow​(double x)  
      (package private) static int findResultByJ​(double hueRadians, double chroma, double y)
      Finds a color with the given hue, chroma, and Y.
      (package private) static double hueOf​(double[] linrgb)
      Returns the hue of a linear RGB color in CAM16.
      (package private) static double intercept​(double source, double mid, double target)
      Solves the lerp equation.
      (package private) static double inverseChromaticAdaptation​(double adapted)  
      (package private) static boolean isBounded​(double x)  
      (package private) static double[] lerpPoint​(double[] source, double t, double[] target)  
      (package private) static double[] midpoint​(double[] a, double[] b)  
      (package private) static double[] nthVertex​(double y, int n)
      Returns the nth possible vertex of the polygonal intersection.
      (package private) static double sanitizeRadians​(double angle)
      Sanitizes a small enough angle in radians.
      (package private) static double[] setCoordinate​(double[] source, double coordinate, double[] target, int axis)
      Intersects a segment with a plane.
      static Cam16 solveToCam​(double hueDegrees, double chroma, double lstar)
      Finds an sRGB color with the given hue, chroma, and L*, if possible.
      static int solveToInt​(double hueDegrees, double chroma, double lstar)
      Finds an sRGB color with the given hue, chroma, and L*, if possible.
      (package private) static double trueDelinearized​(double rgbComponent)
      Delinearizes an RGB component, returning a floating-point number.

      • Methods inherited from class java.lang.Object

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

    • Field Detail

      • SCALED_DISCOUNT_FROM_LINRGB

        static final double[][] SCALED_DISCOUNT_FROM_LINRGB

      • LINRGB_FROM_SCALED_DISCOUNT

        static final double[][] LINRGB_FROM_SCALED_DISCOUNT

      • Y_FROM_LINRGB

        static final double[] Y_FROM_LINRGB

      • CRITICAL_PLANES

        static final double[] CRITICAL_PLANES

    • Constructor Detail

      • HctSolver

        private HctSolver()

    • Method Detail

      • sanitizeRadians

        static double sanitizeRadians​(double angle)
        Sanitizes a small enough angle in radians.
        Parameters:
        angle - An angle in radians; must not deviate too much from 0.
        Returns:
        A coterminal angle between 0 and 2pi.

      • trueDelinearized

        static double trueDelinearized​(double rgbComponent)
        Delinearizes an RGB component, returning a floating-point number.
        Parameters:
        rgbComponent - 0.0 <= rgb_component <= 100.0, represents linear R/G/B channel
        Returns:
        0.0 <= output <= 255.0, color channel converted to regular RGB space

      • chromaticAdaptation

        static double chromaticAdaptation​(double component)

      • hueOf

        static double hueOf​(double[] linrgb)
        Returns the hue of a linear RGB color in CAM16.
        Parameters:
        linrgb - The linear RGB coordinates of a color.
        Returns:
        The hue of the color in CAM16, in radians.

      • areInCyclicOrder

        static boolean areInCyclicOrder​(double a,
                                double b,
                                double c)

      • intercept

        static double intercept​(double source,
                        double mid,
                        double target)
        Solves the lerp equation.
        Parameters:
        source - The starting number.
        mid - The number in the middle.
        target - The ending number.
        Returns:
        A number t such that lerp(source, target, t) = mid.

      • lerpPoint

        static double[] lerpPoint​(double[] source,
                          double t,
                          double[] target)

      • setCoordinate

        static double[] setCoordinate​(double[] source,
                              double coordinate,
                              double[] target,
                              int axis)
        Intersects a segment with a plane.
        Parameters:
        source - The coordinates of point A.
        coordinate - The R-, G-, or B-coordinate of the plane.
        target - The coordinates of point B.
        axis - The axis the plane is perpendicular with. (0: R, 1: G, 2: B)
        Returns:
        The intersection point of the segment AB with the plane R=coordinate, G=coordinate, or B=coordinate

      • isBounded

        static boolean isBounded​(double x)

      • nthVertex

        static double[] nthVertex​(double y,
                          int n)
        Returns the nth possible vertex of the polygonal intersection.
        Parameters:
        y - The Y value of the plane.
        n - The zero-based index of the point. 0 <= n <= 11.
        Returns:
        The nth possible vertex of the polygonal intersection of the y plane and the RGB cube, in linear RGB coordinates, if it exists. If this possible vertex lies outside of the cube, [-1.0, -1.0, -1.0] is returned.

      • bisectToSegment

        static double[][] bisectToSegment​(double y,
                                  double targetHue)
        Finds the segment containing the desired color.
        Parameters:
        y - The Y value of the color.
        targetHue - The hue of the color.
        Returns:
        A list of two sets of linear RGB coordinates, each corresponding to an endpoint of the segment containing the desired color.

      • midpoint

        static double[] midpoint​(double[] a,
                         double[] b)

      • criticalPlaneBelow

        static int criticalPlaneBelow​(double x)

      • criticalPlaneAbove

        static int criticalPlaneAbove​(double x)

      • bisectToLimit

        static double[] bisectToLimit​(double y,
                              double targetHue)
        Finds a color with the given Y and hue on the boundary of the cube.
        Parameters:
        y - The Y value of the color.
        targetHue - The hue of the color.
        Returns:
        The desired color, in linear RGB coordinates.

      • inverseChromaticAdaptation

        static double inverseChromaticAdaptation​(double adapted)

      • findResultByJ

        static int findResultByJ​(double hueRadians,
                         double chroma,
                         double y)
        Finds a color with the given hue, chroma, and Y.
        Parameters:
        hueRadians - The desired hue in radians.
        chroma - The desired chroma.
        y - The desired Y.
        Returns:
        The desired color as a hexadecimal integer, if found; 0 otherwise.

      • solveToInt

        public static int solveToInt​(double hueDegrees,
                             double chroma,
                             double lstar)
        Finds an sRGB color with the given hue, chroma, and L*, if possible.
        Parameters:
        hueDegrees - The desired hue, in degrees.
        chroma - The desired chroma.
        lstar - The desired L*.
        Returns:
        A hexadecimal representing the sRGB color. The color has sufficiently close hue, chroma, and L* to the desired values, if possible; otherwise, the hue and L* will be sufficiently close, and chroma will be maximized.

      • solveToCam

        public static Cam16 solveToCam​(double hueDegrees,
                               double chroma,
                               double lstar)
        Finds an sRGB color with the given hue, chroma, and L*, if possible.
        Parameters:
        hueDegrees - The desired hue, in degrees.
        chroma - The desired chroma.
        lstar - The desired L*.
        Returns:
        A CAM16 object representing the sRGB color. The color has sufficiently close hue, chroma, and L* to the desired values, if possible; otherwise, the hue and L* will be sufficiently close, and chroma will be maximized.