Class HctSolver

java.lang.Object
org.pushingpixels.ephemeral.chroma.hct.HctSolver
public class HctSolver extends Object
A class that solves the HCT equation.

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    (package private) static final double[]
    CRITICAL_PLANES
     
    (package private) static final double[][]
    LINRGB_FROM_SCALED_DISCOUNT
     
    (package private) static final double[][]
    SCALED_DISCOUNT_FROM_LINRGB
     
    (package private) static final double[]
    Y_FROM_LINRGB
     

  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
    private
    HctSolver()
     

  • Method Summary

    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 Object

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

  • Field Details

    • 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 Details

    • HctSolver

      private HctSolver()

  • Method Details

    • 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 invalid input: '<'= rgb_component invalid input: '<'= 100.0, represents linear R/G/B channel
      Returns:
      0.0 invalid input: '<'= output invalid input: '<'= 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 invalid input: '<'= n invalid input: '<'= 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.