NAME

ICC::Shared - Parent class for ICC::Profile and ICC::Support modules.

SYNOPSIS

    use parent 'ICC::Shared'; # add as parent class (to another module)

    use ICC::Shared; # export all functions and constants

    use ICC::Shared qw(Lab2xyz xyz2Lab D50); # export selected functions and a constant

    # copy an object
    $clone = $obj->copy(); # copy an object
    @clones = $obj->copy(4); # make an array of 4 copies

        # store an object
    $flag = $obj->store($file_path); # store serialized object

    # print object structure
    $obj->dump();
    $obj->dump($format);

    # Math::Matrix additions
    $matrix->sdump([$format]); # print object contents to string
    $matrix->dump([$format]); # print object contents
    $matrix2 = $matrix->power($exponent); # exponentiate matrix elements, exponent may be a scalar or vector
    $matrix2 = $matrix->xyz2XYZ([$XYZ_white_point]); # convert matrix working space from xyz to XYZ
    $matrix2 = $matrix->XYZ2xyz([$XYZ_white_point]); # convert matrix working space from XYZ to xyz

    # color encoding functions
    @Lab = xyz2Lab(@xyz); @xyz = Lab2xyz(@Lab); # array
    $Lab = xyz2Lab($xyz); $xyz = Lab2xyz($Lab); # vector, matrix, array structure

    @Lxyz = xyz2Lxyz(@xyz); @xyz = Lxyz2xyz(@Lxyz); # array
    $Lxyz = xyz2Lxyz($xyz); $xyz = Lxyz2xyz($Lxyz); # vector, matrix, array structure

    @Lab = Lxyz2Lab(@Lxyz); @Lxyz = Lab2Lxyz(@Lab); # array
    $Lab = Lxyz2Lab($Lxyz); $Lxyz = Lab2Lxyz($Lab); # vector, matrix, array structure

    @Lab = XYZ2Lab(@XYZ); @XYZ = Lab2XYZ(@Lab); # array (D50)
    $Lab = XYZ2Lab($XYZ); $XYZ = Lab2XYZ($Lab); # vector, matrix, array structure (D50)
    @Lab = XYZ2Lab(@XYZ, $wtpt); @XYZ = Lab2XYZ(@Lab, $wtpt); # array
    $Lab = XYZ2Lab($XYZ, $wtpt); $XYZ = Lab2XYZ($Lab, $wtpt); # vector, matrix, array structure

    @Lxyz = XYZ2Lxyz(@XYZ); @XYZ = Lxyz2XYZ(@Lxyz); # array (D50)
    $Lxyz = XYZ2Lxyz($XYZ); $XYZ = Lxyz2XYZ($Lxyz); # vector, matrix, array structure (D50)
    @Lxyz = XYZ2Lxyz(@XYZ, $wtpt); @XYZ = Lxyz2XYZ(@Lxyz, $wtpt); # array
    $Lxyz = XYZ2Lxyz($XYZ, $wtpt); $XYZ = Lxyz2XYZ($Lxyz, $wtpt); # vector, matrix, array structure

    @XYZ = xyz2XYZ(@xyz); @xyz = XYZ2xyz(@XYZ); # array (D50)
    $XYZ = xyz2XYZ($xyz); $xyz = XYZ2xyz($XYZ); # vector, matrix, array structure (D50)
    @XYZ = xyz2XYZ(@xyz, $wtpt); @xyz = XYZ2xyz(@XYZ, $wtpt); # array
    $XYZ = xyz2XYZ($xyz, $wtpt); $xyz = XYZ2xyz($XYZ, $wtpt); # vector, matrix, array structure

    @xyY = XYZ2xyY(@XYZ); @XYZ = xyY2XYZ(@xyY); # array
    $xyY = XYZ2xyY($XYZ); $XYZ = xyY2XYZ($xyY); # vector, matrix, array structure

    $L = x2L($x); $x = L2x($L); # CIE L* function

    $dLdx = dLdx($x); $dxdL = dxdL($L); derivative of CIE L* function

    $jac = xyz2Lab_jac($xyz); # Jacobian matrix of xyz2Lab function
    $jac = Lab2xyz_jac($Lab); # Jacobian matrix of Lab2xyz function

    $W = XYZ2W(@XYZ, $wtpt); # CIE Whiteness

    $dwv = xyz2dwv($xyz); # density weighted value

    # color difference functions
    $dE = dEab(@Lab1, @Lab2); # CIE ∆E*ab color difference
    $dE = dE94(@Lab1, @Lab2); # CIE ∆E94 color difference
    $dE = dE00(@Lab1, @Lab2); # CIE ∆E00 color difference
    $dE = dE99(@Lab1, @Lab2); # DIN99 color difference
    $dE = dE99(@Lab1, @Lab2, Ke, Kch); # DIN99 color difference
    $dE = dEcmc(@Lab1, @Lab2); # CMC(l:c) color difference
    $dE = dEcmc(@Lab1, @Lab2, l, c); # CMC(l:c) color difference
    $dF = dCh(@Lab1, @Lab2); # ∆Ch chroma difference

    # illuminant functions
    ($cct, $err) = CCT($x, $y); # correlated color temperature
    $cct = CCT2($x, $y); # correlated color temperature using McCamy's approximation
    $rad = bbrad($nm, $T); # black body radiance using Planck's law
    ($x, $y) = bbxy($T); # chromaticity of black body radiator
    ($u, $v) = bbuv($T); CIE UCS 1960 of black body radiator
    ($u, $v) = XYZ2ucs(@XYZ); # CIE UCS 1960
    ($u, $v) = xy2ucs(@xy); # CIE UCS 1960
    ($range, $spd) = daylight($cct); range and SPD of daylight

    # interpolation functions
    $vec_out = linear($vec_in, $range_in, $range_out); # interpolate a vector (linear)
    $matrix = linear_matrix($range_in, $range_out); # make interpolating matrix (linear)
    $vec_out = cspline($vec_in, $range_in, $range_out); # interpolate a vector (natural cubic spline)
    $matrix = cspline_matrix($range_in, $range_out); # make interpolating matrix (natural cubic spline)
    $vec_out = lagrange($vec_in, $range_in, $range_out); # interpolate a vector (Lagrange, ASTM E 2022)
    $matrix = lagrange_matrix($range_in, $range_out); # make interpolating matrix (Lagrange, ASTM E 2022)

    # vector functions
    $scalar = dotProduct($vec1, $vec2); # vector dot product
    $vector = crossProduct($vec1, $vec2); # vector cross product

    # utility functions
    $vector = flatten($structure); # flatten an array structure
    clip_struct($structure); # clip each element of an array structure
    $integer = round($value); # round off value to nearest integer (+/-)
    $vector = s15f162v($s15f16); # convert from s15Fixed16Number vector
    $s15f16 = v2s15f16($vector); # convert to s15Fixed16Number vector
    (profiles_folder_path, directory_segs, customer, job) = makeProfileFolder(file/folder_path); # make folder for profiles
    (profiles_folder_path, directory_segs, customer, job) = makeProfileFolder(file/folder_path, alias_folder_path);
    $path = getICCPath(); # get path to 'ICC' distribution folder
    $path = getICCPath('Data'); # get path to 'ICC' distribution 'Data' folder
    $path = getICCPath('Data/ASTM_E308_data.yml'); # get path to 'ICC' distribution 'ASTM_E308_data.yml' file
    filterPath($path); # interpret '~' and '\' in file paths
    setFile(path_to_file, creator, type); # set Mac OSX creator and file type (deprecated by Apple)
    $array_ref = parse_tokens($token_string) # splits string into tokens, and parses any parameters
    $flag = is_vector($vec); # test if parameter is a vector (values may be numeric or undef)
    $flag = is_num_vector($vec); # test if parameter is a vector (values must be numeric)
    $flag = is_matrix($mat); # test if parameter is a matrix (values may be numeric or undef)
    $flag = is_num_matrix($mat); # test if parameter is a matrix (values must be numeric)

    # constants
    D50 – D50 illuminant XYZ values (CIE 1931 2 degree observer)
    d50 – D50 illuminant XYZ values, encoded as 32-bit ICC XYZNumber
    d50P – D50 illuminant XYZ values, encoded as 16-bit ICC XYZ
    PI –  circumference of a unit circle, approximately 3.14159
    radian – degrees in a radian, approximately 57.29578
    ln10 –  natural logarithm of 10, approximately 2.30258

DESCRIPTION

ICC::Shared is a parent class for all ICC::Profile and ICC::Support modules. It includes a collection of useful functions and constants.

Data structure and functions

Many functions provided by this module take color data for their input. All of these functions will take an array as input. Some functions will also take vector, matrix and array structure inputs, as noted in the Usage section. Here are examples of the various data structures,

    @list = (50, 20, 20); # single sample, an array, also known as a list

    $vector = [50, 20, 20]; # single sample, a vector

    $matrix = [
        [50, 20, 20],
        [50, 20, 20],
        [50, 20, 20],
    ]; # multiple samples, a matrix, also known as a 2-D array

    $struct = [
        [50, 20, 20],
        [
            [50, 20, 20],
            [50, 20, 20],
        ]
    ]; # multiple samples, an array structure

Functions that take vector, matrix and array structure inputs will return the same data type and structure.

Color spaces

There are many ways to encode colorimetric measurements. These are normally called color spaces.

The basic calculation of colorimetry from spectral measurements produces so-called tristimulus values – the CIE XYZ color space. By convention, the XYZ values of an illuminant are scaled so that the Y-value is 100. A perfectly white reference sample will have the same XYZ values as the illuminant.

When the XYZ values of a sample are divided by the XYZ values of the illuminant, the result is xyz values (lower case), which normally range from 0 - 1 (unless there is fluorescence).

In 1976, the CIE standardized a perceptually uniform color space called CIE L*a*b*. The transformation from xyz to L*a*b* is non-linear. The x, y and z values are passed through an identical non-linear transform. The transformed y value is known as L* or lightness. The a* and b* values are computed from the difference between the transformed y value, and the the transformed x and z values.

The intermediate L*a*b* calculation, where x, y and z are transformed non-linearly, is often useful. This is called Lxyz color space. It is not a CIE standard color space.

The color encoding functions below convert all 12 combinations of these color spaces – XYZ, xyz, L*a*b* and Lxyz. The 6 functions involving XYZ require the illuminant white point. If this is omitted, D50 illuminant is used.

Sometimes XYZ values are converted to chromaticity values, or xyY color space. The x and y values indicate color, and the Y value Lightness. This color space is generally used for illuminants.

METHODS

Common methods

copy

This method copies (clones) an object. The copies are separate objects.

Usage

    $clone = $obj->copy(); # copy an object
    @clones = $obj->copy(4); # make an array of 4 copies

Examples

    use ICC::Profile;

    $curve = ICC::Profile::curv->new([0, 1]); # make a 'curv' object
    $curve_set = ICC::Profile::cvst->new([$curve->copy(4)]); # make a 'cvst' object

store

This method stores an object using the 'Storable::store' function.

Usage

    $flag = $obj->store($file_path); # store serialized object
    $obj = Storable::retrieve($file_path); # retrieve the object

dump

This method prints the structure of an object.

Usage

    $obj->dump();
    $obj->dump($format);

Examples

    use ICC::Profile;

    $profile = ICC::Profile->new('~/Desktop/my_profile.icc'); # make a 'Profile' object
    $profile->dump(); # print the object structure

Math::Matrix additions

A few methods are appended to the standard Math::Matrix module. Rather than subclass a new module, we just put them in the Math::Matrix name space.

sdump

print object contents to string

dump

print object contents

clip

clip matrix elements

power

exponentiate matrix elements

xyz2XYZ, XYZ2xyz

convert matrix working space between xyz and XYZ

FUNCTIONS

Color encoding functions

xyz2Lab, Lab2xyz

These functions convert between xyz and L*a*b* encoding.

Usage

    @Lab = xyz2Lab(@xyz); @xyz = Lab2xyz(@Lab); # array
    $Lab = xyz2Lab($xyz); $xyz = Lab2xyz($Lab); # vector, matrix, array structure

Examples

    use ICC::Profile;

    $chart = ICC::Support::Chart->new(''~/Desktop/GRACoL2006_Coated1_CGATS.txt'); # make a 'Chart' object
    $xyz = $chart->xyz([], {'encoding' => 9}); # get all xyz data

    $Lab = xyz2Lab($xyz); # convert xyz matrix to L*a*b* encoding
    $xyz_rt = Lab2xyz($Lab); # convert back to xyz encoding
    $vector = xyz2Lab($xyz->[0]); # convert a vector
    @array = xyz2Lab(@{$xyz->[0]}); # convert an array

xyz2Lxyz, Lxyz2xyz

These functions convert between xyz and Lxyz encoding.

Usage

    @Lxyz = xyz2Lxyz(@xyz); @xyz = Lxyz2xyz(@Lxyz); # array
    $Lxyz = xyz2Lxyz($xyz); $xyz = Lxyz2xyz($Lxyz); # vector, matrix, array structure

Examples

    use ICC::Profile;

    $chart = ICC::Support::Chart->new(''~/Desktop/GRACoL2006_Coated1_CGATS.txt'); # make a 'Chart' object
    $xyz = $chart->xyz([], {'encoding' => 9}); # get all xyz data

    $Lxyz = xyz2Lxyz($xyz); # convert xyz matrix to Lxyz encoding
    $xyz_rt = Lxyz2xyz($Lxyz); # convert back to xyz encoding
    $vector = xyz2Lxyz($xyz->[0]); # convert a vector
    @array = xyz2Lxyz(@{$xyz->[0]}); # convert an array

Lab2Lxyz, Lxyz2Lab

These functions convert between L*a*b* and Lxyz encoding.

Usage

    @Lxyz = Lab2Lxyz(@Lab); @Lab = Lxyz2Lab(@Lxyz); # array
    $Lxyz = Lab2Lxyz($Lab); $Lab = Lxyz2Lab($Lxyz); # vector, matrix, array structure

Examples

    use ICC::Profile;

    $chart = ICC::Support::Chart->new(''~/Desktop/GRACoL2006_Coated1_CGATS.txt'); # make a 'Chart' object
    $Lab = $chart->Lab([]); # get all L*a*b* data

    $Lxyz = Lab2Lxyz($Lab); # convert L*a*b* matrix to Lxyz encoding
    $Lab_rt = Lxyz2Lab($Lxyz); # convert back to L*a*b* encoding
    $vector = Lab2Lxyz($Lab->[0]); # convert a vector
    @array = Lab2Lxyz(@{$Lab->[0]}); # convert an array

XYZ2Lab, Lab2XYZ

These functions convert between XYZ and L*a*b* encoding.

Usage

    @Lab = XYZ2Lab(@XYZ); @XYZ = Lab2XYZ(@Lab); # array (D50)
    $Lab = XYZ2Lab($XYZ); $XYZ = Lab2XYZ($Lab); # vector, matrix, array structure (D50)
    @Lab = XYZ2Lab(@XYZ, $wtpt); @XYZ = Lab2XYZ(@Lab, $wtpt); # array
    $Lab = XYZ2Lab($XYZ, $wtpt); $XYZ = Lab2XYZ($Lab, $wtpt); # vector, matrix, array structure

Examples

    use ICC::Profile;

    $chart = ICC::Support::Chart->new(''~/Desktop/GRACoL2006_Coated1_CGATS.txt'); # make a 'Chart' object
    $XYZ = $chart->xyz([]); # get all XYZ data

    # illuminant is D50 (default)
    $Lab = XYZ2Lab($XYZ); # convert XYZ matrix to L*a*b* encoding
    $XYZ_rt = Lab2XYZ($Lab); # convert back to XYZ encoding
    $vector = XYZ2Lab($XYZ->[0]); # convert a vector
    @array = XYZ2Lab(@{$XYZ->[0]}); # convert an array

    # get F11 illuminant white point
    $color = ICC::Support::Color->new({'illuminant' => 'F11'});
    $wtpt = $color->iwtpt();

    # illuminant is F11 (see note 1)
    $Lab = XYZ2Lab($XYZ, $wtpt); # convert XYZ matrix to L*a*b* encoding
    $XYZ_rt = Lab2XYZ($Lab, $wtpt); # convert back to XYZ encoding
    $vector = XYZ2Lab($XYZ->[0], $wtpt); # convert a vector
    @array = XYZ2Lab(@{$XYZ->[0]}, $wtpt); # convert an array
  1. These L*a*b* values are computed per CIE 15. Be aware that the PCS for ICC profiles is always D50, and that non-D50 XYZ values are transformed to D50 using a CAT (Chromatic Adaptation Transform) before converting to L*a*b*. See Annex E of the ICC specification for an explanation. A CAT may be created directly using the ICC::Profile::matf module, or as a hash option in ICC::Support::Chart.

XYZ2Lxyz, Lxyz2XYZ

These functions convert between XYZ and Lxyz encoding.

Usage

    @Lxyz = XYZ2Lxyz(@XYZ); @XYZ = Lxyz2XYZ(@Lxyz); # array (D50)
    $Lxyz = XYZ2Lxyz($XYZ); $XYZ = Lxyz2XYZ($Lxyz); # vector, matrix, array structure (D50)
    @Lxyz = XYZ2Lxyz(@XYZ, $wtpt); @XYZ = Lxyz2XYZ(@Lxyz, $wtpt); # array
    $Lxyz = XYZ2Lxyz($XYZ, $wtpt); $XYZ = Lxyz2XYZ($Lxyz, $wtpt); # vector, matrix, array structure

Examples

    use ICC::Profile;

    $chart = ICC::Support::Chart->new(''~/Desktop/GRACoL2006_Coated1_CGATS.txt'); # make a 'Chart' object
    $XYZ = $chart->xyz([]); # get all XYZ data

    # illuminant is D50 (default)
    $Lxyz = XYZ2Lxyz($XYZ); # convert XYZ matrix to Lxyz encoding
    $XYZ_rt = Lxyz2XYZ($Lxyz); # convert back to XYZ encoding
    $vector = XYZ2Lxyz($XYZ->[0]); # convert a vector
    @array = XYZ2Lxyz(@{$XYZ->[0]}); # convert an array

    # get F11 illuminant white point
    $color = ICC::Support::Color->new({'illuminant' => 'F11'});
    $wtpt = $color->iwtpt();

    # illuminant is F11 (see note 1)
    $Lxyz = XYZ2Lxyz($XYZ, $wtpt); # convert XYZ matrix to Lxyz encoding
    $XYZ_rt = Lxyz2XYZ($Lxyz, $wtpt); # convert back to XYZ encoding
    $vector = XYZ2Lxyz($XYZ->[0], $wtpt); # convert a vector
    @array = XYZ2Lxyz(@{$XYZ->[0]}, $wtpt); # convert an array
  1. These Lxyz values are computed per CIE 15. Be aware that the PCS for ICC profiles is always D50, and that non-D50 XYZ values are transformed to D50 using a CAT (Chromatic Adaptation Transform) before converting to Lxyz. See Annex E of the ICC specification for an explanation. A CAT may be created directly using the ICC::Profile::matf module, or as a hash option in ICC::Support::Chart.

XYZ2xyz, xyz2XYZ

These functions convert between XYZ and xyz encoding.

Usage

    @xyz = XYZ2xyz(@XYZ); @XYZ = xyz2XYZ(@xyz); # array (D50)
    $xyz = XYZ2xyz($XYZ); $XYZ = xyz2XYZ($xyz); # vector, matrix, array structure (D50)
    @xyz = XYZ2xyz(@XYZ, $wtpt); @XYZ = xyz2XYZ(@xyz, $wtpt); # array
    $xyz = XYZ2xyz($XYZ, $wtpt); $XYZ = xyz2XYZ($xyz, $wtpt); # vector, matrix, array structure

Examples

    use ICC::Profile;

    $chart = ICC::Support::Chart->new(''~/Desktop/GRACoL2006_Coated1_CGATS.txt'); # make a 'Chart' object
    $XYZ = $chart->xyz([]); # get all XYZ data

    # illuminant is D50 (default)
    $xyz = XYZ2xyz($XYZ); # convert XYZ matrix to xyz encoding
    $XYZ_rt = xyz2XYZ($xyz); # convert back to XYZ encoding
    $vector = XYZ2xyz($XYZ->[0]); # convert a vector
    @array = XYZ2xyz(@{$XYZ->[0]}); # convert an array

    # get F11 illuminant white point
    $color = ICC::Support::Color->new({'illuminant' => 'F11'});
    $wtpt = $color->iwtpt();

    # illuminant is F11 (see note 1)
    $xyz = XYZ2xyz($XYZ, $wtpt); # convert XYZ matrix to xyz encoding
    $XYZ_rt = xyz2XYZ($xyz, $wtpt); # convert back to XYZ encoding
    $vector = XYZ2xyz($XYZ->[0], $wtpt); # convert a vector
    @array = XYZ2xyz(@{$XYZ->[0]}, $wtpt); # convert an array
  1. These xyz values are computed per CIE 15. Be aware that the PCS for ICC profiles is always D50, and that non-D50 XYZ values are transformed to D50 using a CAT (Chromatic Adaptation Transform) before converting to xyz. See Annex E of the ICC specification for an explanation. A CAT may be created directly using the ICC::Profile::matf module, or as a hash option in ICC::Support::Chart.

XYZ2xyY, xyY2XYZ

These functions convert between XYZ and xyY encoding. The x and y values are called chromaticity coordinates, and are often shown on a chromaticity diagram. See https://en.wikipedia.org/wiki/File:CIE1931xy_blank.svg.

Usage

    @xyY = XYZ2xyY(@XYZ); @XYZ = xyY2XYZ(@xyY); # array
    $xyY = XYZ2xyY($XYZ); $XYZ = xyY2XYZ($xyY); # vector, matrix, array structure

Examples

    use ICC::Profile;

    $chart = ICC::Support::Chart->new(''~/Desktop/GRACoL2006_Coated1_CGATS.txt'); # make a 'Chart' object
    $XYZ = $chart->xyz([]); # get all XYZ data

    $xyY = XYZ2xyY($XYZ); # convert XYZ matrix to xyY encoding
    $XYZ_rt = xyY2XYZ($xyY); # convert back to XYZ encoding
    $vector = XYZ2xyY($XYZ->[0]); # convert a vector
    @array = XYZ2xyY(@{$XYZ->[0]}); # convert an array

x2L, L2x

These functions convert between linear and CIE L* encoding.

Usage

    $L = x2L($x); $x = L2x($L); # CIE L* function

Examples

    use ICC::Profile;

    $chart = ICC::Support::Chart->new(''~/Desktop/GRACoL2006_Coated1_CGATS.txt'); # make a 'Chart' object
    $xyz = $chart->xyz([], {'encoding' => 9}); # get all xyz data

    $L = x2L($xyz->[99][1]); # compute L* value of sample 99
    $y = L2x($L); # convert back to y value

dLdx, dxdL

These functions compute the derivatives of the CIE L* function and its inverse.

Usage

    $dLdx = dLdx($x); $dxdL = dxdL($L); derivative of CIE L* function

Examples

xyz2Lab_jac, Lab2xyz_jac

These functions compute the Jacobian matrix of the xyz2Lab and Lab2xyz functions.

Usage

    $jac = xyz2Lab_jac($xyz); # Jacobian matrix of xyz2Lab function
    $jac = Lab2xyz_jac($Lab); # Jacobian matrix of Lab2xyz function

Examples

XYZ2W

This function computes the CIE Whiteness value.

Usage

    $W = XYZ2W(@XYZ, $wtpt); # CIE Whiteness

Examples

xyz2dwv

This function computes the density weighted value.

Usage

    $dwv = xyz2dwv($xyz); # density weighted value

Examples

Color difference functions

dEab

This function computes the CIE ∆E*ab color difference.

Usage

    $dE = dEab(@Lab1, @Lab2); # CIE ∆E*ab color difference

Examples

dE94

This function computes the CIE ∆E94 color difference.

Usage

    $dE = dE94(@Lab1, @Lab2); # CIE ∆E94 color difference

Examples

dE00

This function computes the CIE ∆E00 color difference.

Usage

    $dE = dE00(@Lab1, @Lab2); # CIE ∆E00 color difference

Examples

dE99

This function computes the DIN99 color difference

Usage

    $dE = dE99(@Lab1, @Lab2); # DIN99 color difference
    $dE = dE99(@Lab1, @Lab2, Ke, Kch); # DIN99 color difference

Examples

dEcmc

This function computes the CMC(l:c) color difference.

Usage

    $dE = dEcmc(@Lab1, @Lab2); # CMC(l:c) color difference
    $dE = dEcmc(@Lab1, @Lab2, l, c); # CMC(l:c) color difference

Examples

dCh

This function computes the ∆Ch chroma difference, also known as ∆F.

Usage

    $dF = dCh(@Lab1, @Lab2); # ∆Ch chroma difference

Examples

Illuminant functions

CCT

This function computes the correlated color temperature of an illuminant, and the black body error value.

Usage

    ($cct, $err) = CCT($x, $y); # correlated color temperature

Examples

CCT2

This function computes the correlated color temperature of an illuminant using McCamy's approximation.

Usage

    $cct = CCT2($x, $y); # correlated color temperature using McCamy's approximation

Examples

bbrad

This function computes the black body radiance using Planck's law.

Usage

    $rad = bbrad($nm, $T); # black body radiance using Planck's law

Examples

bbxy

This function computes the chromaticity of black body radiator.

Usage

    ($x, $y) = bbxy($T); # chromaticity of black body radiator

Examples

bbuv

This function computes the CIE UCS 1960 coordinates of black body radiator.

Usage

    ($u, $v) = bbuv($T); CIE UCS 1960 of black body radiator

Examples

XYZ2ucs

This function converts XYZ values to CIE UCS 1960 coordinates.

Usage

    ($u, $v) = XYZ2ucs(@XYZ); # CIE UCS 1960

Examples

xy2ucs

This function converts chromaticity values to CIE UCS 1960 coordinates.

Usage

    ($u, $v) = xy2ucs(@xy); # CIE UCS 1960

Examples

daylight

This function computes the SPD of CIE daylight at a given correlated color temperature.

Usage

    ($range, $spd) = daylight($cct); range and SPD of daylight

Examples

Interpolation functions

linear

This function interpolates a vector, using linear approximation.

Usage

    $vec_out = linear($vec_in, $range_in, $range_out); # interpolate a vector (linear)

Examples

linear_matrix

This function computes an interpolation matrix, using linear approximation.

Usage

    $matrix = linear_matrix($range_in, $range_out); # make interpolating matrix (linear)

Examples

cspline

This function interpolates a vector, using cubic spline approximation.

Usage

    $vec_out = cspline($vec_in, $range_in, $range_out); # interpolate a vector (natural cubic spline)

Examples

cspline_matrix

This function computes an interpolation matrix, using cubic spline approximation.

Usage

    $matrix = cspline_matrix($range_in, $range_out); # make interpolating matrix (natural cubic spline)

Examples

lagrange

This function interpolates a vector, using Lagrange approximation.

Usage

    $vec_out = lagrange($vec_in, $range_in, $range_out); # interpolate a vector (Lagrange, ASTM E 2022)

Examples

lagrange_matrix

This function computes an interpolation matrix, using Lagrange approximation.

Usage

    $matrix = lagrange_matrix($range_in, $range_out); # make interpolating matrix (Lagrange, ASTM E 2022)

Examples

Vector functions

dotProduct

This function computes the dot product of two vectors.

Usage

    $scalar = dotProduct($vec1, $vec2); # vector dot product

Examples

crossProduct

This function computes the cross product of two vectors.

Usage

    $vector = crossProduct($vec1, $vec2); # vector cross product

Examples

Utility functions

flatten

This function flattens an array structure.

Usage

    $vector = flatten($structure); # flatten an array structure

Examples

clip_struct

This function clips all of the values within an array structure.

Usage

    clip_struct($structure); # clip each element of an array structure

Examples

round

This function rounds off a value to the nearest integer.

Usage

    $integer = round($value); # round off value to nearest integer (+/-)

Examples

s15f162v

This function converts a vector from ICC s15Fixed16Number encoding.

Usage

    $vector = s15f162v($s15f16); # convert from s15Fixed16Number vector

Examples

v2s15f16

This function converts a vector to ICC s15Fixed16Number encoding.

Usage

    $s15f16 = v2s15f16($vector); # convert to s15Fixed16Number vector

Examples

makeProfileFolder

This function makes a folder for saving ICC profiles.

Usage

    (profiles_folder_path, directory_segs, customer, job) = makeProfileFolder(file/folder_path); # make folder for profiles
    (profiles_folder_path, directory_segs, customer, job) = makeProfileFolder(file/folder_path, alias_folder_path);

Examples

getICCPath

This function gets the path to the 'ICC' distribution folder. The optional parameter is appended to the path.

Usage

    $path = getICCPath(); # get path to 'ICC' distribution folder
    $path = getICCPath(sub_path); # get path to some item within the 'ICC' distribution folder

Examples

    $path = getICCPath(); # get path to 'ICC' folder
    $path = getICCPath('Data'); # get path to 'ICC/Data' folder
    $path = getICCPath('Data/ASTM_E308_data.yml'); # get path to 'ICC/Data/ASTM_E308_data.yml' file

filterPath

This function replaces a leading '~' with the user's home path. For non-Windows OS, the '\' character (escape) is removed. For Windows OS, '/' character is replaced by '\'.

Usage

    filterPath($path);

Examples

    $path = '~/Desktop/test.txt';
    filterPath($path);
    print "$path\n";

    $path = 'name\ with\ spaces.txt';
    filterPath($path);
    print "$path\n";

setFile

This function sets Mac OSX creator and file type.

Usage

    setFile(path_to_file, creator, type); # set Mac OSX creator and file type (deprecated by Apple)

Examples

parse_tokens

This function splits a string of tokens, and parses any parameters using the 'eval' function. It provides a convenient user interface for selecting an assortment of items, with optional parameters. The parameters can be any valid Perl expression, including scalars, anonymous arrays, and anonymous hashes. Expressions may also contain functions and global variables.

The function returns an array reference. The array contains the tokens, interspersed with the evaluated parameters. A parameter group may contain more than one parameter. So, each group is an array reference. See the example below.

Usage

    $array_ref = parse_tokens($token_string);

Examples

    $tokens = parse_tokens("option1, option2(25), option3([1, 2, 3]), option4({'key' => 99})");
    print Dumper($tokens);

produces this output,

    $VAR1 = [
          'option1',
          'option2',
          [
            25
          ],
          'option3',
          [
            [
              1,
              2,
              3
            ]
          ],
          'option4',
          [
            {
              'key' => 99
            }
          ]
        ];

Parameter testing functions

is_vector

This function tests if the parameter is a vector. Elements may be numeric or undef.

Usage

    $flag = is_vector($vec); # test if parameter is a vector

Examples

    print is_vector([]); # true
    print is_vector({}); # false
    print is_vector([1, 2, 3]); # true
    print is_vector([undef, 2, 3]); # true
    print is_vector(['xxx', 2, 3]); # false

is_num_vector

This function tests if the parameter is a vector. Elements must be numeric.

Usage

    $flag = is_num_vector($vec); # test if parameter is a vector

Examples

    print is_num_vector([]); # true
    print is_num_vector({}); # false
    print is_num_vector([1, 2, 3]); # true
    print is_num_vector([undef, 2, 3]); # false
    print is_num_vector(['xxx', 2, 3]); # false

is_matrix

This function tests if the parameter is a matrix. Elements may be numeric or undef.

Usage

    $flag = is_matrix($mat); # test if parameter is a matrix

Examples

    print is_matrix([]); # true
    print is_matrix({}); # false
    print is_matrix([[]]); # true
    print is_num_matrix([{}]); # false
    print is_matrix([[1, 2, 3]]); # true
    print is_matrix(Math::Matrix->new([1, 2, 3])); # true
    print is_matrix([[undef, 2, 3]]); # true
    print is_matrix([['xxx', 2, 3]]); # false

is_num_matrix

This function tests if the parameter is a matrix. Elements must be numeric.

Usage

    $flag = is_num_matrix($mat); # test if parameter is a matrix

Examples

    print is_num_matrix([]); # true
    print is_num_matrix({}); # false
    print is_num_matrix([[]]); # true
    print is_num_matrix([{}]); # false
    print is_num_matrix([[1, 2, 3]]); # true
    print is_num_matrix(Math::Matrix->new([1, 2, 3])); # true
    print is_num_matrix([[undef, 2, 3]]); # false
    print is_num_matrix([['xxx', 2, 3]]); # false

CONSTANTS

Perl handling of constants

Perl's constant pragma is used to make the following constants. These are actually subroutines, created at compile time. Their values cannot be altered, so they are effectively constants. Because they are subroutines, there are no sigils, which occasionally leads to ambiguity. This can be resolved by enclosing the constant in parentheses (see example below).

D50

D50 illuminant XYZ values, as specified by the ICC (based on the CIE 1931 2 degree observer)

Note that the ICC values for D50 ([96.42, 100, 82.49]) are slightly different from the CIE values ([96.42, 100, 82.51]).

Examples

    $XYZ = D50; # vector

    $Z = D50->[2]; # Z value

    @XYZ = @{(D50)}; # array, note the parentheses

    @XYZ = Lab2XYZ(@Lab, D50); # use as white point to change encoding

d50

D50 illuminant XYZ values, encoded as 32-bit ICC XYZNumber, [0.9624, 1, 0.8249].

d50P

D50 illuminant XYZ values, encoded as 16-bit ICC XYZ, approximately [0.48211, 0.50001, 0.41246].

PI

circumference of a unit circle, approximately 3.14159

radian

degrees in a radian, approximately 57.29578

ln10

natural logarithm of 10, approximately 2.30258

SEE ALSO

ASTM Standards

ASTM E 2022 Standard Practice for Calculation of Weighting Factors for Tristimulus Integration

CIE Standards

CIE 15 Colorimetry

DIN Standards

DIN 6176 Colorimetric evaluation of colour differences of surface colours according to DIN99 formula

ICC Specification

The ICC (International Color Consortium) maintains a web site at http://www.color.org The ICC specification and related materials may be downloaded from this web site.

The ICC specification is also published as ISO 15076-1.

ISO Standards

ISO 15076-1 Image technology colour management — Architecture, profile format and data structure — Part 1: Based on ICC.1:2010

LICENSE

Programs in this distribution, authored by William B. Birkett, are licensed under the GNU General Public License, v3.

See http://www.gnu.org/licenses/gpl.html for license details.

AUTHOR

William B. Birkett, <wbirkett@doplganger.com>

COPYRIGHT

Copyright © 2004-2018 by William B. Birkett

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