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;;; lcms-tests.el --- tests for Little CMS interface -*- lexical-binding: t -*-
;; Copyright (C) 2017-2021 Free Software Foundation, Inc.
;; Maintainer: emacs-devel@gnu.org
;; This file is part of GNU Emacs.
;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.
;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
;;; Commentary:
;; Some reference values computed using the colorspacious python
;; library, assimilated from its test suite, or adopted from its
;; aggregation of gold values.
;; See https://colorspacious.readthedocs.io/en/v1.1.0/ and
;; https://github.com/njsmith/colorspacious
;; Other references:
;; http://www.babelcolor.com/index_htm_files/A%20review%20of%20RGB%20color%20spaces.pdf
;;; Code:
(require 'ert)
(require 'color)
(declare-function lcms-jab->jch "lcms.c")
(declare-function lcms-jch->jab "lcms.c")
(declare-function lcms-xyz->jch "lcms.c")
(declare-function lcms-jch->xyz "lcms.c")
(declare-function lcms-temp->white-point "lcms.c")
(declare-function lcms-cam02-ucs "lcms.c")
(defconst lcms-colorspacious-d65 '(0.95047 1.0 1.08883)
"D65 white point from colorspacious.")
(defun lcms-approx-p (a b &optional delta)
"Check if A and B are within relative error DELTA of one another.
B is considered the exact value."
(> (or delta 0.001) (abs (1- (/ a b)))))
(defun lcms-triple-approx-p (a b &optional delta)
"Like `lcms-approx-p' except for color triples."
(pcase-let ((`(,a1 ,a2 ,a3) a)
(`(,b1 ,b2 ,b3) b))
(and (lcms-approx-p a1 b1 delta)
(lcms-approx-p a2 b2 delta)
(lcms-approx-p a3 b3 delta))))
(defun lcms-rgb255->xyz (rgb)
"Return XYZ tristimulus values corresponding to RGB."
(let ((rgb1 (mapcar (lambda (x) (/ x 255.0)) rgb)))
(apply #'color-srgb-to-xyz rgb1)))
(ert-deftest lcms-cri-cam02-ucs ()
"Test use of `lcms-cam02-ucs'."
(skip-unless (featurep 'lcms2))
(should-error (lcms-cam02-ucs '(0 0 0) '(0 0 0) "error"))
(should-error (lcms-cam02-ucs '(0 0 0) 'error))
(should-not
(lcms-approx-p
(let ((wp '(0.44757 1.0 0.40745)))
(lcms-cam02-ucs '(0.5 0.5 0.5) '(0 0 0) wp))
(lcms-cam02-ucs '(0.5 0.5 0.5) '(0 0 0))))
(should (eql 0.0 (lcms-cam02-ucs '(0.5 0.5 0.5) '(0.5 0.5 0.5))))
(should
(lcms-approx-p (lcms-cam02-ucs lcms-colorspacious-d65
'(0 0 0)
lcms-colorspacious-d65)
100.0)))
(ert-deftest lcms-whitepoint ()
"Test use of `lcms-temp->white-point'."
(skip-unless (featurep 'lcms2))
(should-error (lcms-temp->white-point 3999))
(should-error (lcms-temp->white-point 25001))
;; D55
(should
(lcms-triple-approx-p
(apply #'color-xyz-to-xyy (lcms-temp->white-point 5503))
'(0.33242 0.34743 1.0)))
;; D65
(should
(lcms-triple-approx-p
(apply #'color-xyz-to-xyy (lcms-temp->white-point 6504))
'(0.31271 0.32902 1.0)))
;; D75
(should
(lcms-triple-approx-p
(apply #'color-xyz-to-xyy (lcms-temp->white-point 7504))
'(0.29902 0.31485 1.0))))
(ert-deftest lcms-roundtrip ()
"Test accuracy of converting to and from different color spaces."
(skip-unless (featurep 'lcms2))
(should
(let ((color '(.5 .3 .7)))
(lcms-triple-approx-p (lcms-jch->xyz (lcms-xyz->jch color))
color
0.0001)))
(should
(let ((color '(.8 -.2 .2)))
(lcms-triple-approx-p (lcms-jch->jab (lcms-jab->jch color))
color
0.0001))))
(ert-deftest lcms-ciecam02-gold ()
"Test CIE CAM02 JCh gold values."
(skip-unless (featurep 'lcms2))
(should
(lcms-triple-approx-p
(lcms-xyz->jch '(0.1931 0.2393 0.1014)
'(0.9888 0.900 0.3203)
'(18 200 1 1.0))
'(48.0314 38.7789 191.0452)
0.02))
(should
(lcms-triple-approx-p
(lcms-xyz->jch '(0.1931 0.2393 0.1014)
'(0.9888 0.90 0.3203)
'(18 20 1 1.0))
'(47.6856 36.0527 185.3445)
0.09)))
(ert-deftest lcms-dE-cam02-ucs-silver ()
"Test CRI-CAM02-UCS deltaE metric values from colorspacious."
(skip-unless (featurep 'lcms2))
(should
(lcms-approx-p
(lcms-cam02-ucs (lcms-rgb255->xyz '(173 52 52))
(lcms-rgb255->xyz '(59 120 51))
lcms-colorspacious-d65
(list 20 (/ 64 float-pi 5) 1 1))
44.698469808449964
0.03))
(should
(lcms-approx-p
(lcms-cam02-ucs (lcms-rgb255->xyz '(69 100 52))
(lcms-rgb255->xyz '(59 120 51))
lcms-colorspacious-d65
(list 20 (/ 64 float-pi 5) 1 1))
8.503323264883667
0.04)))
(ert-deftest lcms-jmh->cam02-ucs-silver ()
"Compare JCh conversion to CAM02-UCS to values from colorspacious."
(skip-unless (featurep 'lcms2))
(should
(lcms-triple-approx-p (lcms-jch->jab '(50 20 10))
'(62.96296296 16.22742674 2.86133316)
0.05))
(should
(lcms-triple-approx-p (lcms-jch->jab '(10 60 100))
'(15.88785047 -6.56546789 37.23461867)
0.04)))
;;; lcms-tests.el ends here
|
