# vim: set fileencoding=utf-8 :
import pytest
import pyvips
from helpers import JPEG_FILE, SRGB_FILE, colour_colourspaces, \
mono_colourspaces, assert_almost_equal_objects, skip_if_no
class TestColour:
def test_colourspace(self):
# mid-grey in Lab ... put 42 in the extra band, it should be copied
# unmodified
test = pyvips.Image.black(100, 100) + [50, 0, 0, 42]
test = test.copy(interpretation=pyvips.Interpretation.LAB)
# a long series should come in a circle
im = test
for col in colour_colourspaces + [pyvips.Interpretation.LAB]:
im = im.colourspace(col)
assert im.interpretation == col
for i in range(0, 4):
min_l = im.extract_band(i).min()
max_h = im.extract_band(i).max()
assert pytest.approx(min_l) == max_h
pixel = im(10, 10)
assert pytest.approx(pixel[3], 0.01) == 42
# alpha won't be equal for RGB16, but it should be preserved if we go
# there and back
im = im.colourspace(pyvips.Interpretation.RGB16)
im = im.colourspace(pyvips.Interpretation.LAB)
before = test(10, 10)
after = im(10, 10)
assert_almost_equal_objects(before, after, threshold=0.1)
# go between every pair of colour spaces
for start in colour_colourspaces:
for end in colour_colourspaces:
im = test.colourspace(start)
im2 = im.colourspace(end)
im3 = im2.colourspace(pyvips.Interpretation.LAB)
before = test(10, 10)
after = im3(10, 10)
assert_almost_equal_objects(before, after, threshold=0.1)
# test Lab->XYZ on mid-grey
# checked against http://www.brucelindbloom.com
im = test.colourspace(pyvips.Interpretation.XYZ)
after = im(10, 10)
assert_almost_equal_objects(after, [17.5064, 18.4187, 20.0547, 42])
# grey->colour->grey should be equal
for mono_fmt in mono_colourspaces:
test_grey = test.colourspace(mono_fmt)
im = test_grey
for col in colour_colourspaces + [mono_fmt]:
im = im.colourspace(col)
assert im.interpretation == col
[before, alpha_before] = test_grey(10, 10)
[after, alpha_after] = im(10, 10)
assert abs(alpha_after - alpha_before) < 1
if mono_fmt == pyvips.Interpretation.GREY16:
# GREY16 can wind up rather different due to rounding
assert abs(after - before) < 30
else:
# but 8-bit we should hit exactly
assert abs(after - before) < 1
# we should be able to go from cmyk to any 3-band space and back again,
# approximately
cmyk = test.colourspace(pyvips.Interpretation.CMYK)
for end in colour_colourspaces:
im = cmyk.colourspace(end)
im2 = im.colourspace(pyvips.Interpretation.CMYK)
before = cmyk(10, 10)
after = im2(10, 10)
assert_almost_equal_objects(before, after, threshold=10)
# test results from Bruce Lindbloom's calculator:
# http://www.brucelindbloom.com
def test_dE00(self):
# put 42 in the extra band, it should be copied unmodified
reference = pyvips.Image.black(100, 100) + [50, 10, 20, 42]
reference = reference.copy(interpretation=pyvips.Interpretation.LAB)
sample = pyvips.Image.black(100, 100) + [40, -20, 10]
sample = sample.copy(interpretation=pyvips.Interpretation.LAB)
difference = reference.dE00(sample)
result, alpha = difference(10, 10)
assert pytest.approx(result, 0.001) == 30.238
assert pytest.approx(alpha, 0.001) == 42.0
def test_dE76(self):
# put 42 in the extra band, it should be copied unmodified
reference = pyvips.Image.black(100, 100) + [50, 10, 20, 42]
reference = reference.copy(interpretation=pyvips.Interpretation.LAB)
sample = pyvips.Image.black(100, 100) + [40, -20, 10]
sample = sample.copy(interpretation=pyvips.Interpretation.LAB)
difference = reference.dE76(sample)
result, alpha = difference(10, 10)
assert pytest.approx(result, 0.001) == 33.166
assert pytest.approx(alpha, 0.001) == 42.0
# the vips CMC calculation is based on distance in a colorspace
# derived from the CMC formula, so it won't match exactly ...
# see vips_LCh2CMC() for details
def test_dECMC(self):
reference = pyvips.Image.black(100, 100) + [50, 10, 20, 42]
reference = reference.copy(interpretation=pyvips.Interpretation.LAB)
sample = pyvips.Image.black(100, 100) + [55, 11, 23]
sample = sample.copy(interpretation=pyvips.Interpretation.LAB)
difference = reference.dECMC(sample)
result, alpha = difference(10, 10)
assert abs(result - 4.97) < 0.5
assert pytest.approx(alpha, 0.001) == 42.0
@skip_if_no("icc_import")
def test_icc(self):
test = pyvips.Image.new_from_file(JPEG_FILE)
im = test.icc_import().icc_export()
assert im.dE76(test).max() < 6
im = test.icc_import()
im2 = im.icc_export(depth=16)
assert im2.format == pyvips.BandFormat.USHORT
im3 = im2.icc_import()
assert (im - im3).abs().max() < 3
im = test.icc_import(intent=pyvips.Intent.ABSOLUTE)
im2 = im.icc_export(intent=pyvips.Intent.ABSOLUTE)
assert im2.dE76(test).max() < 6
im = test.icc_import()
im2 = im.icc_export(output_profile=SRGB_FILE)
im3 = im.colourspace(pyvips.Interpretation.SRGB)
assert im2.dE76(im3).max() < 6
before_profile = test.get("icc-profile-data")
im = test.icc_transform(SRGB_FILE)
after_profile = im.get("icc-profile-data")
im2 = test.icc_import()
im3 = im2.colourspace(pyvips.Interpretation.SRGB)
assert im.dE76(im3).max() < 6
assert len(before_profile) != len(after_profile)
im = test.icc_import(input_profile=SRGB_FILE)
im2 = test.icc_import()
assert 6 < im.dE76(im2).max()
im = test.icc_import(pcs=pyvips.PCS.XYZ)
assert im.interpretation == pyvips.Interpretation.XYZ
im = test.icc_import()
assert im.interpretation == pyvips.Interpretation.LAB
# even without lcms, we should have a working approximation
def test_cmyk(self):
test = pyvips.Image.new_from_file(JPEG_FILE)
im = test.colourspace("cmyk").colourspace("srgb")
before = test(150, 210)
after = im(150, 210)
assert_almost_equal_objects(before, after, threshold=10)
if __name__ == '__main__':
pytest.main()