libvips/test/test_histogram.py

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#!/usr/bin/python
import unittest
import math
#import logging
#logging.basicConfig(level = logging.DEBUG)
import gi
gi.require_version('Vips', '8.0')
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from gi.repository import Vips
Vips.leak_set(True)
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# an expanding zip ... if either of the args is a scalar or a one-element list,
# duplicate it down the other side
def zip_expand(x, y):
# handle singleton list case
if isinstance(x, list) and len(x) == 1:
x = x[0]
if isinstance(y, list) and len(y) == 1:
y = y[0]
if isinstance(x, list) and isinstance(y, list):
return list(zip(x, y))
elif isinstance(x, list):
return [[i, y] for i in x]
elif isinstance(y, list):
return [[x, j] for j in y]
else:
return [[x, y]]
class TestHistogram(unittest.TestCase):
# test a pair of things which can be lists for approx. equality
def assertAlmostEqualObjects(self, a, b, places = 4, msg = ''):
# print 'assertAlmostEqualObjects %s = %s' % (a, b)
for x, y in zip_expand(a, b):
self.assertAlmostEqual(x, y, places = places, msg = msg)
def test_hist_cum(self):
im = Vips.Image.identity()
sum = im.avg() * 256
cum = im.hist_cum()
p = cum(255, 0)
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self.assertEqual(p[0], sum)
def test_hist_equal(self):
im = Vips.Image.new_from_file("images/IMG_4618.jpg")
im2 = im.hist_equal()
self.assertEqual(im.width, im2.width)
self.assertEqual(im.height, im2.height)
self.assertTrue(im.avg() < im2.avg())
self.assertTrue(im.deviate() < im2.deviate())
def test_hist_ismonotonic(self):
im = Vips.Image.identity()
self.assertTrue(im.hist_ismonotonic())
def test_hist_local(self):
im = Vips.Image.new_from_file("images/IMG_4618.jpg")
im2 = im.hist_local(10, 10)
self.assertEqual(im.width, im2.width)
self.assertEqual(im.height, im2.height)
self.assertTrue(im.avg() < im2.avg())
self.assertTrue(im.deviate() < im2.deviate())
def test_hist_match(self):
im = Vips.Image.identity()
im2 = Vips.Image.identity()
matched = im.hist_match(im2)
self.assertEqual((im - matched).abs().max(), 0.0)
def test_hist_norm(self):
im = Vips.Image.identity()
im2 = im.hist_norm()
self.assertEqual((im - im2).abs().max(), 0.0)
def test_hist_plot(self):
im = Vips.Image.identity()
im2 = im.hist_plot()
self.assertEqual(im2.width, 256)
self.assertEqual(im2.height, 256)
self.assertEqual(im2.format, Vips.BandFormat.UCHAR)
self.assertEqual(im2.bands, 1)
def test_hist_map(self):
im = Vips.Image.identity()
im2 = im.maplut(im)
self.assertEqual((im - im2).abs().max(), 0.0)
def test_percent(self):
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im = Vips.Image.new_from_file("images/IMG_4618.jpg").extract_band(1)
pc = im.percent(90)
msk = im <= pc
n_set = (msk.avg() * msk.width * msk.height) / 255.0
pc_set = 100 * n_set / (msk.width * msk.height)
self.assertAlmostEqual(pc_set, 90, places = 0)
def test_hist_entropy(self):
im = Vips.Image.new_from_file("images/IMG_4618.jpg").extract_band(1)
ent = im.hist_find().hist_entropy()
self.assertAlmostEqual(ent, 4.367, places = 3)
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def test_stdif(self):
im = Vips.Image.new_from_file("images/IMG_4618.jpg")
im2 = im.stdif(10, 10)
self.assertEqual(im.width, im2.width)
self.assertEqual(im.height, im2.height)
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# new mean should be closer to target mean
self.assertTrue(abs(im.avg() - 128) > abs(im2.avg() - 128))
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if __name__ == '__main__':
unittest.main()