from PIL import Image, ImageMath, ImageMode from .helper import PillowTestCase, convert_to_comparable class TestImageReduce(PillowTestCase): # There are several internal implementations remarkable_factors = [ # special implementations 1, 2, 3, 4, 5, 6, # 1xN implementation (1, 2), (1, 3), (1, 4), (1, 7), # Nx1 implementation (2, 1), (3, 1), (4, 1), (7, 1), # general implementation with different paths (4, 6), (5, 6), (4, 7), (5, 7), (19, 17), ] @classmethod def setUpClass(cls): cls.gradients_image = Image.open("Tests/images/radial_gradients.png") cls.gradients_image.load() def test_args_factor(self): im = Image.new("L", (10, 10)) self.assertEqual((4, 4), im.reduce(3).size) self.assertEqual((4, 10), im.reduce((3, 1)).size) self.assertEqual((10, 4), im.reduce((1, 3)).size) with self.assertRaises(ValueError): im.reduce(0) with self.assertRaises(TypeError): im.reduce(2.0) with self.assertRaises(ValueError): im.reduce((0, 10)) def test_args_box(self): im = Image.new("L", (10, 10)) self.assertEqual((5, 5), im.reduce(2, (0, 0, 10, 10)).size) self.assertEqual((1, 1), im.reduce(2, (5, 5, 6, 6)).size) with self.assertRaises(TypeError): im.reduce(2, "stri") with self.assertRaises(TypeError): im.reduce(2, 2) with self.assertRaises(ValueError): im.reduce(2, (0, 0, 11, 10)) with self.assertRaises(ValueError): im.reduce(2, (0, 0, 10, 11)) with self.assertRaises(ValueError): im.reduce(2, (-1, 0, 10, 10)) with self.assertRaises(ValueError): im.reduce(2, (0, -1, 10, 10)) with self.assertRaises(ValueError): im.reduce(2, (0, 5, 10, 5)) with self.assertRaises(ValueError): im.reduce(2, (5, 0, 5, 10)) def test_unsupported_modes(self): im = Image.new("P", (10, 10)) with self.assertRaises(ValueError): im.reduce(3) im = Image.new("1", (10, 10)) with self.assertRaises(ValueError): im.reduce(3) im = Image.new("I;16", (10, 10)) with self.assertRaises(ValueError): im.reduce(3) def get_image(self, mode): mode_info = ImageMode.getmode(mode) if mode_info.basetype == "L": bands = [self.gradients_image] for _ in mode_info.bands[1:]: # rotate previous image band = bands[-1].transpose(Image.ROTATE_90) bands.append(band) # Correct alpha channel to exclude completely transparent pixels. # Low alpha values also emphasize error after alpha multiplication. if mode.endswith("A"): bands[-1] = bands[-1].point(lambda x: int(85 + x / 1.5)) im = Image.merge(mode, bands) else: assert len(mode_info.bands) == 1 im = self.gradients_image.convert(mode) # change the height to make a not square image return im.crop((0, 0, im.width, im.height - 5)) def compare_reduce_with_box(self, im, factor): box = (11, 13, 146, 164) reduced = im.reduce(factor, box=box) reference = im.crop(box).reduce(factor) self.assertEqual(reduced, reference) def compare_reduce_with_reference(self, im, factor, average_diff=0.4, max_diff=1): """Image.reduce() should look very similar to Image.resize(BOX). A reference image is compiled from a large source area and possible last column and last row. +-----------+ |..........c| |..........c| |..........c| |rrrrrrrrrrp| +-----------+ """ reduced = im.reduce(factor) if not isinstance(factor, (list, tuple)): factor = (factor, factor) reference = Image.new(im.mode, reduced.size) area_size = (im.size[0] // factor[0], im.size[1] // factor[1]) area_box = (0, 0, area_size[0] * factor[0], area_size[1] * factor[1]) area = im.resize(area_size, Image.BOX, area_box) reference.paste(area, (0, 0)) if area_size[0] < reduced.size[0]: self.assertEqual(reduced.size[0] - area_size[0], 1) last_column_box = (area_box[2], 0, im.size[0], area_box[3]) last_column = im.resize((1, area_size[1]), Image.BOX, last_column_box) reference.paste(last_column, (area_size[0], 0)) if area_size[1] < reduced.size[1]: self.assertEqual(reduced.size[1] - area_size[1], 1) last_row_box = (0, area_box[3], area_box[2], im.size[1]) last_row = im.resize((area_size[0], 1), Image.BOX, last_row_box) reference.paste(last_row, (0, area_size[1])) if area_size[0] < reduced.size[0] and area_size[1] < reduced.size[1]: last_pixel_box = (area_box[2], area_box[3], im.size[0], im.size[1]) last_pixel = im.resize((1, 1), Image.BOX, last_pixel_box) reference.paste(last_pixel, area_size) self.assert_compare_images(reduced, reference, average_diff, max_diff) def assert_compare_images(self, a, b, max_average_diff, max_diff=255): self.assertEqual(a.mode, b.mode, "got mode %r, expected %r" % (a.mode, b.mode)) self.assertEqual(a.size, b.size, "got size %r, expected %r" % (a.size, b.size)) a, b = convert_to_comparable(a, b) bands = ImageMode.getmode(a.mode).bands for band, ach, bch in zip(bands, a.split(), b.split()): ch_diff = ImageMath.eval("convert(abs(a - b), 'L')", a=ach, b=bch) ch_hist = ch_diff.histogram() average_diff = sum(i * num for i, num in enumerate(ch_hist)) / float( a.size[0] * a.size[1] ) self.assertGreaterEqual( max_average_diff, average_diff, ( "average pixel value difference {:.4f} > expected {:.4f} " "for '{}' band" ).format(average_diff, max_average_diff, band), ) last_diff = [i for i, num in enumerate(ch_hist) if num > 0][-1] self.assertGreaterEqual( max_diff, last_diff, "max pixel value difference {} > expected {} for '{}' band".format( last_diff, max_diff, band ), ) def test_mode_L(self): im = self.get_image("L") for factor in self.remarkable_factors: self.compare_reduce_with_reference(im, factor) self.compare_reduce_with_box(im, factor) def test_mode_LA(self): im = self.get_image("LA") for factor in self.remarkable_factors: self.compare_reduce_with_reference(im, factor, 0.8, 5) # With opaque alpha, error should be way smaller im.putalpha(Image.new("L", im.size, 255)) for factor in self.remarkable_factors: self.compare_reduce_with_reference(im, factor) self.compare_reduce_with_box(im, factor) def test_mode_La(self): im = self.get_image("La") for factor in self.remarkable_factors: self.compare_reduce_with_reference(im, factor) self.compare_reduce_with_box(im, factor) def test_mode_RGB(self): im = self.get_image("RGB") for factor in self.remarkable_factors: self.compare_reduce_with_reference(im, factor) self.compare_reduce_with_box(im, factor) def test_mode_RGBA(self): im = self.get_image("RGBA") for factor in self.remarkable_factors: self.compare_reduce_with_reference(im, factor, 0.8, 5) # With opaque alpha, error should be way smaller im.putalpha(Image.new("L", im.size, 255)) for factor in self.remarkable_factors: self.compare_reduce_with_reference(im, factor) self.compare_reduce_with_box(im, factor) def test_mode_RGBa(self): im = self.get_image("RGBa") for factor in self.remarkable_factors: self.compare_reduce_with_reference(im, factor) self.compare_reduce_with_box(im, factor) def test_mode_I(self): im = self.get_image("I") for factor in self.remarkable_factors: self.compare_reduce_with_reference(im, factor) self.compare_reduce_with_box(im, factor) def test_mode_F(self): im = self.get_image("F") for factor in self.remarkable_factors: self.compare_reduce_with_reference(im, factor, 0, 0) self.compare_reduce_with_box(im, factor)