def test_averaging(self):
a = np.array([[1, 2, 2, 1], [3, 2, 8, 1], [0, 0, 2, 2], [0, 4, 2, 2]])
config = Configuration(width=123,
height=854,
block_size=2,
dct_size=2,
transform='DCT',
quantization=None)
sub_sampling = SubSampling(config)
res = sub_sampling.execute(a)
self.assertEqual(res.shape, (2, 2))
self.assertEqual(res[0][0], 2)
self.assertEqual(res[0][1], 3)
self.assertEqual(res[1][0], 1)
self.assertEqual(res[1][1], 2)
config = Configuration(width=123,
height=854,
block_size=4,
dct_size=2,
transform='DCT',
quantization=None)
sub_sampling = SubSampling(config)
res = sub_sampling.execute(a)
self.assertEqual(res.shape, (1, 1))
self.assertEqual(res[0][0], 2)
def test_without_subsampling(self):
original = np.arange(6).reshape(2, 3)
config = Configuration(width=3, height=2, block_size=1)
restored = decompress_band(compress_band(original, config), config)
self.assertTrue(np.allclose(original, restored, rtol=0.000001))
def test_compress_and_decompress_on_array(self):
original = np.arange(128).reshape(8, 16)
config = Configuration(width=16, height=8, block_size=3)
restored = decompress_band(compress_band(original, config), config)
self.assertTrue(np.allclose(original, restored, rtol=1))
def test_decode_encoded_blocks(self):
a = self.array
config = Configuration(width=3, height=9, block_size=1, dct_size=3)
rle = RunLengthEncoding(config=config)
res = rle.invert(rle.execute(a))
self.assertEqual(res.tolist(), a.tolist())
def test_fourier_transform_option(self):
original = np.arange(128).reshape(8, 16)
config = Configuration(width=16,
height=8,
block_size=3,
transform='DFT')
restored = decompress_band(compress_band(original, config), config)
self.assertTrue(np.allclose(original, restored, rtol=1))
def test_restore_zigzag(self):
a = np.arange(32).reshape(4, 8)
config = Configuration(width=8, height=4, block_size=1, dct_size=2)
zigzag_step = ZigzagOrder(config)
res = zigzag_step.invert(zigzag_step.execute(a))
self.assertEqual(res.shape, a.shape)
self.assertEqual(res.tolist(), a.tolist())
def test_zigzag_order_step(self):
a = np.arange(16).reshape(4, 4)
config = Configuration(width=4, height=4, block_size=1, dct_size=2)
zigzag_step = ZigzagOrder(config)
res = zigzag_step.execute(a)
expected = np.array([[[0, 1, 4, 5], [2, 3, 6, 7]],
[[8, 9, 12, 13], [10, 11, 14, 15]]])
self.assertTupleEqual(res.shape, (2, 2, 4))
self.assertEqual(res.tolist(), expected.tolist())
def test_preserves_allowed_range(self):
original = np.array([[220, 255, 123, 205], [255, 255, 112, 10],
[15, 51, 83, 221], [239, 73, 62, 22]])
self.assertTrue(np.all(original < 256))
self.assertTrue(np.all(original > -1))
config = Configuration(width=4,
height=4,
block_size=1,
dct_size=2,
quantization=QuantizationMethod('divide',
divisor=129))
restored = decompress_band(compress_band(original, config), config)
self.assertTrue(np.all(restored < 256))
self.assertTrue(np.all(restored > -1))
def test_create_and_read_header(self):
q = QuantizationMethod('qtable')
config = Configuration(width=320,
height=400,
block_size=4,
dct_size=8,
transform='DFT',
quantization=q)
res = file_format.get_header(file_format.create_header(config))
self.assertEqual(config.width, res.width)
self.assertEqual(config.height, res.height)
self.assertEqual(config.block_size, res.block_size)
self.assertEqual(config.dct_size, res.dct_size)
self.assertEqual(config.transform, res.transform)
self.assertEqual(res.quantization.name, 'qtable')
def test_create_with_different_quantization_method(self):
q = QuantizationMethod('divide', divisor=93)
config = Configuration(width=320,
height=400,
block_size=44,
dct_size=16,
transform='DCT',
quantization=q)
res = file_format.get_header(file_format.create_header(config))
self.assertEqual(res.width, 320)
self.assertEqual(res.height, 400)
self.assertEqual(res.block_size, 44)
self.assertEqual(res.dct_size, 16)
self.assertEqual(res.transform, 'DCT')
self.assertEqual(res.quantization.name, 'divide')
self.assertEqual(res.quantization.params, {'divisor': 93})
def test_generate_and_read_data(self):
q = QuantizationMethod('divide', divisor=93)
config = Configuration(width=320,
height=400,
block_size=44,
dct_size=16,
transform='DCT',
quantization=q)
data = CompressedData(y=bytes([4, 8, 15, 16, 23, 42]),
cb=bytes([1, 2, 3, 4, 5]),
cr=bytes([10]))
res = file_format.generate_data(config, data)
read_config, read_data = file_format.read_data(res)
self.assertEqual(read_config.dct_size, 16)
self.assertEqual(read_data.y, bytes([4, 8, 15, 16, 23, 42]))
self.assertEqual(read_data.cb, bytes([1, 2, 3, 4, 5]))
self.assertEqual(read_data.cr, bytes([10]))
def compress(input_fname,
output_fname,
block_size=4,
dct_size=8,
transform='DCT',
quantization=None):
im = Image.open(input_fname).convert('YCbCr')
config = Configuration(width=im.width,
height=im.height,
block_size=block_size,
dct_size=dct_size,
transform=transform,
quantization=quantization)
jpeg = Jpeg(config)
compressed_bytes = jpeg.compress(im)
with open(output_fname, 'wb') as f:
f.write(compressed_bytes)
def test_with_1pixel_blocks(self):
original = np.arange(64).reshape(8, 8)
config = Configuration(width=8, height=8, block_size=1, dct_size=1)
restored = decompress_band(compress_band(original, config), config)
self.assertTrue(np.allclose(original, restored, rtol=0.000001))