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Add support for writing 16-bit greyscale images #1819

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Add support for writing 16-bit greyscale images #1819

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Binary file added Tests/images/uint16_greyscale.tif
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24 changes: 23 additions & 1 deletion Tests/test_file_tiff.py
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@
import struct

from helper import unittest, PillowTestCase, hopper, py3

import numpy as np
from PIL import Image, TiffImagePlugin

logger = logging.getLogger(__name__)
Expand Down Expand Up @@ -450,6 +450,28 @@ def test_save_tiff_with_jpegtables(self):
# Should not raise UnicodeDecodeError or anything else
im.save(outfile)

def test_save_greyscale_uint16_tiff(self):
'''
Save uint16 data as a greyscale uint16 TIFF.
'''
data = np.full([200, 200], 65535, np.uint16)
im = Image.fromarray(data)
outfile = self.tempfile("temp.tif")
im.save(outfile)

def test_roundtrip_greyscale_uint16_tiff(self):
'''
Confirm that all data saved to a uint16 TIFF is preserved.
Note: This will fail if test_save_greyscale_uint16_tiff() fails.
'''
data = np.full([200, 200], 65535, np.uint16)
im = Image.fromarray(data)
outfile = self.tempfile("temp.tif")
im.save(outfile)

out_im = Image.open(outfile)
self.assert_image_equal(im, out_im)

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@wiredfool wiredfool Apr 10, 2016

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This test doesn't actually test the code changes, as it doesn't run through any of the numpy code. It's only testing round tripping of a saved image.

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@mairsbw mairsbw Apr 10, 2016

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Why does numpy need to be involved? This is a uint16 TIFF that's being resaved. This test failed previously because it both threw a TypeError saying it could save uint16 TIFFs and because the data it saved was wrong, it only saved the image as a uint8 image. This test checks for both of those things.

if __name__ == '__main__':
unittest.main()

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