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Image.Open() and 16bit gray images - int32 output #3041

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lschaupp opened this issue Mar 14, 2018 · 4 comments
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Image.Open() and 16bit gray images - int32 output #3041

lschaupp opened this issue Mar 14, 2018 · 4 comments
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@lschaupp
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If you use Image.Open("test.png") on a uint16 png depth image
-> Pillow opens is with the mode "I" which is int32.
I'm wondering if this behaviour is intentional?
I guess there is no information loss involved - but why would you do this conversion to int32 instead
of the uint16?

Thanks!
@wiredfool
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There's better support for image operations on int32 images than int16, especially for signed 16 bit images.

@anntzer
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anntzer commented Sep 4, 2019 •
edited by radarhere

Is there any change this issue can be revisited? AFAICT Pillow's TIFF and JPEG handlers, for example, will happily open 16-bit data without upcasting, so I don't see why the PNG handler can't do the same.

anntzer added a commit to anntzer/matplotlib that referenced this issue Sep 4, 2019
@anntzer
WIP: switch to using pillow for png as well.
9098297 
The version check in _has_pil (pillow>=3.4) was dropped as the oldest
Pillow that supports Py3.6 (the oldest Python supported by Matplotlib)
is 4.0 anyways.

- PIL returns uint16 images as int32
  (python-pillow/Pillow#3041); we could adopt
  imageio's dtype correcting code if desired.
anntzer added a commit to anntzer/matplotlib that referenced this issue Sep 4, 2019
@anntzer
WIP: switch to using pillow for png as well.
013ce89 
The version check in _has_pil (pillow>=3.4) was dropped as the oldest
Pillow that supports Py3.6 (the oldest Python supported by Matplotlib)
is 4.0 anyways.

- PIL returns uint16 images as int32
  (python-pillow/Pillow#3041); we could adopt
  imageio's dtype correcting code if desired.
@anntzer anntzer mentioned this issue Sep 4, 2019
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@radarhere radarhere mentioned this issue Sep 4, 2019
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@radarhere radarhere mentioned this issue Mar 2, 2022
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@radarhere
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This has been revisited in the form of #3796

@radarhere radarhere mentioned this issue Nov 29, 2022
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@radarhere radarhere mentioned this issue Mar 8, 2023
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@radarhere radarhere mentioned this issue Mar 2, 2024
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@radarhere
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I've created PR #7849 to address this.

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@wiredfool @aclark4life @anntzer @radarhere @lschaupp