Pillow: 16 bit grayscale ome.tif from Leica LAS AF

Created on 5 Feb 2015 · 8Comments · Source: python-pillow/Pillow

I'm having trouble with saving a 16 bit grayscale TIFF as 16 bit PNG. The mode is set to I;16 by Pillow, which is an outmode as far as I can see: PngImagePlugin.py

Here is a file for testing: 16bit.ome.tif

This code will reproduce the error:

from PIL import Image
img = Image.open('16bit.ome.tif')
img.save('16bit.png')

A more verbose debugging is done here.

Documentation Question

Source

arve0

All 8 comments

Adding the error message:

---------------------------------------------------------------------------
OSError                                   Traceback (most recent call last)
<ipython-input-22-bed9526a441a> in <module>()
----> 1 i.save('test.png')

/Users/arve/.virtualenvs/3.4/lib/python3.4/site-packages/PIL/Image.py in save(self, fp, format, **params)
   1680 
   1681         try:
-> 1682             save_handler(self, fp, filename)
   1683         finally:
   1684             # do what we can to clean up

/Users/arve/.virtualenvs/3.4/lib/python3.4/site-packages/PIL/PngImagePlugin.py in _save(im, fp, filename, chunk, check)
    676         rawmode, mode = _OUTMODES[mode]
    677     except KeyError:
--> 678         raise IOError("cannot write mode %s as PNG" % mode)
    679 
    680     if check:

OSError: cannot write mode I;16 as PNG

arve0 on 5 Feb 2015

convert works without loosing data:

img = img.convert(mode='I')
img.save('16bit.png')

Is this the The Right Way To Do It™?

arve0 on 5 Feb 2015

I;16 is not a valid outmode for PNG, as you've found. I mode images are written as I;16B, which is a 16bit big endian PNG. (potentially losing information if you've actually got a 32 bit I image, but ... not important for this operation). Convert's your best bet.

The I;16 family is kind of a weird format, we support it for reading, but it's not really a fully supported format for all image operations where we'd support I.