Experimental Physics and
Industrial Control System

"J. Lewis Muir" <[email protected]> · Tue, 20 Mar 2012 11:47:34 -0500

On 3/20/12 11:25 AM, J. Lewis Muir wrote:
> So it seems to be unhappy about the pixel mode.

Looking further, there's a debug level variable in PIL which
sheds more light on things:

===
>>> import PIL.Image
>>> PIL.Image.DEBUG = 1
>>> im = PIL.Image.open("/tmp/im.tif")
tag: ImageWidth (256) - type: short (3) - value: (1023,)
tag: ImageLength (257) - type: short (3) - value: (1023,)
tag: BitsPerSample (258) - type: short (3) - value: (32,)
tag: Compression (259) - type: short (3) - value: (1,)
tag: PhotometricInterpretation (262) - type: short (3) - value: (1,)
tag: Make (271) - type: ascii (2) - value: Unknown
tag: Model (272) - type: ascii (2) - value: Unknown
tag: StripOffsets (273) - type: long (4) - value: (8,)
tag: SamplesPerPixel (277) - type: short (3) - value: (1,)
tag: RowsPerStrip (278) - type: short (3) - value: (1023,)
tag: StripByteCounts (279) - type: long (4) - value: (4186116,)
tag: PlanarConfiguration (284) - type: short (3) - value: (1,)
*** Summary ***
- compression: raw
- photometric_interpretation: 1
- planar_configuration: 1
- fill_order: 1
- size: (1023, 1023)
format key: ('II', 1, 1, 1, (32,), ())
- unsupported format
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File
"/opt3/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/PIL/Image.py",
line 1980, in open
    raise IOError("cannot identify image file")
IOError: cannot identify image file
===

Looking at TiffImagePlugin.py where it generates the "-
unsupported format" message, and comparing the output with an
SLS PILATUS image that works, I see the following difference:

=== /tmp/im.tif (bad) ===
format key: ('II', 1, 1, 1, (32,), ())
===

=== /tmp/sls-im.tif (good) ===
format key: ('II', 1, 2, 1, (32,), ())
===

The third format key value is different.  Looking at
TiffImagePlugin.py shows that the third value is the value of
the SAMPLEFORMAT (339) tag.  In the bad TIFF, that tag appears
to be missing, but in the good TIFF, it's present and the debug
output shows it:

=== /tmp/sls-im.tif (good) ===
tag: SampleFormat (339) - type: short (3) - value: (2,)
===

Lewis

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System