We were encountering some errors when saving specific JPEG images.
The error was shown in stderr as:
IOError: encoder error -2 when writing image file
And on stdout it printed:
Suspension not allowed here
The problem was the bufsize not contemplating the icc_profile block.
iter(dict) is equivalent to iter(dict.keys()), so simply act on the dict
instead of adding the extra call.
Inspired by Lennart Regebro's PyCon 2017 presentation "Prehistoric
Patterns in Python". Available at:
https://www.youtube.com/watch?v=V5-JH23Vk0I
* DPI is a tuple
* Some EXIF only contains an X resolution for DPI
* Refactor
* Test with no DPI in EXIF
* Handle EXIF with no DPI
* Created with: exiftool "-*resolution*"= photoshop-200dpi.jpg
* Test when not in EXIF, DPI==72,72
* Use X resolution for Y, default to 72,72 dpi
* Created with: exiftool -exif:ResolutionUnit=cm photoshop-200dpi.jpg
* Test for EXIF with dpcm instead of dpi
* Convert dpcm to dpi, and default to inches if unit unknown
When saving a JPEG and specifying 'keep' for quality or subsampling,
if the source JPEG image is in grayscale mode, don't try to find the
subsampling of the source, because grayscale images don't have any
subsampling (it's only for color components).
For the moment the fix also ignores subsampling of CMYK JPEG because
currently Pillow doesn't support encoding JPEG in YCCK mode (and
subsampling doesn't make sense in CMYK, but Pillow permits saving CMYK
JPEG with subsampling, that's a bug). This fix pass those errors
silently, i.e. it doesn't raise an error when 'keep' is used but it's
not possible to keep the subsampling (because the image is grayscale
or CMYK). I think it's the proper behavior but I'm not sure.
