fixImageOrientation.py

'''
fixImageOrientation.py

All credits go to Kyle Fox who wrote this EXIF orientation patch.
We just modified tiny pieces. https://github.com/kylefox

The code is free for non-commercial use.
Please contact the author for commercial use.

Please cite the DIRT Paper if you use the code for your scientific project.

Bucksch et al., 2014 "Image-based high-throughput field phenotyping of crop roots", Plant Physiology

-------------------------------------------------------------------------------------------
Author: Alexander Bucksch
School of Biology and Interactive computing
Georgia Institute of Technology

Mail: bucksch@gatech.edu
Web: http://www.bucksch.nl
-------------------------------------------------------------------------------------------

Copyright (c) 2014 Alexander Bucksch
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:

  * Redistributions of source code must retain the above copyright
    notice, this list of conditions and the following disclaimer.

  * Redistributions in binary form must reproduce the above
    copyright notice, this list of conditions and the following
    disclaimer in the documentation and/or other materials provided
    with the distribution.

  * Neither the name of the DIRT Developers nor the names of its
    contributors may be used to endorse or promote products derived
    from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

'''

from PIL import Image, ImageFile

__all__ = ['fix_orientation']

# PIL's Error "Suspension not allowed here" work around:
# s. http://mail.python.org/pipermail/image-sig/1999-August/000816.html
ImageFile.MAXBLOCK = 1024*1024

# The EXIF tag that holds orientation data.
EXIF_ORIENTATION_TAG = 274

# Obviously the only ones to process are 3, 6 and 8.
# All are documented here for thoroughness.
ORIENTATIONS = {
    1: ("Normal", 0),
    2: ("Mirrored left-to-right", 0),
    3: ("Rotated 180 degrees", 180),
    4: ("Mirrored top-to-bottom", 0),
    5: ("Mirrored along top-left diagonal", 0),
    6: ("Rotated 90 degrees", -90),
    7: ("Mirrored along top-right diagonal", 0),
    8: ("Rotated 270 degrees", -270)
}

def fix_orientation(img, save_over=False):
    """
    `img` can be an Image instance or a path to an image file.
    `save_over` indicates if the original image file should be replaced by the new image.
    * Note: `save_over` is only valid if `img` is a file path.
    """
    path = None
    if not isinstance(img, Image.Image):
        path = img
        img = Image.open(path)
    elif save_over:
        raise ValueError("You can't use `save_over` when passing an Image instance.  Use a file path instead.")
    try:
        orientation = img._getexif()[EXIF_ORIENTATION_TAG]
    except (TypeError, AttributeError, KeyError):
        print "WARNING: Image file has no EXIF data."
        orientation=-1
        pass
    if orientation in [3,6,8]:
        degrees = ORIENTATIONS[orientation][1]
        img = img.rotate(degrees)
        if save_over and path is not None:
            try:
                img.save(path, quality=100)
            except IOError:
                # Try again, without optimization (PIL can't optimize an image
                # larger than ImageFile.MAXBLOCK, which is 64k by default).
                # Setting ImageFile.MAXBLOCK should fix this....but who knows.
                img.save(path, quality=100)
        return (img, degrees)
    else:
        return (img, 0)