fix unsupported exif jpeg image rotation

fix-jpeg-rotation.py

"""
some images get broken in desktop browsers because they're rotate with exif tags, which desktop browsers don't support, but ios does. 
(More specifically, neither desktop Chrome, Safari or Firefox on OSX as of 1/2/18 seem to respect exif tags when the image is embedded 
in a page, though at least Chrome respects them when the file is opened in its own tab.)
see: https://www.howtogeek.com/254830/why-your-photos-dont-always-appear-correctly-rotated/ + 
https://stackoverflow.com/questions/42401203/chrome-image-exif-orienation-issue

This leads to a weird situation where you can have a photo that was rotated in some exif-happy app that looks correct on ios but not 
on any desktop browser.  Let's fix this.

# this script takes a folder full of thus-broken images, strips the exif nonsense, and rotates each 90 degrees clockwise 
(which happens to be the problem I had.  change line 39 to use a different rotation and see the man page for jpegtran).  

This tiny script is the equivalent of (from commandline, for each file):

> exiv2 rm foo.jpg
> jpegtran -rotate 90 foo.jpg > temp-foo.jpg
> rm foo.jpg
> mv temp-foo.jpg foo.jpg

requires libjpeg (brew install jpeg) and exiv2 (brew install exiv2)
"""

from glob import glob
from os import rename, remove
from subprocess import call

tempfiles = []
filenames = glob("*.jpg")
for x in filenames:
    newname = "temp-" + x
    rename(x, newname)
    tempfiles.append(newname)

for x in tempfiles:
    command = ["exiv2", "rm", x]
    call(command)
    oldname = x[5:]
    secondcommand = ["jpegtran", "-rotate", "90", x]
    with open(oldname, "wb") as outfile:
        call(secondcommand, stdout=outfile)
    remove(x)

Truly hopeless Chrome issues where this has been a known problem since 2010: https://bugs.chromium.org/p/chromium/issues/detail?id=56845 https://bugs.chromium.org/p/chromium/issues/detail?id=158753

Favorite comment from the latter issue:

I also vote against the "image-orientation:from-image" property.
It would be like adding "buggy-behavior:false".