How to check if a file is a valid image file

Question

I am currently using PIL   from PIL import Image try      im Image open filename        do stuff except IOError        filename not an image file   However  while this sufficiently covers most cases  some image files like  xcf  svg and psd are not being detected  Psd files throws an OverflowError exception   Is there someway I could include them as well

User · Answer

You could use the Python bindings to libmagic  python-magic and then check the mime types  This won t tell you if the files are corrupted or intact but it should be able to determine what type of image it is

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Update  I also implemented the following solution in my Python script here on GitHub   I also verified that damaged files  jpg  frequently are not  broken  images i e  a damaged picture file sometimes remains a legit picture file  the original image is lost or altered but you are still able to load it with no errors  But  file truncation cause always errors    End Update  You can use Python Pillow PIL  module  with most image formats  to check if a file is a valid and intact image file   In the case you aim at detecting also broken images   Nadia Alramli correctly suggests the im verify   method  but this does not detect all the possible image defects  e g   im verify does not detect truncated images  that most viewers often load with a greyed area    Pillow is able to detect these type of defects too  but you have to apply image manipulation or image decode recode in or to trigger the check  Finally I suggest to use this code   try    im   Image load filename    im verify    I perform also verify  don t know if he sees other types o defects   im close    reload is necessary in my case   im   Image load filename     im transpose PIL Image FLIP LEFT RIGHT    im close   except      manage excetions here   In case of image defects this code will raise an exception  Please consider that im verify is about 100 times faster than performing the image manipulation  and I think that flip is one of the cheaper transformations   With this code you are going to verify a set of images at about 10 MBytes sec with standard Pillow or 40 MBytes sec with Pillow-SIMD module  modern 2 5Ghz x86 64 CPU    For the other formats psd xcf    you can use Imagemagick wrapper Wand  the code is as follows   im   wand image Image filename filename  temp   im flip  im close     But  from my experiments Wand does not detect truncated images  I think it loads lacking parts as greyed area without prompting    I red that Imagemagick has an external command identify that could make the job  but I have not found a way to invoke that function programmatically and I have not tested this route   I suggest to always perform a preliminary check  check the filesize to not be zero  or very small   is a very cheap idea   statfile   os stat filename  filesize   statfile st size if filesize    0     manage here the  faulty image  case

User · Answer

A lot of times the first couple chars will be a magic number for various file formats   You could check for this in addition to your exception checking above

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I have just found the builtin imghdr module  From python documentation      The imghdr module determines the type   of image contained in a file or byte   stream    This is how it works    gt  gt  gt  import imghdr  gt  gt  gt  imghdr what   tmp bass    gif    Using a module is much better than reimplementing similar functionality

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In addition to what Brian is suggesting you could use PIL s verify method to check if the file is broken      im verify        Attempts to determine if the file is   broken  without actually decoding the   image data  If this method finds any   problems  it raises suitable   exceptions  This method only works on   a newly opened image  if the image has   already been loaded  the result is   undefined  Also  if you need to load   the image after using this method  you   must reopen the image file  Attributes

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Additionally to the PIL image check you can also add file name extension check like this   filename lower   endswith    png     jpg     jpeg     tiff     bmp     gif      Note that this only checks if the file name has a valid image extension  it does not actually open the image to see if it s a valid image  that s why you need to use additionally PIL or one of the libraries suggested in the other answers

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One option is to use the filetype package  Installation python -m pip install filetype Advantages  Quick  Does its work by loading the first few bytes of your image  check on the magic number  Supports different mime type  Images  Videos  Fonts  Audio  Archives   Example filetype  gt   1 0 7 import filetype  filename    quot  path to file jpg quot   if filetype is image filename       print f quot  filename  is a valid image    quot   elif filetype is video filename       print f quot  filename  is a valid video    quot    filetype  lt   1 0 6 import filetype  filename    quot  path to file jpg quot   if filetype image filename       print f quot  filename  is a valid image    quot   elif filetype video filename       print f quot  filename  is a valid video    quot    Additional information on the official repo  https   github com h2non filetype py

User · Answer

On Linux  you could use python-magic  http   pypi python org pypi python-magic 0 1  which uses libmagic to identify file formats   AFAIK  libmagic looks into the file and tries to tell you more about it than just the format  like bitmap dimensions  format version etc   So you might see this as a superficial test for  validity    For other definitions of  valid  you might have to write your own tests

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format      jpg    png    jpeg    for  path dirs files  in os walk path        for file in files           if file endswith tuple format                 print path               print   Valid  file           else               print path               print  InValid  file

[python] How to check if a file is a valid image file?

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