How to obtain image size using standard Python class without using external library

Question

I am using Python 2 5  And using the standard classes from Python  I want to determine the image size of a file   I ve heard PIL  Python Image Library   but it requires installation to work   How might I obtain an image s size without using any external library  just using Python 2 5 s own modules   Note I want to support common image formats  particularly JPG and PNG

User · Answer

Stumbled upon this one but you can get it by using the following as long as you import numpy.

import numpy as np

[y, x] = np.shape(img[:,:,0])

It works because you ignore all but one color and then the image is just 2D so shape tells you how bid it is. Still kinda new to Python but seems like a simple way to do it.

User · Answer

While it s possible to call open filename   rb   and check through the binary image headers for the dimensions  it seems much more useful to install PIL and spend your time writing great new software  You gain greater file format support and the reliability that comes from widespread usage  From the PIL documentation  it appears that the code you would need to complete your task would be   from PIL import Image im   Image open  filename png   print  width   d - height   d    im size   returns  width  height  tuple   As for writing code yourself  I m not aware of a module in the Python standard library that will do what you want  You ll have to open   the image in binary mode and start decoding it yourself  You can read about the formats at    PNG file format documentation Notes on the JPEG file format headers

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If you happen to have ImageMagick installed  then you can use  identify   For example  you can call it like this   path      folder image jpg  dim   subprocess Popen   identify   -format      w  h    path   stdout subprocess PIPE  communicate   0   width  height      int x  for x in re sub    t r n         dim  split

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Regarding Fred the Fantastic s answer   Not every JPEG marker between C0-CF are SOF markers  I excluded DHT  C4   DNL  C8  and DAC  CC   Note that I haven t looked into whether it is even possible to parse any frames other than C0 and C2 in this manner  However  the other ones seem to be fairly rare  I personally haven t encountered any other than C0 and C2    Either way  this solves the problem mentioned in comments by Malandy with Bangles jpg  DHT erroneously parsed as SOF    The other problem mentioned with 1431588037-WgsI3vK jpg is due to imghdr only being able detect the APP0  EXIF  and APP1  JFIF  headers   This can be fixed by adding a more lax test to imghdr  e g  simply FFD8 or maybe FFD8FF   or something much more complex  possibly even data validation   With a more complex approach I ve only found issues with  APP14  FFEE   Adobe   the first marker being DQT  FFDB   and APP2 and issues with embedded ICC PROFILEs   Revised code below  also altered the call to imghdr what   slightly   import struct import imghdr  def test jpeg h  f         SOI APP2   ICC PROFILE     if h 0 4       xff xd8 xff xe2  and h 6 17     b ICC PROFILE           print  A          return  jpeg        SOI APP14   Adobe     if h 0 4       xff xd8 xff xee  and h 6 11     b Adobe           return  jpeg        SOI DQT     if h 0 4       xff xd8 xff xdb           return  jpeg  imghdr tests append test jpeg   def get image size fname          Determine the image type of fhandle and return its size      from draco        with open fname   rb   as fhandle          head   fhandle read 24          if len head     24              return         what   imghdr what None  head          if what     png               check   struct unpack   gt i   head 4 8   0              if check    0x0d0a1a0a                  return             width  height   struct unpack   gt ii   head 16 24           elif what     gif               width  height   struct unpack   lt HH   head 6 10           elif what     jpeg               try                  fhandle seek 0    Read 0xff next                 size   2                 ftype   0                 while not 0xc0  lt   ftype  lt   0xcf or ftype in  0xc4  0xc8  0xcc                       fhandle seek size  1                      byte   fhandle read 1                      while ord byte     0xff                          byte   fhandle read 1                      ftype   ord byte                      size   struct unpack   gt H   fhandle read 2   0  - 2                   We are at a SOFn block                 fhandle seek 1  1     Skip  precision  byte                  height  width   struct unpack   gt HH   fhandle read 4               except Exception   IGNORE W0703                 return         else              return         return width  height   Note  Created a full answer instead of a comment  since I m not yet allowed to

User · Answer

Kurts answer needed to be slightly modified to work for me   First  on ubuntu  sudo apt-get install python-imaging  Then   from PIL import Image im Image open filepath  im size    width height  tuple   Check out the handbook for more info

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It depends on the output of file which I am not sure is standardized on all systems  Some JPEGs don t report the image size  import subprocess  re image size   list map int  re findall    d  x  d     subprocess getoutput  file    filename   -1

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Here s a python 3 script that returns a tuple containing an image height and width for  png   gif and  jpeg without using any external libraries  ie what Kurt McKee referenced above   Should be relatively easy to transfer it to Python 2   import struct import imghdr  def get image size fname          Determine the image type of fhandle and return its size      from draco        with open fname   rb   as fhandle          head   fhandle read 24          if len head     24              return         if imghdr what fname      png               check   struct unpack   gt i   head 4 8   0              if check    0x0d0a1a0a                  return             width  height   struct unpack   gt ii   head 16 24           elif imghdr what fname      gif               width  height   struct unpack   lt HH   head 6 10           elif imghdr what fname      jpeg               try                  fhandle seek 0    Read 0xff next                 size   2                 ftype   0                 while not 0xc0  lt   ftype  lt   0xcf                      fhandle seek size  1                      byte   fhandle read 1                      while ord byte     0xff                          byte   fhandle read 1                      ftype   ord byte                      size   struct unpack   gt H   fhandle read 2   0  - 2                   We are at a SOFn block                 fhandle seek 1  1     Skip  precision  byte                  height  width   struct unpack   gt HH   fhandle read 4               except Exception   IGNORE W0703                 return         else              return         return width  height

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That code does accomplish 2 things    Getting the image dimension Find the real EOF of a jpg file   Well when googling I was more interest in the later one   The task was to cut out a jpg file from a datastream  Since I I didn t find any way to use Pythons  image  to a way to get the EOF of so jpg-File I made up this   Interesting things  changes notes in this sample    extending the normal Python file class with the method uInt16  making source code better readable and maintainable   Messing around with struct unpack   quickly makes code to look ugly Replaced read over uninteresting  areas chunk with seek Incase you just like to get the dimensions you may remove the line   hasChunk   ord byte  not in range  0xD0  0xDA     0x00     - since that only get s important when reading over the image data chunk and comment in   break   to stop reading as soon as the dimension were found     but smile what I m telling - you re the Coder        import struct   import io os    class myFile file          def byte  self               return file read  self   1          def uInt16  self               tmp   file read  self   2             return struct unpack    gt H   tmp   0      jpeg   myFile  grafx ui s00   08521678 Unknown jpg    rb      try        height   -1       width    -1       EOI      -1        type check   jpeg read 2        if type check    b  xff xd8           print  Not a JPG          else           byte   jpeg byte            while byte    b               while byte    b  xff   byte   jpeg byte             while byte    b  xff   byte   jpeg byte                 FF D8       SOI Start of Image             FF D0  7  RST DRI Define Restart Interval inside CompressedData             FF 00           Masked FF inside CompressedData             FF D9       EOI End of Image             http   en wikipedia org wiki JPEG Syntax and structure           hasChunk   ord byte  not in range  0xD0  0xDA     0x00            if hasChunk                 ChunkSize      jpeg uInt16    - 2                ChunkOffset    jpeg tell                  Next ChunkOffset   ChunkOffset   ChunkSize               Find bytes  xFF  xC0  C3 That marks the Start of Frame           if  byte  gt   b  xC0  and byte  lt   b  xC3                   Found  SOF1  3 data chunk - Read it and quit             jpeg seek 1  os SEEK CUR              h   jpeg uInt16               w   jpeg uInt16                  break             elif  byte    b  xD9                     Found End of Image                EOI   jpeg tell                  break           else                  Seek to next data chunk              print  Pos    4x  x     jpeg tell    ChunkSize             if hasChunk                      jpeg seek Next ChunkOffset             byte   jpeg byte            width    int w          height   int h           print  Width   s  Height   s  JpgFileDataSize   x     width  height  EOI     finally        jpeg close

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Here s a way to get dimensions of a png file without needing a third-party module  From http   coreygoldberg blogspot com 2013 01 python-verify-png-file-and-get-image html  import struct  def get image info data       if is png data           w  h   struct unpack   gt LL   data 16 24           width   int w          height   int h      else          raise Exception  not a png image       return width  height  def is png data       return  data  8       211PNG r n 032 n and  data 12 16      IHDR     if   name         main         with open  foo png    rb   as f          data   f read        print is png data      print get image info data    When you run this  it will return   True  x  y    And another example that includes handling of JPEGs as well  http   markasread net post 17551554979 get-image-size-info-using-pure-python-code

User · Answer

Found a nice solution in another Stackoverflow post  using only standard libraries   dealing with jpg as well   JohnTESlade answer   And another solution  the quick way  for those who can afford running  file  command within python  run   import os info   os popen  file foo jpg   read   print info   Output   foo jpg  JPEG image data   density 28x28  segment length 16  baseline  precision 8  352x198  frames 3   All you gotta do now is to format the output to capture the dimensions  352x198 in my case

[python] How to obtain image size using standard Python class (without using external library)?

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