How to write PNG image to string with the PIL

Question

I have generated an image using PIL  How can I save it to a string in memory  The Image save   method requires a file   I d like to have several such images stored in dictionary

User · Answer

For Python3 it is required to use BytesIO:

from io import BytesIO
from PIL import Image, ImageDraw

image = Image.new("RGB", (300, 50))
draw = ImageDraw.Draw(image)
draw.text((0, 0), "This text is drawn on image")

byte_io = BytesIO()

image.save(byte_io, 'PNG')

Read more: http://fadeit.dk/blog/post/python3-flask-pil-in-memory-image

User · Answer

sth s solution didn t work for me because in         Imaging PIL Image pyc line 1423 -    raise KeyError ext    unknown   extension   It was trying to detect the format from the extension in the filename   which doesn t exist in StringIO case    You can bypass the format detection by setting the format yourself in a parameter    import StringIO output   StringIO StringIO   format    PNG    or  JPEG  or whatever you want image save output  format  contents   output getvalue   output close

User · Answer

When you say  I d like to have number of such images stored in dictionary   it s not clear if this is an in-memory structure or not   You don t need to do any of this to meek an image in memory   Just keep the image object in your dictionary   If you re going to write your dictionary to a file  you might want to look at  im tostring   method and the Image fromstring   function  http   effbot org imagingbook image htm     im tostring      string      Returns a string containing pixel   data  using the standard  raw    encoder       Image fromstring mode  size  data       image      Creates an image memory from pixel   data in a string  using the standard    raw  decoder    The  format    jpeg   png  etc   only matters on disk when you are exchanging the files   If you re not exchanging files  format doesn t matter

User · Answer

You can use the BytesIO class to get a wrapper around strings that behaves like a file  The BytesIO object provides the same interface as a file  but saves the contents just in memory   import io  with io BytesIO   as output      image save output  format  GIF       contents   output getvalue     You have to explicitly specify the output format with the format parameter  otherwise PIL will raise an error when trying to automatically detect it   If you loaded the image from a file it has a format parameter that contains the original file format  so in this case you can use format image format   In old Python 2 versions before introduction of the io module you would have used the StringIO module instead

User · Answer

With modern  as of mid-2017 Python 3 5 and Pillow 4 0    StringIO no longer seems to work as it used to  The BytesIO class is the proper way to handle this  Pillow s save function expects a string as the first argument  and surprisingly doesn t see StringIO as such  The following is similar to older StringIO solutions  but with BytesIO in its place   from io import BytesIO from PIL import Image  image   Image open  a file png   faux file   BytesIO   image save faux file   png

User · Answer

save   can take a file-like object as well as a path  so you can use an in-memory buffer like a StringIO   buf   StringIO StringIO   im save buf  format  JPEG   jpeg   buf getvalue

[python] How to write PNG image to string with the PIL?

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