Python Forum

Hello,

I have a matplotlib figure that I want to return as a base64Encoded variable so it can be stored as a blob object. This variable would be the return result of a REST service so saving it directly to disk does not fit the project requirements.

I've tried various methods, but I cannot quite get the base64Encoded approach to work.

After the matplotlib is done, the following does create a disk file correctly:

[b]plt.savefig[/b]('test_file_spectrogram.png')

Now, to return that same figure as a base64Encoded variable, I tried this:

my_stringIObytes = io.BytesIO()
plt.savefig(my_stringIObytes, format='png')
my_stringIObytes.seek(0)
my_base64_jpgData = base64.b64encode(my_stringIObytes.read())

But when I convert this back to base64.decode(), it does not display a file. In fact, the actual png above is about 100KB, but this version when converted back is only 4KB.

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I also tried to just write the data from the above directly to disk without an intermediate program:

with open('base64_decode_test.png', 'wb') as fl:
    fl.write(my_stringIObytes.getbuffer())
    fl.close()

But that doesn't work correctly either.

Would appreciate some suggestions.

Thanks!

Oliver