# The context

Consider the following Emacs configuration

```
$ cat ~/.emacs.d/init.el
(org-babel-do-load-languages 'org-babel-load-languages
 '((python . t))
$
```

and the following Org mode file


```
$ cat ~/Experiments/main.org
#+begin_src python :tangle main.py :results file :file 1.png
from matplotlib import pyplot
x = [1, 2, 3]
y = [1, 4, 9]

pyplot.plot(x, y)
pyplot.savefig('1.png')
#+end_src
$
```

If I tangle the Python code block (i.e. execute `org-babel-tangle`), execute the Python script (i.e. execute `python main.py` in a shell) and obtain the hash of the resulting image I get

```
$ pwd
/home/myusername/Experiments
$ python main.py
$ sha512sum 1.png && du -h 1.png
084ffd63ec53665c21fc3eaba5f5ec3622d4d27a97f89cb67e3b436ca8093467272bbc239fd0e60dde27f5207ee33392f5b83b9eca1427efe7523450d92a6a8c 1.png
20K 1.png
```

I can open `1.png` with `firefox` and `mpv` without any problems.

If I execute the code block in Emacs by pressing `C-c C-c` (i.e. execute `org-babel-execute-src-block`) while the cursor is in the `#+BEGIN_SRC` block, I get the following

```
$ sha512sum 1.png && du -h 1.png
e39d05b72f25767869d44391919434896bb055772d7969f74472032b03bc18418911f3b0e6dd47ff8f3b2323728225286c3cb36914d28dc7db40bdd786159c0a 1.png
4.0K 1.png
```

Note that the size of `1.png` is significantly lower than the size shown above.

# Additional context

In addition to that, if I try to open the image with `mpv`, I get the following error

```
$ mpv 1.png
 (+) Video --vid=1 (png 1.000fps)
[ffmpeg/video] png: Invalid PNG signature 0x00000000.
Error while decoding frame!
(Paused) V: 00:00:01 / 00:00:01 (100%)
[ffmpeg/video] png: Invalid PNG signature 0x00000000.
Error while decoding frame!
(Paused) V: 00:00:01 / 00:00:01 (100%)
```

An error is also shown when I try to open the image in `firefox` (see image below)

[![enter image description here][1]][1]

The error is not present in both `firefox` and `mpv` when producing the image `1.png` by executing the script in a shell.

# The question

+ Why is the file `1.png` obtained after executing `org-babel-execute-src-block` different than the one produced by tangling the `#+BEGIN_SRC` block and executing `python main.py` in a shell?
+ Why does the resulting file `1.png` contain errors?

 [1]: https://i.sstatic.net/Il8wl.png