Stuck at ExportByteArray

session=WolframLanguageSession()
img = Image.open("path_to_image")
data = session.evaluate(wl.CurvatureFlowFilter(img, 50))
z = session.evaluate(wl.ExportByteArray(data, "PNG"))

Changing CurvatureFlowFilter to other functions like ‘Binarize’ gives the desired output but gets stuck at ExportByteArray.

This is the Trace when process is manually interrupted:

File “/home/nikhal/.PyCharmCE2019.1/config/scratches/scratch_82.py”, line 25, in Binarize z = session.evaluate(wl.ExportByteArray(data, “PNG”)) File “/usr/local/lib/python3.6/dist-packages/wolframclient/evaluation/kernel/localsession.py”, line 259, in evaluate result = self.evaluate_wrap(expr, **kwargs) File “/usr/local/lib/python3.6/dist-packages/wolframclient/evaluation/kernel/localsession.py”, line 256, in evaluate_wrap return self.evaluate_wrap_future(expr, **kwargs).result() File “/usr/lib/python3.6/concurrent/futures/_base.py”, line 427, in result self._condition.wait(timeout) File “/usr/lib/python3.6/threading.py”, line 295, in wait waiter.acquire() KeyboardInterrupt

Here is my code: binarize.txt

[DbxDev]

I suspect that the size of the input image makes a difference here.

I ran your script on a 100kb file (ExampleData[{"TestImage", "House"}]) and it worked. Then I used a bigger one generated with RandomImage[1, {2000, 2000}, ColorSpace -> "RGB"]. This time it took a lot of time to evaluate CurvatureFlowFilter. Log says ~80sec.

To better understand where the bottleneck is, I ran the code in a notebook. With an image of size 200x200 pixels, I already get an evaluation timer of a second:

In[1]:= img = RandomImage[1, {200, 200}, ColorSpace -> "RGB"];

In[2]:= AbsoluteTiming[CurvatureFlowFilter[img, 50];]
Out[2]= {1.14688, Null}

No doubt that it would takes tens of seconds for the bigger picture I mentioned above.

A quick comment, not related, in general one should avoid as much as possible to send data back and forth to the kernel. Remove unnecessary intermediate variables whenever you can.

e.g.: rewriting

    data = session.evaluate(wl.CurvatureFlowFilter(img, 50))
    z = session.evaluate(wl.ExportByteArray(data, "PNG"))

as

z = session.evaluate(
        wl.ExportByteArray(
            wl.CurvatureFlowFilter(img, 50), "PNG"
        ))

reduces the data exchanged to only the resulting byte array. Of course your code is much easier to debug and I understand why you would write it this way until it actually works, so feel free to ignore this.

[DbxDev]

Closing the issue.