I've also run into this issue. The problem is in
pyqtgraph/graphicsItems/ImageItem.py, in getHistogram():
if bins == 'auto':
mn = stepData.min()
mx = stepData.max()
...when mx == mn. I just added in immediately after that:
if mx == mn:
mx += 1
On Monday, February 19, 2018 at 4:43:37 AM UTC-5, Luca Piazza wrote:
>
> Hello everybody!
>
> beginner here... ;)
> I'm writing a little GUI in PYQT5 to display images and I'd like to add
> this histogram function.
> The problem arises when my images are almost or completely black.
> In case of an image with all 0 pixels the histogram breaks my application
> raising the following error:
>
> File "C:\Program
>> Files\Python36\lib\site-packages\pyqtgraph\graphicsItems\ImageItem.py",
>> line 464, in getHistogram
>> bins = np.arange(mn, mx+1.01*step, step, dtype=np.int)
>> ValueError: arange: cannot compute length
>
>
>
> In case of an image with very few counts the histogram breaks my
> application raising the following error:
>
> File "C:\Program
>> Files\Python36\lib\site-packages\numpy\lib\function_base.py", line 727, in
>> histogram
>> '`bins` must increase monotonically, when an array')
>> ValueError: `bins` must increase monotonically, when an array
>
>
> Any idea for any solutions?
> I don't have the knowledge, unfortunately, to modify the widget myself.
>
> Thanks!
> Luca
>
>
> ps... I will prepare a minimal example in few hours, but I preferred to
> post this first
>
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