# High variation in the signal displayed by MNE-Qt-Browser as one moves through the signal

**URL:** <https://mne.discourse.group/t/high-variation-in-the-signal-displayed-by-mne-qt-browser-as-one-moves-through-the-signal/8588>\
**Category:** Support & Discussions\
**Created:** [April 3, 2024, 9:25am UTC](https://mne.discourse.group/t/high-variation-in-the-signal-displayed-by-mne-qt-browser-as-one-moves-through-the-signal/8588 "2024-04-03T09:25:02Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![ealtamir](https://yyz2.discourse-cdn.com/free1/user_avatar/mne.discourse.group/ealtamir/32/2201_2.png) [@ealtamir](https://mne.discourse.group/u/ealtamir)\
**Post date:** [April 3, 2024, 9:25am UTC](https://mne.discourse.group/t/high-variation-in-the-signal-displayed-by-mne-qt-browser-as-one-moves-through-the-signal/8588/1 "2024-04-03T09:25:02Z")

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Hi Folks,

I’m writing to hear your thoughts about something we’ve noticed while using the Qt browser. The displayed signals change substantially when one scrolls just a few seconds through the signal. Here’s a brief GIF to show what I’m talking about.

Is this normal behavior? Is there any way the variation can be reduced?

![mne-qt-browser-behavior](https://global.discourse-cdn.com/free1/uploads/mne/original/2X/1/1cbb5cd6e92e9ea19e666e6a92f3403ce2785610.gif)

Many thanks!

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**Author:** ![mscheltienne](https://yyz2.discourse-cdn.com/free1/user_avatar/mne.discourse.group/mscheltienne/32/827_2.png) [@mscheltienne](https://mne.discourse.group/u/mscheltienne)\
**Post date:** [April 3, 2024, 11:33am UTC](https://mne.discourse.group/t/high-variation-in-the-signal-displayed-by-mne-qt-browser-as-one-moves-through-the-signal/8588/2 "2024-04-03T11:33:13Z")

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I don’t really see an issue here.  
You could crop the end of the recording where it looks like your EEG cap was unplugged from the amplifier creating a large discontinuity. I’m guessing this large discontinuity is affecting the filter you applied to your data.

If you do:

```python
from matplotlib import pyplot as plt

plt.plot(raw.times, raw.get_data(picks=0).squeeze())

```

You should see the same plot (for channel 0), (except if you applied visualisation filters with `raw.plot(lowpass=..., highpass=...)`).

EDIT: @ealtamir I now see your issue. Please share the version of the `qt-browser` and of `mne` used (use `mne.sys_info()`); I believe this issue was fixed already and you are running on outdated versions.

Mathieu

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**Author:** ![ealtamir](https://yyz2.discourse-cdn.com/free1/user_avatar/mne.discourse.group/ealtamir/32/2201_2.png) [@ealtamir](https://mne.discourse.group/u/ealtamir)\
**Post date:** [April 3, 2024, 1:54pm UTC](https://mne.discourse.group/t/high-variation-in-the-signal-displayed-by-mne-qt-browser-as-one-moves-through-the-signal/8588/3 "2024-04-03T13:54:35Z")

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Hi Mathieu,

Thanks for your reply. I’m using v0.6.0, I will try the latest version as per your recommendation. For reference, he’s the output of `mne.sys_info()`:

```python
Platform Windows-10-10.0.22631-SP0
Python 3.11.2 (tags/v3.11.2:878ead1, Feb 7 2023, 16:38:35) [MSC v.1934 64 bit (AMD64)]
Executable C:\Users\phonb\AppData\Local\pypoetry\Cache\virtualenvs\pipeline-gui-3-Rle7Yj-py3.11\Scripts\python.exe
CPU Intel64 Family 6 Model 151 Stepping 2, GenuineIntel (24 cores)
Memory 31.7 GB
Core
├ mne 1.6.0 (outdated, release 1.6.1 is available!)
├ numpy 1.26.3 (OpenBLAS 0.3.23.dev with 24 threads)
├ scipy 1.11.4
├ matplotlib 3.8.2 (backend=QtAgg)
├ pooch 1.8.0
└ jinja2 3.1.2
Numerical (optional)
├ sklearn 1.3.2
└☐ unavailable numba, nibabel, nilearn, dipy, openmeeg, cupy, pandas
Visualization (optional)
├ qtpy 2.4.1 (PySide6=6.4.2)
├ pyqtgraph 0.13.3
├ mne-qt-browser 0.6.0
└☐ unavailable pyvista, pyvistaqt, vtk, ipympl, ipywidgets, trame_client, trame_server, trame_vtk, trame_vuetify

```

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<div class="post-metadata">

**Author:** ![mscheltienne](https://yyz2.discourse-cdn.com/free1/user_avatar/mne.discourse.group/mscheltienne/32/827_2.png) [@mscheltienne](https://mne.discourse.group/u/mscheltienne)\
**Post date:** [April 3, 2024, 2:23pm UTC](https://mne.discourse.group/t/high-variation-in-the-signal-displayed-by-mne-qt-browser-as-one-moves-through-the-signal/8588/4 "2024-04-03T14:23:12Z")

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This version should be recent enough… we might have a bug on our hands. Could you also try:

```python
raw.plot(precompute=False)
# vs
raw.plot(precompute=True)

```

Mathieu

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**Author:** ![cbrnr](https://yyz2.discourse-cdn.com/free1/user_avatar/mne.discourse.group/cbrnr/32/1409_2.png) [@cbrnr](https://mne.discourse.group/u/cbrnr)\
**Post date:** [April 4, 2024, 4:43am UTC](https://mne.discourse.group/t/high-variation-in-the-signal-displayed-by-mne-qt-browser-as-one-moves-through-the-signal/8588/5 "2024-04-04T04:43:20Z")

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I don’t understand what the problem is from the movie, can you explain?

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<div class="post-metadata">

**Author:** ![mscheltienne](https://yyz2.discourse-cdn.com/free1/user_avatar/mne.discourse.group/mscheltienne/32/827_2.png) [@mscheltienne](https://mne.discourse.group/u/mscheltienne)\
**Post date:** [April 4, 2024, 6:22am UTC](https://mne.discourse.group/t/high-variation-in-the-signal-displayed-by-mne-qt-browser-as-one-moves-through-the-signal/8588/6 "2024-04-04T06:22:23Z")

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@cbrnr Look at the left side (white background), after an horizontal scroll, the traces change completely. It kind of reminded me of a bug with projectors being toggle on/off during horizontal scrolls.