Insanely slow updating of pyqtgraph when changing colorbar bounds

kgenbio

I am having trouble with a pyqtgraph w/ colorbar updating very slowly. I have created an app in PyQt5 that takes a bunch of images, does some math, and then displays the image in a pyqtgraph ImageView() w/ a colorbar.

When I change the colorbar bounds, it takes about 5-6 seconds to actually move the colorbar widget to where I dragged it to, then another 5-6 seconds to update the image.

Here is the code I use to display the image. I call "display_plot" from a pyqtSlot inside the UI thread, no issues with it freezing/shutting down, the UI thread should be handling the image display.


import pyqtgraph as pg
from PyQt5 import QtWidgets

class ImageWindow(QtWidgets.QWidget):

    def __init__(self):
        self.graph_widget = pg.ImageView()
        self.cmap = pg.colormap.get('CET-L9')
        vbox = QtWidgets.QVBoxLayout(self)
        vbox.addWidget(self.graph_widget)

    def display_plot(self, image):
        self.graph_widget.setImage(image)
        self.graph_widget.setColorMap(self.cmap)

The image is a 3200x3200 grayscale np-image.

Is there someway I can make this ImageView() update faster? Anything I'm doing very wrong?

Also, when you set the colorbar/image, does it create a thread that will handle updating the image? who updates the image in this?

ChrisW67

@kgenbio You'd have to ask the PyQtGraph project how their processing works internally. I assume that the "colorbar widget" is part of the ImageView.

I have not used the library, but it looks to me that setColorMap() needs on be called once at ImageView setup. If you do that does it make a difference?

kgenbio

@ChrisW67 good point on setting it once. I posted on the pyqtgraph google group, thanks for the suggestion!