rpieki / PyQtImageViewer

PyQt image viewer widget with mouse zooming and panning.

PyQtImageViewer

• QtImageViewer: Yet another PyQt6 or PyQt5 image viewer widget. Comes prepackaged with several easily configurable options for display (aspect ratio, scroll bars) and mouse interaction (zoom, pan, click signals). Also has limited support for ROIs. Displays a QImage, QPixmap, or NumPy 2D array. To display any other image format, you must first convert it to one of the supported formats (e.g., see Pillow, ImageQt, and qimage2ndarray).
• QtImageStackViewer: Multi-page image stack viewer similar to ImageJ. Based off of QtImageViewer with sliders for traversing frames and/or channels and a titlebar that displays the current frame in the stack and mouse position coordinates like in ImageJ. Image stacks can either be specified directly as NumPy 3D arrays [rows, columns, frames] or multi-page image files can be read from file using Pillow. For image files, the data is loaded frame by frame as needed which avoids loading huge image stack files into memory and enables fast loading and scrolling through frames in the widget.

Author: Marcel Goldschen-Ohm
Email: [e-mail]
License: MIT
Copyright (c) 2022 Marcel Goldschen-Ohm

INSTALL

Everything's in QtImageViewer.py and QtImageStackViewer.py. Just put these somewhere where your project can find them.

Requirements:

• PyQt6 or PyQt5
• NumPy
• Pillow

QtImageViewer Basic Example

import sys
from PyQt6.QtCore import Qt
from PyQt6.QtWidgets import QApplication
from QtImageViewer import QtImageViewer


# Custom slot for handling mouse clicks in our viewer.
# This example just prints the (row, column) matrix index
# of the image pixel that was clicked on.
def handleLeftClick(x, y):
    row = int(y)
    column = int(x)
    print("Pixel (row="+str(row)+", column="+str(column)+")")
    

if __name__ == '__main__':
    # Create the QApplication.
    app = QApplication(sys.argv)
        
    # Create an image viewer widget.
    viewer = QtImageViewer()
        
    # Set viewer's aspect ratio mode.
    # !!! ONLY applies to full image view.
    # !!! Aspect ratio always ignored when zoomed.
    #   Qt.AspectRatioMode.IgnoreAspectRatio: Fit to viewport.
    #   Qt.AspectRatioMode.KeepAspectRatio: Fit in viewport using aspect ratio.
    #   Qt.AspectRatioMode.KeepAspectRatioByExpanding: Fill viewport using aspect ratio.
    viewer.aspectRatioMode = Qt.AspectRatioMode.KeepAspectRatio
    
    # Set the viewer's scroll bar behaviour.
    #   Qt.ScrollBarPolicy.ScrollBarAlwaysOff: Never show scroll bar.
    #   Qt.ScrollBarPolicy.ScrollBarAlwaysOn: Always show scroll bar.
    #   Qt.ScrollBarPolicy.ScrollBarAsNeeded: Show scroll bar only when zoomed.
    viewer.setHorizontalScrollBarPolicy(Qt.ScrollBarPolicy.ScrollBarAlwaysOff)
    viewer.setVerticalScrollBarPolicy(Qt.ScrollBarPolicy.ScrollBarAlwaysOff)
    
    # Allow zooming by draggin a zoom box with the left mouse button.
    # !!! This will still emit a leftMouseButtonReleased signal if no dragging occured,
    #     so you can still handle left mouse button clicks in this way.
    #     If you absolutely need to handle a left click upon press, then
    #     either disable region zooming or set it to the middle or right button.
    viewer.regionZoomButton = Qt.MouseButton.LeftButton  # set to None to disable
    
    # Pop end of zoom stack (double click clears zoom stack).
    viewer.zoomOutButton = Qt.MouseButton.RightButton  # set to None to disable
    
    # Mouse wheel zooming.
    viewer.wheelZoomFactor = 1.25  # Set to None or 1 to disable
    
    # Allow panning with the middle mouse button.
    viewer.panButton = Qt.MouseButton.MiddleButton  # set to None to disable
        
    # Load an image file to be displayed (will popup a file dialog).
    viewer.open()
    
    # Handle left mouse clicks with your own custom slot
    # handleLeftClick(x, y). (x, y) are image coordinates.
    # For (row, col) matrix indexing, row=y and col=x.
    # QtImageViewer also provides similar signals for
    # left/right mouse button press, release and doubleclick.
    # Here I bind the slot to leftMouseButtonReleased only because
    # the leftMouseButtonPressed signal will not be emitted due to
    # left clicks being handled by the regionZoomButton.
    viewer.leftMouseButtonReleased.connect(handleLeftClick)
        
    # Show the viewer and run the application.
    viewer.show()
    sys.exit(app.exec())

QtImageStackViewer Basic Example

import sys
from PyQt6.QtCore import Qt
from PyQt6.QtWidgets import QApplication
from QtImageStackViewer import QtImageStackViewer
    

if __name__ == '__main__':
    # Create the QApplication.
    app = QApplication(sys.argv)
        
    # Create an image stack viewer widget.
    viewer = QtImageStackViewer()
    
    # Customize mouse interaction via the QtImageViewer widget.
    viewer.imageViewer.regionZoomButton = Qt.MouseButton.LeftButton  # set to None to disable
    viewer.imageViewer.zoomOutButton = Qt.MouseButton.RightButton  # set to None to disable
    viewer.imageViewer.wheelZoomFactor = 1.25  # Set to None or 1 to disable
    viewer.imageViewer.panButton = Qt.MouseButton.MiddleButton  # set to None to disable
        
    # Load an image stack file to be displayed (will popup a file dialog).
    viewer.open()
        
    # Show the viewer and run the application.
    viewer.show()
    sys.exit(app.exec())