As we have seen earlier, OpenCV treats images as NumPy arrays—typically, 3D arrays in BGR format or 2D arrays in grayscale format. Conversely, wxPython has its own classes for representing images, typically in RGB format (the reverse of BGR). These classes include wx.Image (an editable image), wx.Bitmap (a displayable image), and wx.StaticBitmap (a GUI element that displays a Bitmap).

Our wxUtils module will provide a function that converts a NumPy array from either BGR or grayscale to an RGB Bitmap, ready for display in a wxPython GUI. This functionality depends on OpenCV and wxPython, as reflected in the following import statements:

from CVBackwardCompat import cv2
import wx

Conveniently, wxPython provides a factory function called wx.BitmapFromBuffer(width, height, dataBuffer), which returns a new Bitmap. This function can accept a NumPy array in RGB format as the dataBuffer argument. However, a bug causes BitmapFromBuffer to fail on the first-generation...