The image sample demonstrates use of the wxImage class and shows how to download images in a variety of formats, currently PNG, GIF, TIFF, JPEG, BMP, PNM and PCX. The top of the sample shows two rectangles, one of which is drawn directly in the window, the other one is drawn into a wxBitmap, converted to a wxImage, saved as a PNG image and then reloaded from the PNG file again so that conversions between wxImage and wxBitmap as well as loading and saving PNG files are tested.
At the bottom of the main frame there is a test for using a monochrome bitmap by drawing into a wxMemoryDC. The bitmap is then drawn specifying the foreground and background colours with wxDC::SetTextForeground and wxDC::SetTextBackground (on the left). The bitmap is then converted to a wxImage and the foreground colour (black) is replaced with red using wxImage::Replace.