If a background image has been set using Terminal.BackgroundImage, Terminal.BackgroundImageFile, or Vte.Terminal.Background.Transparent, the terminal will adjust the brightness of the image before drawing the image. To do so, the terminal will create a copy of the background image (or snapshot of the root window) and modify its pixel values.

If your application intends to create multiple terminal widgets with the same settings, performing this step yourself and just using Terminal.BackgroundImage will save memory.