After Importing the image on canvas do the following steps 1) Make sure you have selected the imported image layer in Layer Panel
2) Then go to the toolbox and select Scale Tool
3) Press ctrl-A, observe on canvas all handles (of image) will select (bright color of handle indication shows that the node (duck) are selected)
4) Go to any node press the mouse click button and drag to scaling the image
5) To increase size drag outward direction to decrease size drag inward direction on canvas