Is there a zoom function on Smath?
1. Extend graph: by handles
2. X direction: Shift+mouse
3. Y direction: Ctrl+mouse
4. shift plot: click-in graph ... drag
5. An image from source [BW, RGB] paste in IrfanView,
from there => rotate/sharpen/resize-resample
once done in IrfanView => copy/paste in Smath.
Once in Smath don't touch to avoid destroying.