File > Options > Graphics > Other Graphics Options
Specify settings for automatic updating, gamma correction, and GDI for graphs. The changes you make to the defaults remain until you change them again, even after you exit Minitab.
Save Graph
Graph Resolution (dots per inch)
Specify the default graph resolution when you save a graph:
Automatic: Save graphs at the resolution specified by your monitor settings.
Custom: Save graphs at the resolution you specify. Enter a resolution between 50 and 1000.
