Saving plot to tiff, with high resolution for publication (in R)

Question

A journal we are sending an article to is asking for the following:

To ensure the best reproduction quality of your figures we would appreciate high r

Answer 1

When you increase resolution (res), the effective size of a plot decreases, and so the margin error jumps out. Try to make bigger picture with greater width and height (in theory, to make a plot of a same virtual size, it should be new_(width|height)=res/72*old_(width|height).
Still, as romunov suggested, it is a better idea to use ImageMagick; you won't loose quality.