Google Chrome has a nice feature - it can create bold-italic letters on the fly from italic letters (in case a font has italic style but does not have bold-italic). The result looks good enough: letters become thicker only in vertical direction, thin horisontal lines are there. In comparison the same result from Firefox is awful.
Is there a way to do this automatically on the whole font in free font editor or any other free app (CLI is also OK)? May be Chrome uses some free engine...
Here is a screenshot of Linux Libertine in Chrome. Top example is a semibold-italic made by font author. Middle example is italic by author. At the bottom is an automatically generated by Chrome pseudo-semibold-italic from italic. In the red is a screenshot from FontForge after changing font weight.