Enhanced Metafile (EMF) converter

EMF, the Enhanced Metafile, is Windows' vector picture format: a list of GDI drawing commands with a header that starts with record type 1 and the signature " EMF" at byte 40. Office adds EMF+ records on top for anti-aliasing, transparency and gradients. Charts copied out of Excel, diagrams exported from Visio, figures embedded in Word and PowerPoint files and many CAD and lab-instrument exports are EMF, which is why the files turn up wherever Windows output meets Mac, Linux or the web.

Our office engine plays the metafile commands and places the picture on a page, and we then trim that page to the drawing with a small margin. That gives a tight PDF figure, or a PNG, JPG or SVG of just the picture. Pictures wider than an A4 page are scaled down to fit before trimming, so ask for more pixels with width or dpi when a large chart has to stay detailed.

In our tests charts, clip-art and slide exports came out with their text, bars and gradients in place, including files written with EMF+. Text written in an old Windows code page rather than Unicode can come out as the wrong characters, as Hebrew chart labels did, and the background is always white. A file that draws nothing visible is refused instead of returning a blank image.