If you want text and are okay with using something other than Preview, then the free version of PDF Expert described here is a good solution.Ī simple workaround to change the background color in Skim is to (ab)use the reading bar preferences: The above do not preserve text, but produce images. Converting the resulting images into a PDF is done with a very simple Automator action, shown below: The first ffmpeg command inverts the colors of the screen recording and the second ffmpeg command places images from the screen recording into a sub folder at the rate of 2 per second. jpg's in the sub folder, right click and choose the Automator action shown below to make a new PDF
Here's a workaround for a large number of pages, but it involves using ffmpeg and Automator repeat for each page then File>Export>PDF.
Here is a work around for those who want to use Preview:
