iOS 9.3 is coming in the Spring and will introduce Night Shift as well as a number of other new features.
A Look at Leopard's Preview 4.0
Beyond the basic PDF and image file viewing, Preview 4.0 adds new tools to annotate PDFs with ovals, rectangle, text notes and hyperlinks. (Oval and text annotation are available in the current version of Preview) Apple also added underline, strikeout, or highlight a text selection in the Acrobat compatible format. These additional tools, however, are not available in the default Preview toolbar. Users must customize the toolbar to have access to the new tools.
Image editing tools are also provided, including image correction, size adjustment, instant alpha, and extract shape, giving Preview an interesting subset of editing tools.
Preview 4.0 will ship with Mac OS X 10.5 Leopard which is expected to be released later this month.