Annotate non-PDF (raster) images in Preview

As is known, one can annotate PDF documents by means of Mac OS X standard Preview application. It turns out that the same functionality is available for raster images also, but for some reason, it's hidden by developers.  Open your picture in Preview, then select View » Customize Toolbar. Drag the Annotate tool to your toolbar.  Then just choose the type of annotation you want to make from the newly-created toolbar element, and use the mouse to add it to your picture. You can also use following modifiers:  Press the '+' or '-' keys to increase or decrease line thickness. Choose Tools » Show Colors and use the color wheel to change the color of the selected object (including notes). Choose Tools » Show Fonts and use the fonts panel to change the text note font. This functionality could be useful when commenting screenshots.