border is a simple commandline tool to add a border around PNG images.
When posting screenshots it's often useful to add a little border around the edges so it's easier to see where the screenshot ends. This tool does exactly that.
Install with go get zgo.at/border, which will put the binary in
~/go/bin/border.
Use -border to control the border width (default: 2) and -color to control
the colour (default: #999). The result is written to the original filename with
the value of -write inserted before the extension default: _border). Use
-write '' to overwrite the original.
Note: images are always saved as RGBA; you'll have to manually regenerate the palette if the input was indexed or greyscale.
Example:
Alternatively, you can use ImageMagick:
$ convert -border 2x2 -bordercolor '#999999' example.png example_border.png
ImageMagick can actually do much more. I'm just the kind of guy who likes to write his own simple tools 😅