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 arp242.net/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:

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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 😅