imagemagick
montage -geometry +0+0 -tile 10x1 -background "#999999" -bordercolor "#ffffff" -border 2 -quality 95 * output.png
http://www.imagemagick.org/Usage/quantize/
montage -geometry +0+0 -tile 10x1 -background "#999999" -bordercolor "#ffffff" -border 2 -quality 95 * output.png
http://www.imagemagick.org/Usage/quantize/