ImageMagick is a set of command-line tools and libraries for manipulating and transforming images in succinct and powerful ways. One of the more useful possibilities is using ImageMagick to add logos in batch to all your site's article graphics and images.

I wrote this script to do just that. It looks for all *.png files recursively in the directory that you run it from. For each such file, it adds the specified label and puts it in a shaded box in the lower-right corner of the picture, like so:

The resulting files are placed in a results/ directory, which has a subtree structure that mirrors that of your original directory. The files are identically named, but now have the additional watermark attached to them.

The code is below for your viewing pleasure, and can be copy-pasted directly into any bash shell. Please feel free to make suggestions for improvement.

# ImageMagick image watermarker. (c) John Feminella (http://distilledb.com). You        \
#   may freely distribute this software and modify it, as long as you leave this        \
#   notice intact.                                                                      \
                                                                                        \
fontToUse="-font Droid-Sans-Mono-Regular -pointsize 10" ;                               \
labelToUse="distilledb.com" ;                                                           \
height=`convert ${fontToUse}                                                            \
  label:${labelToUse} -trim +repage -border 1 -format "%h" info:` ;                     \
offset=5;                                                                               \
for img in `find . -name "*.png" -type f -printf "%h/%f\n" | sed 's/^..//'`; do         \
  echo -n $img ;                                                                        \
  resultPath="results/$(dirname $img)/" ;                                               \
  resultFile="$(basename $img)" ;                                                       \
  result=$resultPath$resultFile ;                                                       \
  mkdir -p $resultPath ;                                                                \
  convert "$img"                                                                        \
    -gravity Southeast -background none -splice 0x$((${offset} + ${height} * 2))        \
    ${fontToUse}                                                                        \
    -undercolor '#00002008'                                                             \
    -stroke '#000C' -strokewidth 2 -annotate +${offset}+${offset} " ${labelToUse} "     \
    -stroke none    -fill white    -annotate +${offset}+${offset} " ${labelToUse} "     \
    -depth 8 "$result" ;                                                                \
  echo -e "\rcompleted: $result" ;                                                      \
done

Enjoy!