Cracks rudimentary CAPTCHA. Requires tesseract.

decaptcha.sh

#!/bin/sh
# decaptcha.sh - Cracks rudimentary CAPTCHA. Requires tesseract.
# ---

image="$1"
output=`mktemp`
charset="ABCDEFGHIJKLMNOPQRSTUVWXYZ"

command -v tesseract >/dev/null 2>&1 || { echo "Tesseract is not installed - (apt-get install tesseract-ocr) -  Aborting." >&2; exit 1; }

if [ -z $image ]; then
  echo "Usage: ./decaptcha.sh <FILE>"
  exit 1
fi

echo "(*) Processing $image..."
echo "tessedit_char_whitelist $charset" | tesseract "$image" "$output" -psm 7 /dev/stdin > /dev/null && cat "$output.txt" && rm "$output.txt"
rm "$output"