gistfile1.sh

#!/bin/sh
# 
# Identifies the predominant color in an image.
# You can specify certain colors to discard from the result.
#
# Usage: $0 <image> [colors to discard]

[ -z "$1" ] && exit 1

file="$1"
shift

COLORS="$@"

filter_colors() {
	while read color; do
		out=false
		for c in $COLORS; do
			echo "$color" | grep -q "$c" && out=true && break
		done
		$out && continue || echo "$color"
	done
}

identify -verbose "$file" | awk \
'BEGIN { parse=0 }
/^  Histogram:/ { parse=1; next }
/^ +[0-9]+:/ {
  if (parse == 1) {
    print gensub(/[ ]+([0-9]+):.+(#[A-F0-9]+).+/, "\\1 \\2", 1)
  }
}' | sort -n -r | filter_colors | head -1 | awk '{print $2}'