Sort images by dimension, and check the images to delete.

dimensionsortzenity.sh

#!/bin/bash
#expecting 2 args:
#	function display or delete
#	a directory containing images

ZENITY_X=0
ZENITY_Y=0
ZENITY_W=500
ZENITY_H=400


#set options according to function in $1, if isn't recognised, exit
#MAX_INPUT is max number of files in list taken from sort by (width+height)
#MAX_OUTPUT is max number of files to display or delete
#SORTING is command line options for sort; data lines: w+h w h file
case $1 in
	display) MAX_OUTPUT=500; MAX_INPUT=500; SORTING="-n -r" ;;
	delete) MAX_OUTPUT=500; MAX_INPUT=500; SORTING="-n" ;;
	*)	exit ;;
esac

WIN_TITLE="ZenityImageSorter_$1"

#exit if $2 is null or can't enter directory $2
if [[ -z $2 ]] || ! cd "$2" 2>/dev/null; then exit; fi

function IDandSort {
	while
		read w h f
	do
		#skip file if identify didn't identify it
		if [[ $w ]] && [[ $h ]]; then
			printf "%05d %05d %05d %s\n" $((w+h)) $w $h "$f"
		fi
	done < <(identify -format "%w %h %f\n" *) | sort $SORTING | head -n $MAX_INPUT
}

function selectImages {
	#run a loop in background to resize/move window when it's up
	{ 	while 
			! wmctrl -l -G|grep "$WIN_TITLE" >/dev/null 
		do 
			sleep 0.05
		done
		wmctrl -r "$WIN_TITLE" -e 0,$ZENITY_X,$ZENITY_Y,$ZENITY_W,$ZENITY_H
	} &
	
	while
		read s w h file
	do
		printf "%s\n%s\n%s\n" $w $h "$file"
	done < <(IDandSort) | \
		zenity --list --multiple --title="$WIN_TITLE" --print-column=3 \
				--column "width" --column "height" --column="file name" 2>/dev/null | \
		tr "|" "\n"
}


readarray -n $MAX_OUTPUT -t images <<< "`selectImages`"

#end if no files returned
[[ -z ${images[0]} ]] && exit

#run command on each returned file
case $1 in
	display)
		for file in "${images[@]}"; do
			display "$file" &
		done ;;
	delete)
		rm -f "${images[@]}" ;;
esac

#don't exit till all child processes have finished
wait