#!/bin/sh

# 16:9 screen resolution ratio
wratio=16
hratio=9
chopnum=99%

width=$(identify -format '%w' "$1")
height=$(identify -format '%h' "$1")

dim=$(echo "$width*100/$height" | bc)

if [ "$dim" -ne 177 ]; then
	if [ "$dim" -lt 177 ]; then
		chopgeom="${chopnum}x0"	
		width=$(echo "$height*$wratio/$hratio" | bc)
	else
		chopgeom="0x${chopnum}"	
		height=$(echo "$width*$hratio/$wratio" | bc)
	fi
	extgeom="${width}x${height}"
	bgcolor=$(convert "$1" -gravity center -chop "$chopgeom" -define histogram:unique-colors=true -format %c histogram:info:- | sort -rn | head -n1 | awk \{print\ \$3\} | cut -c1-7)
	convert "$1" -gravity center -background "$bgcolor" -extent "$extgeom" "$2"
else
	echo 'same resolution ratio, no need to convert' >&2
	exit 1
fi