Convert all images in directory to pdf file and produce compressed pdf file using ghostscript. Most suitable for image compression without loosing much of information.

images2pdf.sh

#!/bin/bash

#title           :images2pdf.sh
#description     :Best image compression ever.
#author		 :Pritesh Gohil
#date            :08 Jan 2021
#version         :0.1    
#usage		 :bash images2pdf.sh -i ../Desktop/img_dir/
#notes           :Install ImageMagick and ghostscript packages.
#bash_version    :5.0.16(1)-release
#==============================================================================

HELP="
Convert images in the src_dir to low resolution pdf files using ImageMagick and GhostScript

	[-h] 				Help
	[-i <image_directory>] 		Image directory
	[-o <save_directory>]		Path to save results (TO DO: NOT IMPLEMENTED)
	[-c]				Compress original pdf (TO DO: NOT IMPLEMENTED)
"

# Get arguments
options="i:o:h?"
while getopts $options opt; do
    case "$opt" in
    h)
        echo "$HELP"
        exit 0
        ;;
    i)  src_dir=$OPTARG
        ;;
    o)  out_dir=$OPTARG
        ;;
    esac
done

# Check atleast one argument given
if ((OPTIND==1))
then
	echo "Please provide input source directory. Use -i <src_dir>"
	exit 0
fi

echo Arguments: $@


if [ -z $src_dir ] 			#If -i args not provided
then
	echo "No such source directory"
	exit 0
else
	if [ ! -d "$src_dir" ]; 	#if directory doesn't exist
	then
		echo "invalid directory!!!"
		exit 0
	fi
	echo "reading images"
#	find "$src_dir" -type f -regex ".*\.\(png\|jpg\|jpeg\)" -print0 | while IFS= read -r -d $'\0' in_file
#	for file in "$src_dir"*.{jpg,jpeg,png} ;
	for file in $(ls $src_dir*.jpg $src_dir*.jpeg $src_dir*.png);
do
	echo "converting file $file"
	IMG=${file%.*}".pdf" 			#Remove file extension
	convert "$file" "$IMG.pdf"		#Intentinal double extension

	# Reduce pdf size using ghostscript
	echo "Compressing pdf"
	gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.5 -dNOPAUSE -dQUIET -dBATCH -dPrinted=false -sOutputFile=$IMG $IMG".pdf"

	# Remove double extension extra files
	rm $IMG".pdf"
done
fi

echo "finished conversion"