pdfcleanse

#!/usr/bin/env bash

# pdfcleanse 2025.03.12
# By Ricky Cheung <[email protected]>

# Variables:
# - COMPRESS_TYPE: bw, posterize, jpeg, webp
# - COMPRESS_BW_BRIGHTNESS (int - default: 15X1)
# - COMPRESS_POSTERIZE_LEVEL (int - default: 2)
# - EXTRACT_METHOD: ppm, images, magick (default: ppm)
# - SAVE_METHOD: gs, qpdf (default: gs)
# - REMOVE_WATERMARK (boolean - default: false)
# - ROTATION (int - default: 0)
# - DRY_RUN (boolean - default: false)
COMPRESS_BW_BRIGHTNESS=${COMPRESS_BW_BRIGHTNESS:=15X1}
COMPRESS_POSTERIZE_LEVEL=${COMPRESS_POSTERIZE_LEVEL:=2}
EXTRACT_METHOD=${EXTRACT_METHOD:=ppm}
SAVE_METHOD=${SAVE_METHOD:=gs}

WORK_DIR="/tmp/pdfcleanse"
WORK_FILE="$WORK_DIR/temp.pdf"

[[ -z "$@" ]] && echo "Usage: pdfcleanse input.pdf" && exit

compress_pdf() {
    if [[ "$COMPRESS_TYPE" == "bw" ]]; then
        magick $WORK_DIR/*.$FILE_EXT -brightness-contrast $COMPRESS_BW_BRIGHTNESS -compress Group4 -type bilevel TIFF:- | magick - $WORK_FILE
    elif [[ "$COMPRESS_TYPE" == "posterize" ]]; then
        magick $WORK_DIR/*.$FILE_EXT -posterize $COMPRESS_POSTERIZE_LEVEL $WORK_FILE
    elif [[ "$COMPRESS_TYPE" == "jpeg" ]]; then
        magick mogrify -format JPEG -quality 80 $WORK_DIR/*.$FILE_EXT
        magick $WORK_DIR/*.JPEG $WORK_FILE
    elif [[ "$COMPRESS_TYPE" == "webp" ]]; then
        for file in $WORK_DIR/*.$FILE_EXT; do cwebp -q 100 -lossless "$file" -o "${file%.$FILE_EXT}.webp"; done
        magick $WORK_DIR/*.webp $WORK_FILE
    else
        echo "[!] Unknown method for compression!"
        exit
    fi
}

continue_prompt() {
    read -p "When complete, press enter to continue..." 0</dev/tty
}

while read -r i; do
    echo "[!] Processing PDF: $i"
    rm -rf $WORK_DIR
    mkdir -p $WORK_DIR

    if [[ "$REMOVE_WATERMARK" == "true" ]]; then
        # Uncompress PDF
        echo "[*] Uncompressing PDF file"
        qpdf --qdf --object-streams=disable "$i" $WORK_FILE

        # Known watermark
        echo "[*] Removing known watermarks"
        sed -i "s/66F4591A8A6653776B618FCE700F89BD//g" $WORK_FILE # dse.pp text
        sed -i "s/\ http:\/\/dsepp.com//g" $WORK_FILE # dse.pp link
        sed -i "s/\(Provided by dse.life\|Provided \|by \|dse.life\)//g" $WORK_FILE # dse.life watermark
        sed -i "s/\x2E\x31\x36\x31\x20\x30\x20\x6C//g" $WORK_FILE # dse.life watermark underline
        sed -i 'H;1h;$!d;x; s/\x77\n\x30\x20\x2D\x31\x36\x2E\x38\x35\x20\x6D//g' $WORK_FILE # dse.life watermark underline
    else
        cp "$i" $WORK_FILE
    fi

    # Convert to black and white
    if [[ ! -z "$COMPRESS_TYPE" ]]; then
        echo "[*] Converting to black and white"

        echo "- Converting pages to image files"
        (
            cd $WORK_DIR
            if [[ "$EXTRACT_METHOD" == "ppm" ]]; then
                pdftoppm temp.pdf pages -r 300 -scale-to 6000
            elif [[ "$EXTRACT_METHOD" == "images" ]]; then
                pdfimages temp.pdf pages
            elif [[ "$EXTRACT_METHOD" == "magick" ]]; then
                magick -density 300 temp.pdf pages-%d.ppm
            else
                echo "[!] Unknown method for extraction!"
                exit
            fi
        )

        echo "Rearrange the files in $WORK_DIR if necessary."
        continue_prompt

        echo "- Compressing into PDF file"
        FILE_EXT="ppm"
        compgen -G "$WORK_DIR/*.ppm" > /dev/null || FILE_EXT="pbm"
        compress_pdf
        while true; do
            read -p "Is the output PDF file ($WORK_FILE) of satisfactory quality? [y/n] " yn 0</dev/tty
            case $yn in
                [Yy]* )
                    break
                    ;;

                [Nn]* )
                    echo "Please modify the ppm files in $WORK_DIR accordingly."
                    continue_prompt
                    compress_pdf
                    ;;

                * )
                    echo "Please answer yes or no."
                    ;;
            esac
        done
    fi

    # Extra questions
    if [[ "$ROTATION" == true ]]; then
        read -p "Please input the value (in degrees) you want all the PDF pages to rotate: " deg 0</dev/tty
        qpdf --rotate=+$deg --replace-input $WORK_FILE
    fi

    if [[ "$DRY_RUN" == "true" ]]; then
        echo "[*] Holding save (dry run is enabled)"
        continue_prompt
    fi

    # Save
    echo "[*] Saving file"
    if [[ "$SAVE_METHOD" == "gs" ]]; then
        gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/default -dNOPAUSE -dQUIET -dBATCH -sOutputFile=- -f $WORK_FILE -sPAPERSIZE=a4 -c "[ /Title () /DOCINFO pdfmark" | sponge $WORK_FILE
        pdftocairo -r 300 -pdf $WORK_FILE "$i"
    elif [[ "$SAVE_METHOD" == "qpdf" ]]; then
        qpdf $WORK_FILE "$i"
    else
        echo "[!] Unknown method for saving!"
        exit
    fi

    echo "[*] Cleaning up"
    rm -rf $WORK_DIR
done < <(find "$@" -type f)