fritz-hh
4188d702ed
Added compuation of resolution of each PDF page Added extract of image of pgm if colorspace is Gray (to speed up computation and save space)
93 lines
3.1 KiB
Bash
93 lines
3.1 KiB
Bash
#!/bin/sh
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echo "usage: ./scan-archive.sh filename.pdf"
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LAN="eng"
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KEEP_TMP="1"
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infile="$1"
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tmp="./tmp"
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FILE_SIZEPAGES="$tmp/infile-page-sizes.txt"
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# delete tmp files
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rm -r -f "${tmp}"
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mkdir -p "${tmp}"
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# get the size of each pdf page (width / height) in pt (inch*72)
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echo "Extracting size of each page (in pt)"
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identify -format "%w %h\n" "$infile" > "$FILE_SIZEPAGES"
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sed -I "" '/^$/d' "$FILE_SIZEPAGES" # removing empty lines (last one should be)
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numpages=`cat "$FILE_SIZEPAGES" | wc -l`
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echo "PDF file has $numpages pages"
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# Itterate the pages of the pdf file
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page="1"
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cat "$FILE_SIZEPAGES" | while read pageSize ; do
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echo "Page $page: Computing embedded image resolution"
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# get width / height of PDF page
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heightPDF=`echo $pageSize | cut -f1 -d" "`
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widthPDF=`echo $pageSize | cut -f2 -d" "`
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# extract raw image from pdf file to compute resolution
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# unfortunatelly this image may not be rotated as in the pdf...
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# so we will have to extract it again later
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pdfimages -f $page -l $page -j "$infile" "$tmp/${page}_orig" 1>&2
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# count number of extracted images
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nbImg=`ls -1 "$tmp/${page}_orig"* | wc -l`
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[ $nbImg -ne "1" ] && echo "Not exactly 1 image on page $page. Exiting" && exit 1
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# Get the characteristic of the extracted image
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origImg=`ls -1 "$tmp/${page}_orig"*`
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origImg_woext=`echo "$origImg" | sed 's/\.[^.]*$//'`
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origImg_ext=`echo "$origImg" | sed 's/^.*[.]//'`
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propImg=`identify -format "%w %h %[colorspace]" "$origImg"`
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heightImg=`echo "$propImg" | cut -f1 -d" "`
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widthImg=`echo "$propImg" | cut -f2 -d" "`
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colorspaceImg=`echo "$propImg" | cut -f3 -d" "`
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# compute the resolution of the whole page (taking into account all images)
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dpi=$(($heightImg*72/$heightPDF))
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echo "Page $page: Resolution: ${dpi} dpi"
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# extract current page as image with right rotation
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echo "Page $page: Extracting image as ppm/pgm"
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if [ $colorspaceImg == "Gray" ]; then
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ext="pgm"
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opt="-gray"
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else
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ext="ppm"
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opt=""
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fi
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pdftoppm -f $page -l $page -r $dpi $opt $infile > "${tmp}/${page}.$ext"
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# improve quality of the image with unpaper to get better OCR results
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echo "Page $page: Preprocessing image with unpaper"
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unpaper --dpi $dpi --mask-scan-size 100 \
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--no-grayfilter --no-blackfilter --no-mask-center --no-border-align \
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"$tmp/$page.$ext" "$tmp/$page.forocr.$ext" 1> /dev/null
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# perform OCR
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echo "Page $page: Performing OCR"
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tesseract -l "$LAN" "$tmp/$page.forocr.$ext" "$tmp/$page.hocr" hocr 1> /dev/null 2> /dev/null
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mv "${tmp}/${page}.hocr.html" "$tmp/$page.hocr"
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# compress image to be put inside the pdf file
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echo "Page $page: Compressing image for final PDF file"
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convert -colorspace "$colorspaceImg" "$tmp/$page.forocr.$ext" "$tmp/$page.forpdf.jpg"
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# embed text and image to new pdf file
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echo "Page $page: Embedding text in PDF"
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python hocrTransform.py -r $dpi -i "$tmp/$page.forpdf.jpg" "$tmp/$page.hocr" "$tmp/${page}-ocred.pdf"
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# go to next page of the pdf
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page=$(($page+1))
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done
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# concatenate all pages
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pdftk ${tmp}/*-ocred.pdf cat output "${tmp}/ocred.pdf"
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# insert metadata
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# TODO
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# validate generated pdf file (compliance to PDF/A)
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#java -jar jhove/bin/JhoveApp.jar -m PDF-hul "$1" |egrep "Status|Message"
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