diff options
Diffstat (limited to 'extras/mkocrpdf.sh')
| -rw-r--r-- | extras/mkocrpdf.sh | 36 |
1 files changed, 27 insertions, 9 deletions
diff --git a/extras/mkocrpdf.sh b/extras/mkocrpdf.sh index 3a01559..9113963 100644 --- a/extras/mkocrpdf.sh +++ b/extras/mkocrpdf.sh @@ -3,23 +3,41 @@ # # Makes a PDF with embedded text extracted by tesseract # Requires imagemagick, pdftk, hocr2pdf and tesseract 3 +# +# Note: Unfortunately tesseract works much better if one first +# makes the image to be OCRed significantly larger. This +# script does that, then reduces the results back down +# to create a reasonable size PDF. echo 'tessedit_create_hocr 1' > hocr for i in `ls *png` do - a=`basename $i .png` - echo processing $a + # create a much bigger version of the page image + width=`identify "$i" | awk '{print $3}' | sed 's/x.*//'` + bigwidth=`expr $width \* 4` + convert "$i" -geometry ${bigwidth}x "$i.big.png" + + # scan the page image + tesseract "$i.big.png" "$i.big.png" hocr 2>&1 | sed '/Tesseract Open Source OCR Engine/d' + + # this reduces all bbox information to match the original image size + sedrule=`cat "$i.big.png.html" \ + | sed -e 's/</\n/g' \ + | sed -e '/bbox/!d' -e 's/.*bbox//g' -e 's/".*//g' -e "s/'.*//g" \ + | awk '{ printf("s/bbox %d %d %d %d/bbox",$1,$2,$3,$4); + for(i=1;i<5;i++) printf(" %d", $i/4); + printf("/g\n")}'` + sed -e 's/\.big\.png//g' -e "$sedrule" < "$i.big.png.html" > "$i.html" - # unfortunately tesseract seems to work much better with a - # resized larger image - convert $i -geometry 1000x $a.big.png - tesseract $a.big.png $a hocr 2>/dev/null + # combine the image and hocr into a pdf page + # Note: hocr2pdf has a habit of segfaulting, so fall back to convert + hocr2pdf -i "$i" -o "$i.pdf" < "$i.html" || convert "$i" "$i.pdf" - # hocr2pdf has a habit of segfaulting, so fall back to convert - hocr2pdf -i $a.big.png -o $a.pdf < $a.html || convert $a.big.png $a.pdf - rm -f $a.html $a.big.png + # remove working files + rm -f "$i.big.png" "$i.big.png.html" "$i.html" done +# cat the pdf pages together pdftk *pdf cat output book.pdf rm -f [0-9]*pdf hocr |