fritz-hh
986fbf63a4
- Introduce -s option to no ocr pages containing fonts - Solve issue with -f and -s if -C is not set
235 lines
11 KiB
Bash
Executable File
235 lines
11 KiB
Bash
Executable File
#!/bin/sh
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##############################################################################
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# Script aimed at OCRing a single page of a PDF file
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#
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# Copyright (c) 2013-14: fritz-hh from Github (https://github.com/fritz-hh)
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##############################################################################
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. "./src/config.sh"
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# Initialization of variables passed by arguments
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FILE_INPUT_PDF="$1" # PDF file containing the page to be OCRed
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PAGE_INFO="$2" # Various characteristics of the page to be OCRed
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NUM_PAGES="$3" # Total number of page of the PDF file (required for logging)
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TMP_FLD="$4" # Folder where the temporary files should be placed
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VERBOSITY="$5" # Requested verbosity
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LAN="$6" # Language of the file to be OCRed
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KEEP_TMP="$7" # Keep the temporary files after processing (helpful for debugging)
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PREPROCESS_DESKEW="$8" # Deskew the page to be OCRed
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PREPROCESS_CLEAN="$9" # Clean the page to be OCRed
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PREPROCESS_CLEANTOPDF="${10}" # Put the cleaned paged in the OCRed PDF
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OVERSAMPLING_DPI="${11}" # Oversampling resolution in dpi
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PDF_NOIMG="${12}" # Request to generate also a PDF page containing only the OCRed text but no image (helpful for debugging)
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FORCE_OCR="${13}" # Force to OCR, even if the page already contains fonts
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SKIP_TEXT="${14}" # Skip OCR on pages that contain fonts and include the page anyway
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TESS_CFG_FILES="${15}" # Specific configuration files to be used by Tesseract during OCRing
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##################################
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# Detect the characteristics of the embedded image for
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# the page number provided as parameter
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#
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# Param 1: page number
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# Param 2: PDF page width in pt
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# Param 3: PDF page height in pt
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# Param 4: temporary file path (Path of the file in which the output should be written)
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# Output: A file containing the characteristics of the embedded image. File structure:
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# DPI=<dpi>
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# COLOR_SPACE=<colorspace>
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# DEPTH=<colordepth>
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# Returns:
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# - 0: if no error occurs
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# - 1: in case the page already contains fonts (which should be the case for PDF generated from scanned pages)
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# - 2: in case the page contains more than one image
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##################################
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getImgInfo() {
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local page widthPDF heightPDF curImgInfo nbImg curImg propCurImg widthCurImg heightCurImg colorspaceCurImg depthCurImg dpi
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# page number
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page="$1"
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# width / height of PDF page (in pt)
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widthPDF="$2"
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heightPDF="$3"
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# path of the file in which the output should be written
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curImgInfo="$4"
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[ $VERBOSITY -ge $LOG_DEBUG ] && echo "Page $page: Size ${heightPDF}x${widthPDF} (h*w in pt)"
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# check if the page already contains fonts (which should not be the case for PDF based on scanned files
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[ `pdffonts -f $page -l $page "${FILE_INPUT_PDF}" | wc -l` -gt 2 ] && echo "Page $page: Page already contains font data !!!" && return 1
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# extract raw image from pdf file to compute resolution
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# unfortunately this image can have another orientation than in the pdf...
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# so we will have to extract it again later using pdftoppm
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pdfimages -f $page -l $page -j "$FILE_INPUT_PDF" "$curOrigImg" 1>&2
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# count number of extracted images
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nbImg=$((`ls -1 "$curOrigImg"* 2>/dev/null | wc -l`))
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if [ $nbImg -ne "1" ]; then
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[ $VERBOSITY -ge $LOG_WARN ] && echo "Page $page: Expecting exactly 1 image covering the whole page (found $nbImg). Cannot compute dpi value."
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return 2
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fi
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# Get characteristics of the extracted image
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curImg=`ls -1 "$curOrigImg"* 2>/dev/null`
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propCurImg=`identify -format "%w %h %[colorspace] %[depth]" "$curImg"`
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widthCurImg=`echo "$propCurImg" | cut -f1 -d" "`
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heightCurImg=`echo "$propCurImg" | cut -f2 -d" "`
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colorspaceCurImg=`echo "$propCurImg" | cut -f3 -d" "`
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depthCurImg=`echo "$propCurImg" | cut -f4 -d" "`
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[ $VERBOSITY -ge $LOG_DEBUG ] && echo "Page $page: Size ${heightCurImg}x${widthCurImg} (in pixel)"
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# compute the resolution of the image (making the assumption that x & y resolution are equal)
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# and round it to the nearest integer
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dpi=`echo "scale=5;sqrt($widthCurImg*72*$heightCurImg*72/$widthPDF/$heightPDF)+0.5" | bc`
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dpi=`echo "scale=0;$dpi/1" | bc`
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# save the image characteristics
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echo "DPI=$dpi" > "$curImgInfo"
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echo "COLOR_SPACE=$colorspaceCurImg" >> "$curImgInfo"
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echo "DEPTH=$depthCurImg" >> "$curImgInfo"
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return 0
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}
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page=`echo $PAGE_INFO | cut -f1 -d" "`
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[ $VERBOSITY -ge $LOG_INFO ] && echo "Processing page $page / $NUM_PAGES"
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# get width / height of PDF page (in pt)
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widthPDF=`echo $PAGE_INFO | cut -f2 -d" "`
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heightPDF=`echo $PAGE_INFO | cut -f3 -d" "`
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# create the name of the required temporary files
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curOrigImg="$TMP_FLD/${page}.orig-img" # original image available in the current PDF page
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# (the image file may have a different orientation than in the pdf file)
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curHocr="$TMP_FLD/${page}.hocr" # hocr file to be generated by the OCR SW for the current page
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curOCRedPDF="$TMP_FLD/${page}.ocred.pdf" # PDF file containing the image + the OCRed text for the current page
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curOCRedPDFDebug="$TMP_FLD/${page}.ocred.todebug.pdf" # PDF file containing data required to find out if OCR worked correctly
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curImgInfo="$TMP_FLD/${page}.orig-img-info.txt" # Detected characteristics of the embedded image
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# auto-detect the characteristics of the embedded image
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depthCurImg="8" # default color depth
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colorspaceCurImg="sRGB" # default color space
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dpi=$DEFAULT_DPI # default resolution
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getImgInfo "$page" "$widthPDF" "$heightPDF" "$curImgInfo"
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ret_code="$?"
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# Handle pages that already contain a text layer
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if ([ "$ret_code" -eq "1" ] && [ "$FORCE_OCR" -eq "0" ] && [ "$SKIP_TEXT" -eq "0" ]); then
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echo "Page $page: Exiting... (Use the -f option to force OCR, even though fonts are available in the input file. Or use -s to include the page as is (no OCR) in the output file)" && exit $EXIT_BAD_INPUT_FILE
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elif ([ "$ret_code" -eq "1" ] && [ "$SKIP_TEXT" -eq "1" ]); then
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[ $VERBOSITY -ge $LOG_INFO ] && echo "Page $page: Skipping processing because page contains text..."
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pdfseparate -f $page -l $page "${FILE_INPUT_PDF}" "$curOCRedPDF"
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exit 0
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elif ([ "$ret_code" -eq "1" ] && [ "$FORCE_OCR" -eq "1" ]); then
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[ $VERBOSITY -ge $LOG_WARN ] && echo "Page $page: OCRing anyway, assuming a default resolution of $dpi dpi"
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# in case the page contains more than one image, warn the user but go on with default parameters
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elif [ "$ret_code" -eq "2" ]; then
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[ $VERBOSITY -ge $LOG_WARN ] && echo "Page $page: Continuing anyway, assuming a default resolution of $dpi dpi"
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else
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# read the image characteristics from the file
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dpi=`cat "$curImgInfo" | grep "^DPI=" | cut -f2 -d"="`
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colorspaceCurImg=`cat "$curImgInfo" | grep "^COLOR_SPACE=" | cut -f2 -d"="`
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depthCurImg=`cat "$curImgInfo" | grep "^DEPTH=" | cut -f2 -d"="`
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fi
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# perform oversampling if the resolution is not sufficient to get good OCR results
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if [ "$dpi" -lt "$OVERSAMPLING_DPI" ]; then
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[ $VERBOSITY -ge $LOG_WARN ] && echo "Page $page: Low image resolution detected ($dpi dpi). Performing oversampling ($OVERSAMPLING_DPI dpi) to try to get better OCR results."
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dpi="$OVERSAMPLING_DPI"
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elif [ "$dpi" -lt "200" ]; then
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[ $VERBOSITY -ge $LOG_WARN ] && echo "Page $page: Low image resolution detected ($dpi dpi). If needed, please use the \"-o\" to try to get better OCR results."
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fi
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# Identify if page image should be saved as ppm (color), pgm (gray) or pbm (b&w)
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ext="ppm" # by default (color image) the extension of the extracted image is ppm
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opt="" # by default (color image) no option as to be passed to pdftoppm
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if [ "$colorspaceCurImg" = "Gray" ] && [ "$depthCurImg" = "1" ]; then # if monochrome (b&w)
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ext="pbm"
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opt="-mono"
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elif [ "$colorspaceCurImg" = "Gray" ]; then # if gray
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ext="pgm"
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opt="-gray"
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fi
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curImgPixmap="$TMP_FLD/$page.$ext"
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curImgPixmapDeskewed="$TMP_FLD/$page.deskewed.$ext"
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curImgPixmapClean="$TMP_FLD/$page.cleaned.$ext"
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# extract current page as image with correct orientation and resolution
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[ $VERBOSITY -ge $LOG_DEBUG ] && echo "Page $page: Extracting image as $ext file (${dpi} dpi)"
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! pdftoppm -f $page -l $page -r $dpi $opt "$FILE_INPUT_PDF" > "$curImgPixmap" \
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&& echo "Could not extract page $page as $ext from \"$FILE_INPUT_PDF\". Exiting..." && exit $EXIT_OTHER_ERROR
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# if requested deskew image (without changing its size in pixel)
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widthCurImg=$(($dpi*$widthPDF/72))
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heightCurImg=$(($dpi*$heightPDF/72))
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if [ "$PREPROCESS_DESKEW" -eq "1" ]; then
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[ $VERBOSITY -ge $LOG_DEBUG ] && echo "Page $page: Deskewing image"
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! convert "$curImgPixmap" -deskew 40% -gravity center -extent ${widthCurImg}x${heightCurImg} "$curImgPixmapDeskewed" \
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&& echo "Could not deskew \"$curImgPixmap\". Exiting..." && exit $EXIT_OTHER_ERROR
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else
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ln -s `basename "$curImgPixmap"` "$curImgPixmapDeskewed"
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fi
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# if requested clean image with unpaper to get better OCR results
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if [ "$PREPROCESS_CLEAN" -eq "1" ]; then
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[ $VERBOSITY -ge $LOG_DEBUG ] && echo "Page $page: Cleaning image with unpaper"
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! unpaper --dpi $dpi --mask-scan-size 100 \
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--no-deskew --no-grayfilter --no-blackfilter --no-mask-center --no-border-align \
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"$curImgPixmapDeskewed" "$curImgPixmapClean" 1> /dev/null \
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&& echo "Could not clean \"$curImgPixmapDeskewed\". Exiting..." && exit $EXIT_OTHER_ERROR
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else
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ln -s `basename "$curImgPixmapDeskewed"` "$curImgPixmapClean"
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fi
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# perform OCR
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[ $VERBOSITY -ge $LOG_DEBUG ] && echo "Page $page: Performing OCR"
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! tesseract -l "$LAN" "$curImgPixmapClean" "$curHocr" hocr $TESS_CFG_FILES 1> /dev/null 2> /dev/null \
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&& echo "Could not OCR file \"$curImgPixmapClean\". Exiting..." && exit $EXIT_OTHER_ERROR
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# Tesseract names the output files differently in some distributions.
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if [ -e "$curHocr.html" ]; then
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mv "$curHocr.html" "$curHocr"
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elif [ -e "$curHocr.hocr" ]; then
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mv "$curHocr.hocr" "$curHocr"
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elif [ ! -e "$curHocr" ]; then
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echo "\"$curHocr[.html|.hocr]\" not found. Exiting..." && exit $EXIT_OTHER_ERROR
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fi
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# embed text and image to new pdf file
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if [ "$PREPROCESS_CLEANTOPDF" -eq "1" ]; then
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image4finalPDF="$curImgPixmapClean"
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else
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image4finalPDF="$curImgPixmapDeskewed"
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fi
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[ $VERBOSITY -ge $LOG_DEBUG ] && echo "Page $page: Embedding text in PDF"
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! python2 $SRC/hocrTransform.py -r $dpi -i "$image4finalPDF" "$curHocr" "$curOCRedPDF" \
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&& echo "Could not create PDF file from \"$curHocr\". Exiting..." && exit $EXIT_OTHER_ERROR
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# if requested generate special debug PDF page with visible OCR text
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if [ $PDF_NOIMG -eq "1" ] ; then
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[ $VERBOSITY -ge $LOG_DEBUG ] && echo "Page $page: Embedding text in PDF (debug page)"
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! python2 $SRC/hocrTransform.py -b -r $dpi "$curHocr" "$curOCRedPDFDebug" \
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&& echo "Could not create PDF file from \"$curHocr\". Exiting..." && exit $EXIT_OTHER_ERROR
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fi
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# delete temporary files created for the current page
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# to avoid using to much disk space in case of PDF files having many pages
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if [ $KEEP_TMP -eq 0 ]; then
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rm -f "$curOrigImg"*
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rm -f "$curHocr"
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rm -f "$curImgPixmap"
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rm -f "$curImgPixmapDeskewed"
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rm -f "$curImgPixmapClean"
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rm -f "$curImgInfo"
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fi
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exit 0
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