initial version
This commit is contained in:
fritz-hh
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#!/bin/sh
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echo "usage: ./scan-archive.sh filename.pdf"
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infile="$1"
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lan="deu"
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dpi=300
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tmp="./tmp"
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# delete tmp files
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rm -r -f "${tmp}"
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mkdir -p "${tmp}"
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# detect the number of page of the pdf file
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numpages=`pdftk $infile "dump_data" | grep "NumberOfPages" | cut -f2 -d" "`
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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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while [ $page -le $numpages ]; do
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# extract image from current pdf page
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echo "Page $page: Extracting image from PDF"
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pdftk "$infile" cat $page output "${tmp}/${page}.pdf" > /dev/null
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pdftoppm -r $dpi "${tmp}/${page}.pdf" > "${tmp}/${page}.ppm"
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# improve quality of the image to get better ocr results
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echo "Page $page: Preprocessing image with unpaper"
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unpaper --dpi $dpi --mask-scan-size 100 \
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--no-grayfilter --no-blackfilter --no-mask-center --no-border-align \
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--overwrite "$tmp/$page.ppm" "$tmp/$page.forocr.ppm" > /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}/${page}.forocr.ppm" "${tmp}/${page}.hocr" hocr 1> /dev/null 2> /dev/null
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cp "${tmp}/${page}.hocr.html" "${tmp}/${page}.hocr"
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# embed text and image to new pdf file
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echo "Page $page: Embedding text in PDF"
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python hocrTransform.py "${tmp}/${page}.hocr" "${tmp}/${page}.forocr.ppm" "${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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# 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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from reportlab.pdfgen.canvas import Canvas
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from reportlab.lib.units import inch
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#from xml.etree.ElementTree import ElementTree
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from lxml import etree as ElementTree
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import Image, re, sys
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class HocrConverter():
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"""
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A class for converting documents to/from the hOCR format.
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For details of the hOCR format, see:
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http://docs.google.com/View?docid=dfxcv4vc_67g844kf
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See also:
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http://code.google.com/p/hocr-tools/
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Basic usage:
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Create a PDF from an hOCR file and an image:
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hocr = HocrConverter("path/to/hOCR/file")
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hocr.to_pdf("path/to/image/file", "path/to/output/file")
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"""
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def __init__(self, hocrFileName = None):
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self.hocr = None
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self.xmlns = ''
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self.boxPattern = re.compile('bbox((\s+\d+){4})')
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if hocrFileName is not None:
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self.parse_hocr(hocrFileName)
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def __str__(self):
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"""
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Return the textual content of the HTML body
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"""
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if self.hocr is None:
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return ''
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body = self.hocr.find(".//%sbody"%(self.xmlns))
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if body:
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return self._get_element_text(body).encode('utf-8') # XML gives unicode
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else:
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return ''
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def _get_element_text(self, element):
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"""
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Return the textual content of the element and its children
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"""
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text = ''
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if element.text is not None:
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text = text + element.text
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for child in element.getchildren():
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text = text + self._get_element_text(child)
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if element.tail is not None:
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text = text + element.tail
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return text
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def element_coordinates(self, element):
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"""
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Returns a tuple containing the coordinates of the bounding box around
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an element
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"""
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out = (0,0,0,0)
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if 'title' in element.attrib:
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matches = self.boxPattern.search(element.attrib['title'])
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if matches:
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coords = matches.group(1).split()
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out = (int(coords[0]),int(coords[1]),int(coords[2]),int(coords[3]))
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return out
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def parse_hocr(self, hocrFileName):
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"""
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Reads an XML/XHTML file into an ElementTree object
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"""
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self.hocr = ElementTree.ElementTree()
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self.hocr.parse(hocrFileName)
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# if the hOCR file has a namespace, ElementTree requires its use to find elements
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matches = re.match('({.*})html', self.hocr.getroot().tag)
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if matches:
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self.xmlns = matches.group(1)
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else:
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self.xmlns = ''
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def to_pdf(self, imageFileName, outFileName, fontname="Courier"):
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"""
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Creates a PDF file with an image superimposed on top of the text.
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Text is positioned according to the bounding box of the lines in
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the hOCR file.
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The image need not be identical to the image used to create the hOCR file.
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It can be scaled, have a lower resolution, different color mode, etc.
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"""
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if self.hocr is None:
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print "No hocr file provided. exiting"
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exit
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im = Image.open(imageFileName)
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if 'dpi' in im.info:
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width = float(im.size[0])/im.info['dpi'][0]
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height = float(im.size[1])/im.info['dpi'][1]
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else:
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# we have to make a reasonable guess
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# set to None for now and try again using info from hOCR file
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width = height = None
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# get dimensions of the OCR, which may not match the image
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ocr_dpi = (300, 300) # a default, in case we can't find it
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for div in self.hocr.findall(".//%sdiv[@class='ocr_page']"%(self.xmlns)):
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coords = self.element_coordinates(div)
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ocrwidth = coords[2]-coords[0]
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ocrheight = coords[3]-coords[1]
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if width is None:
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# no dpi info with the image
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# assume OCR was done at 300 dpi
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width = ocrwidth/300
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height = ocrheight/300
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ocr_dpi = (ocrwidth/width, ocrheight/height)
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break # there shouldn't be more than one, and if there is, we don't want it
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if width is None:
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# no dpi info within the image, and no help from the hOCR file either
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# this will probably end up looking awful, so issue a warning
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print "Warning: DPI unavailable for image %s. Assuming 300 DPI."%(imageFileName)
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width = float(im.size[0])/300
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height = float(im.size[1])/300
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# create the PDF file
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pdf = Canvas(outFileName, pagesize=(width*inch, height*inch), pageCompression=1) # page size in points (1/72 in.)
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# put the image on the page, scaled to fill the page
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#pdf.drawInlineImage(im, 0, 0, width=width*inch, height=height*inch)
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# check if element with class 'ocrx_word' are available
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# otherwise use 'ocr_line' as fallback
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elemclass="ocr_line"
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if self.hocr.find(".//%sspan[@class='ocrx_word']" %(self.xmlns)) is not None:
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elemclass="ocrx_word"
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for elem in self.hocr.findall(".//%sspan[@class='%s']" % (self.xmlns, elemclass)):
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elemtxt=self._get_element_text(elem).rstrip()
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if len(elemtxt) == 0:
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continue
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coords = self.element_coordinates(elem)
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# compute font size according to bbox coordinates
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fontsize=(coords[3]-coords[1])/(ocr_dpi[1]*(0.35146/25.4))
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# draw the bbox border
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#pdf.rect((float(coords[0])/ocr_dpi[0])*inch, (height*inch)-(float(coords[3])/ocr_dpi[1])*inch,(float(coords[2]-coords[0])/ocr_dpi[0])*inch, float(coords[3]-coords[1])/ocr_dpi[1]*inch, fill=0)
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text = pdf.beginText()
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text.setFont(fontname, fontsize)
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#text.setTextRenderMode(3) # invisible
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# set cursor to bottom left corner of bbox (adjust for dpi)
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text.setTextOrigin((float(coords[0])/ocr_dpi[0])*inch, (height*inch)-(float(coords[3])/ocr_dpi[1])*inch)
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# scale the width of the text to fill the width of the bbox
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text.setHorizScale((((float(coords[2])/ocr_dpi[0]*inch)-(float(coords[0])/ocr_dpi[0]*inch))/pdf.stringWidth(elemtxt, fontname, fontsize))*100)
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# write the text to the page
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text.textLine(elemtxt)
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pdf.drawText(text)
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# finish up the page and save it
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pdf.showPage()
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pdf.save()
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if __name__ == "__main__":
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if len(sys.argv) < 4:
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print 'Usage: python HocrConverter.py inputHocrFile inputImageFile outputPdfFile'
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sys.exit(1)
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hocr = HocrConverter(sys.argv[1])
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hocr.to_pdf(sys.argv[2], sys.argv[3])
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