I have just recently been experimenting with parsing the text data from a PDF document using iTextSharp in a VB2010 app. the document doesn't contain any images or other fancy elements, just text. Ive read some articles and used some code snippets and it looks promising. However, what Ive been trying to do is just parse out the body of each page, minus a header or footer. I haven't found any guidance for that particular function.
Currently using the snippet found here Reading PDF content with itextsharp dll in VB.NET or C# but it parses all text in a page. There's got to be a way to just get the body. Or at least I hope so.
PDFs generally do not contain information about logical structure of contained text.
So there are no headers, footers, body, paragraphs and anything like this in a PDF. There is only bunch of operations like "draw this glyph here", "move to this position and draw that group of glyphs there". I wrote glyph and not character because PDFs are not required to contain readable text. Only visual appearance required to be specified.
One exception is Tagged PDF but most of PDFs in the wild are not tagged.
Given all of the above you are probably left with following approach:
Extract all text from each page
Analyze text and find similar parts at the beginning / end of each page
Remove similar parts
This is a heuristic-based detection, so it probably won't always give excellent results.
Related
I am exploring couple of third party components to work with PDF through C#. These are Aspose.pdf.net and iTextSharp. Following are the details about what I am exploring them for:
I have some PDFs that contain sensitive information in form of text, like name of person, city, etc.
These PDFs need to be duplicated into another copy but while creating duplicated copy, sensitive text needs to be searched & replaced with some dummy text. The replacement is essential to avoid tracing original information, by any fraudulent means.
Also, the replaced text requires to be redacted.
Finding text is expected to support RegEx, as there could be variations of text that needs to be masked.
Could you please assist me how can this be done using iTextShart.
Thanks in advance.
iTextSharp is capable of complete redaction(both visual as well as the data stored in the pdf) using the PdfSweep module (http://itextpdf.com/itext7/pdfsweep).
In order to have the redaction happen after text search you'd have to:
Extract the text from the document (can be done using iText).
Search through the extracted text and obtain the positions of the text you want redacted. (needs an implementation from your side)
Use these positions to define where PdfSweep has to redact. (a couple of lines of code)
By default, PdfSweep visualy redacts by drawing coloured bars over the locations, and internally removes the text and any image.
While it is technically possible to use iText to fill the redacted positions with some dummy text, the implementation thereof has a number of pitfalls.
PdfSweep is closed source module for iText7, you can contact our sales team for more information on the licensing.
I have a visual basic program that extracts text from a PDF and imports the text into excel. It relies on reading the text like a human, reading left to right across the page. However, there are instances on this particular PDF where if I go to select the text with my mouse, I click and drag straight across but Adobe starts to select/highlight words on the above and below lines before continuing to highlight across the page. This gives me data that I do not want/need. The page has renderable text and is not from a scanned document.
Is there a way to "reset" the way Adobe interprets the text on the PDF? Since the information on the left is far from the information on the right, it treats them almost like separate columns.
I've tried saving the PDF in different formats such as a txt or postscript and distilling to another PDF but they all seem to result in the same outcome. This is weird to me because I have other similar PDFs where this isn't an issue.
Any help or thoughts would be greatly appreciated, thanks.
As PDF (in its basic form) essentially means placing strings on a canvas, the concept of "sentence" or "reading order" is not built in.
In order to extract text, you would have to read out the bounding box of the piece of text, and then use some logic and heuristics to assemble your text based on the coordinates of the bounding box.
Things can be easier if the PDF is a structured PDF, where the text contents is embedded as text in the document. This is also the prime requirement for an accessible document. So, if your document is accessible, you can rely on the structure for the correct reading order.
I am attempting to gain a better understanding of how a PDF stores text. Generally speaking, when a PDF is created from an application like MS Word (or in my case SQL Server Reporting Services), how is text stored by the PDF? I would hope that the resulting document isn't OCR'ed in this particular scenario the way it would be if the original PDF document had been created from an image.
To get a bit more detailed, I am trying to understand how text extractors for PDFs work. My initial understanding of PDF was that it stored (PostScript) instructions on how to draw the "image" of the document to a page or a printer, and that there was no actual text contained within the document itself. Subsequently, I was thinking that a text extractor might reverse-engineer such instructions to generate the text that the PDF would otherwise generate. I am not confident of this, though.
PDF contains several different types of objects; not only vectorial or raster drawing instructions. Text in in particular is represented by text elements. These include a string of characters that should be drawn at certain positions using a specific font.
Text extraction from PDFs can be a complicated affair because the file format is oriented for page layout. A text element may be an entire paragraph, or a single character. Even a single word may consist of several text elements if different typefaces are mixed. Also, the characters are not necessarily encoded in a standard encoding such as Unicode. They may be encoded in a way specific to a particular font.
If you are lucky enough to deal with Tagged PDF files such as PDF/A or PDF/UA, text extraction can be a lot easier because text spans are identified as such, and a mapping to Unicode characters is defined.
Wikipedia doesn't have the complete specification but does serve as an introduction: http://en.wikipedia.org/wiki/Portable_Document_Format#Text
I am trying to make an iOS app which would extract plain text from a pdf file and display it in a UITextView. Its simply not a pdf reader to view a pdf file but i would later wish to perform certain operations on that text.
I have already googled a lot but still not able to get an exact solution.
i already tried using https://github.com/zachron/pdfiphone
but the files are using ARMV6 architecture which seems obsolete with xcode 4.5
And if anyone can suggest some exact and non-confusing code using Quartz-2d framework of iOS then it would be great.
Here is An Sample code to Extract text from PDF Hope this Might Help You.
https://github.com/zachron/pdfiphone
This is a library to get the text out of a PDF for the iPhone.
Another Demo is there Which uses OCR technology find the link below
https://github.com/nolanbrown/Tesseract-iPhone-Demo
Also Check this page of the Quartz 2D Programming Guide, it covers everything you need to open and parse a PDF file in iOS. Note that it is not a simple task, since there's no method to extract the full text in one line. You have to work with the data as an input stream, using a CGPDFScanner
Two Other Libraries
https://github.com/KurtCode/PDFKitten/
https://github.com/mobfarm/FastPdfKit
This question comes up all the time. It is VERY hard to extract text from PDF in general. The PDF specification is not designed with text extraction in mind. There are many libraries that try to do the job, essentially by reconstructing the text from the geometric placement of the individual glyphs. These libraries have varying degrees of success, but will all fail on certain PDF documents. In fact, some PDF documents have Glyphs but no way to associate the glyph with a character. For these documents it is simply not possible to extract text, short of using some kind of OCR approach.
PDF is designed as a read-only format that is portable in the sense that a PDF document will be rendered identically on any platform. That is what it is best at, and what it should be used for.
If text is to be edited, do not use PDF.
Here (Extracting text from pdf using objective-c), I found an answer to your question and it works. But not so fine as i need it :(
it can extract only ascii
it return me only one paragraph
Good luck.
I'm sure this is just a google search away, but I can't find the right search terms to find what I'm looking for.
I've created a DataPackage that has both HTML annd plain text content. I've used this in my copy and my sharing code and it works fine. I now want to create RTF output as some apps don't seem to accept HTML clipboard content.
I'm looking for a good guide to making RTF text that can be added to the DataPackage. I just need simple formatting including changing the font family, font size, font weight and adding newlines. The data comes from a list of objects taht I want to serialise as RTF, not from a text control on the screen.
WordPad outputs fairly clean RTF and some other text editors do as well. If that's not enough, you can download the RTF Specification 1.9.1 although like any specification that's probably overkill for what you're doing.
You can also use the SaveToStream method on the Document property of a RichEditBox from a Metro style app to share out as well.