![]() "multi_lang.jpg", $opts ) // C) check the result $doc -> Save ( $output_path. png with options OCRModule :: ImageToPDF ( $doc, $input_path. "psychomachia_excerpt.pdf", 0 ) echo "Example 1: psychomachia_excerpt.png \n" //- // Example 2) Process document using multiple languages // A) Setup empty destination doc $doc = new PDFDoc ( ) // B) Setup options with multiple target languages, English will always be considered as secondary language $opts = new OCROptions ( ) $opts -> AddLang ( "rus" ) $opts -> AddLang ( "deu" ) // B) Run OCR on the. I've included the options I'm aware of, but if you feel I've missed any let me know in the comments.Save ( $output_path. There's some difficulty finding proper open-source, rather than commercial or copyleft licensed software to achieve this task.Įven when we find a library it's still never going to extract text in reading order perfectly 100% of the time, since PDF was never designed to support this. We reviewed a few of the options available to a developer looking to read text from a PDF in C# on. I couldn't find an immediately obvious API for text extraction and there seems to be an open issue for text extraction, but I thought I'd mention it as an option if you're looking to convert PDF to image, or work with the internal PDF structure. It also replaces the System.Drawing dependency of the original PDfSharp with the more cross-platform friendly ImageSharp library which means, as usual, you should check the licenses of the dependencies (there was some talk of changing the ImageSharp license recently). It seems to be primarily focused on creating, rather than reading, PDFs but also supports other operations. This is a port of the MIT licensed PdfSharp library to. Currently it restricts you to targeting 圆4 but this may change in future. NextToken ()) ĭocnet gives you the speed benefit of native libraries as well as the reassurance of running the PDF code which powers Chromium and by extension, Chrome. ReadAllBytes ( )) for ( var pageNum = 1 pageNum () while ( tokenizer. There's an unofficial fork of iTextSharp from back when it was LGPL licensed (this is still a copyleft license - note that this link is to LGPL v2.1 rather than v2) before the change to the AGPL license with some recent changes to port it to. ![]() This is quite an 'aggressive' license that cannot be used for commercial purposes unless you also release your entire source code as source available (controversial take, I don't really consider AGPL open source) under the AGPL, or buy a commercial license. Most versions of iTextSharp (now iText as of version 7) are covered by the AGPL. One of the more well established PDF libraries in C#. Consult someone who understands this stuff if licensing is a real issue for you. I'll be using the sample PDF found here but you can use any PDF file.įor the licensing discussion below - the traditional disclaimer that I am not a lawyer, I don't particularly understand software licenses. NET Core 2.1 on Windows 10 using Visual Studio 2017. If you don't want to run OCR and you don't want to fork out a considerable amount of money for commercially licensed PDF software, what are your options for getting text out of a PDF in C#?įor the following examples I'm targeting. They're not primarily designed to transmit the text in a useful way, it's pretty much a side effect of the requirement to render the document that it even contains text at all.įor this reason some people just run OCR against all PDF documents and rely on the OCR to extract text from what is, and I'm repeating myself here, basically an image. With that in mind there's no such thing as 'perfect' (or a lot of the time even passable) text extraction from PDFs. There are even some documents containing fonts where the text information has no actual relationship to the displayed glyphs, you might have encountered them before in these documents if you highlight and copy paste some text that appears 'normal' when you paste it to another application it's just nonsense. The text content included in a document mostly just defines where letters from a font should be drawn. The presence of fonts in the file helps applications that display PDFs draw text in (almost) the same way across platforms. The fact it contains text and font information is almost, but not quite, incidental. This means whatever platform you view it on, it should look (more-or-less) identical, whether you're on Windows, Linux, Chrome, Android, etc. At a very high level it's a set of images defining how the pages in the document should appear. To those unfamiliar with it I'd describe a PDF file as a picture. It's a good question and the answer lies in trade-offs made when the PDF format was designed. ![]() The question anyone who has tried to extract text from a PDF using C# will have asked themselves at one point or another is: why is this so complicated? ![]()
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