Redacting a PDF is the process of permanently removing sensitive or confidential information from PDF documents. The Syncfusion .NET PDF library provides an easy way to redact PDF documents. This repository contains the example to redact PDF document in below ways using C#.
- Redact PDF without color
- Redact PDF with fill color
- Redact PDF with redaction code
- Redact from PDF image
| Sample name | Description |
|---|---|
| PDFRedaction | Sample to redact PDF document in multiple ways. |
Here we load the PDF document and just remove the email address from it (leave the area blank). You can find the code example in the method named btnRedactPDFwithoutColor in MainWindow.xaml.cs file.
//Load a PDF document for redaction
PdfLoadedDocument ldoc = new PdfLoadedDocument("../../Input/RedactPDF.pdf");
//Get first page from document
PdfLoadedPage lpage = ldoc.Pages[0] as PdfLoadedPage;
//Create PDF redaction for the page
PdfRedaction redaction = new PdfRedaction(new RectangleF(340,120,140,20));
//Adds the redaction to loaded 1st page
lpage.Redactions.Add(redaction);
//Save the redacted PDF document to disk
ldoc.Save("RedactedPDF.pdf");
//Close the document instance
ldoc.Close(true);As you can see in the screenshot, the email address in the PDF file is completely removed without any trace and you cannot find or select the redacted content.
Now we redact the PDF document with fill color. This will completely remove the content from the PDF and apply red color over the redacted area. You can find the code example in the method named btnRedactPDFwithColor_Click in MainWindow.xaml.cs file.
//Create PDF redaction for the page
PdfRedaction redaction = new PdfRedaction(new RectangleF(340,120,140,20), System.Drawing.Color.Red);
//Adds the redaction to loaded page
lpage.Redactions.Add(redaction);
Certain PDF files, such as invoice, government official forms, contains text or images that are positioned at the fixed position in the PDF page. For example, employee addresses in W-4 tax forms will always be in the same place and can be redacted under the exemption code of US FOIA (b) (6). You can find the code example in the method named btnRedactPDFwithCodes_Click in MainWindow.xaml.cs file.
//Create redaction area for redacting telephone number with code set.
RectangleF redactionBound = new RectangleF(50, 568, 120, 13);
PdfRedaction redaction = new PdfRedaction(redactionBound);
redaction.Appearance.Graphics.DrawRectangle(PdfBrushes.Black, new RectangleF(0, 0, redactionBound.Width, redactionBound.Height));
redaction.Appearance.Graphics.DrawString("(b) (6)", new PdfStandardFont(PdfFontFamily.Helvetica, 11), PdfBrushes.White, new PointF(0, 0));
//Adds the redaction to loaded page
lpage.Redactions.Add(redaction);
//Create redaction area for redacting address with code set.
RectangleF addressRedaction = new RectangleF(50, 592, 75, 13);
redaction = new PdfRedaction(addressRedaction);
redaction.Appearance.Graphics.DrawRectangle(PdfBrushes.Black, new RectangleF(0, 0, addressRedaction.Width, addressRedaction.Height));
redaction.Appearance.Graphics.DrawString("(b) (6)", new PdfStandardFont(PdfFontFamily.Helvetica, 11), PdfBrushes.White, new PointF(0, 0));
lpage.Redactions.Add(redaction);
Sometimes, we may have social security numbers (SSN), employee identification numbers, addresses, email IDs, in a scanned PDF file. In those cases, it is very hard to search manually for a specific pattern to redact it. Syncfusion offers an efficient way to find sensitive information in a PDF image using OCR library and redact it from the PDF file.
To do this, copy the Tesseract binaries and language data from the NuGet package location to your application and refer the path to your OCR processor. You can find the code example in the method named btnRedactPDFImage_Click in MainWindow.xaml.cs file.
//Initialize the OCR processor
using (OCRProcessor processor = new OCRProcessor(@"../../TesseractBinaries/3.02/"))
{
//Load the PDF document
PdfLoadedDocument lDoc = new PdfLoadedDocument(@"../../Input/FormWithSSN.pdf");
//Load the PDF page
PdfLoadedPage loadedPage = lDoc.Pages[0] as PdfLoadedPage;
//Language to process the OCR
processor.Settings.Language = Languages.English;
//Extract image and information from the PDF for processing OCR
PdfImageInfo[] imageInfoCollection = loadedPage.ImagesInfo;
foreach (PdfImageInfo imgInfo in imageInfoCollection)
{
Bitmap ocrImage = imgInfo.Image as Bitmap;
OCRLayoutResult result = null;
float scaleX = 0, scaleY = 0;
if (ocrImage != null)
{
//Process OCR by providing loaded PDF document, Data dictionary and language
string text = processor.PerformOCR(ocrImage, @"../../LanguagePack/", out result);
//Calculate the scale factor for the image used in the PDF
scaleX = imgInfo.Bounds.Height / ocrImage.Height;
scaleY = imgInfo.Bounds.Width / ocrImage.Width;
}
//Get the text from page and lines.
foreach (var page in result.Pages)
{
foreach (var line in page.Lines)
{
if (line.Text != null)
{
//Regular expression for social security number
var ssnMatches = Regex.Matches(line.Text, @"(\d{3})+[ -]*(\d{2})+[ -]*\d{4}", RegexOptions.IgnorePatternWhitespace);
if (ssnMatches.Count >= 1)
{
RectangleF redactionBound = new RectangleF(line.Rectangle.X * scaleX, line.Rectangle.Y * scaleY,
(line.Rectangle.Width - line.Rectangle.X) * scaleX, (line.Rectangle.Height - line.Rectangle.Y) * scaleY);
//Create PDF redaction for the found SSN location
PdfRedaction redaction = new PdfRedaction(redactionBound);
//Adds the redaction to loaded page
loadedPage.Redactions.Add(redaction);
}
}
}
}
}
//Save the redacted PDF document in the disk
lDoc.Save("RedactedPDF.pdf");
lDoc.Close(true);
Process.Start("RedactedPDF.pdf");
}
- Download this project to a location in your disk.
- Open the solution file using Visual Studio.
- Rebuild the solution to install the required NuGet package.
- Run the application.
- Product page: Syncfusion PDF Framework
- Documentation page: Syncfusion .NET PDF library
- Online demo: Syncfusion .NET PDF library - Online demos
- Blog: Syncfusion .NET PDF library - Blog
- Knowledge Base: Syncfusion .NET PDF library - Knowledge Base
- EBooks: Syncfusion .NET PDF library - EBooks
- FAQ: Syncfusion .NET PDF library - FAQ
- For any other queries, reach our Syncfusion support team or post the queries through the community forums.
- Request new feature through Syncfusion feedback portal.
This is a commercial product and requires a paid license for possession or use. Syncfusion’s licensed software, including this component, is subject to the terms and conditions of Syncfusion's EULA. You can purchase a licnense here or start a free 30-day trial here.
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