The protection of privacy is at the forefront of concerns for many organizations that need to distribute information. One way to do this is to redact private information from an image or document before releasing it. Recently we had a customer ask how to do this with LEADTOOLS.

Using LEADTOOLS, a user would load an image or a document as an image, use the redaction annotation object to "black-out" the text, and then burn the redaction into the image. Once the protected information is redacted, the image can then be saved as a text searchable PDF so the remaining text can be indexed or searched.

After reviewing the forums and responses to some surveys we recently send out, I noticed that many developers are looking for the best way to convert an image to a black & white PDF file. LEADTOOLS offers at least two solutions:

Continuing my adventure of "Going Paperless", I needed an easy way to encrypt PDF files before I added them to Evernote. To do this, I used the LEADTOOLS PDFFile() class to add a user password to a file. I created a console application with code to register itself into the Windows Explorer shell. Now I can right click any PDF file and encrypt it with a password. The LEADTOOLS code to do this is very easy; it took me longer to figure out how to edit the registry to add the application to the Windows Explorer context menu then it did to use LEADTOOLS to add the password.

One call got it done:

new PDFFile( fileName, password ) {
   SecurityOptions = new PDFSecurityOptions {
      UserPassword = newPassword,
      EncryptionMode = PDFEncryptionMode.RC128Bit
   },
   CompatibilityLevel = PDFCompatibilityLevel.PDF15
}.Convert( 1, -1, null );

Low-resolution images can come from a variety of sources, but the most common source is probably screen capture. Screen capture images are usually 96 DPI on Windows. (This can vary depending on the user settings). Additionally, image representations of incoming faxes may also be considered low-res and fall under the resolution threshold acceptable for OCR. Typically, OCR engines require images of 200 or 300 DPI in order to achieve acceptable results.

Change Image Resolution

One easy solution for images that do not have noise or have complex structures is to change the resolution of the image before OCRing the image. This C# sample shows you how, then it gets the text from the image and outputs it to the console.

One of the new features of the latest LEADTOOLS V19 update is a re-factored load algorithm, which has resulted in greatly reduced load times of documents formats such as PDF, MS-Office formats 97-2013 (Word, Excel, and PowerPoint), and TXT. The increase in speed is directly related to the number of pages in the document; the more pages, the greater the increase of speed.

Below is a C# code snippet showing how to use the new feature with the new bits marked.