Configure the accuracy for finding anchor controls

When you specify an anchor control in your document, the PDF Engine 3.0 stores information about the anchor control so that the system can later find it in the document during the test. By default, the PDF Engine 3.0 looks for a text or image that matches exactly what it expects to find. If the exact match requirement is too demanding and the PDF Engine 3.0 does not find an anchor control, you can configure a lower level of accuracy for finding the anchor control in the following cases:

  • You specify an image-type anchor control.

  • You specify a text-type anchor control but the underlying area is stored in the PDF file as an image. In this case, the PDF Engine 3.0 uses optical character recognition (OCR) to recognize text. OCR technology converts an image to text format by recognizing typed characters.

Accuracy is expressed as a percentage and it indicates the closeness of the match between what PDF Engine 3.0 expects to find and what it actually finds. By default, the PDF Engine 3.0 searches for image-type anchors with 99% accuracy and for text-type anchors with 100% accuracy. In some cases, however, this might be too demanding. For example, it could happen that OCR is not completely accurate when it converts image to text and mistakes a number "0" for a letter "o". Or a few pixels might be different between the image that it expects to find and what it actually finds. In these cases, it might make sense to lower the level of accuracy.

To configure the accuracy for finding an anchor control, follow the steps below:

  1. Go to the Modules section.

  2. Go to the ModuleAttribute that represents the anchor control for which you want to configure accuracy.

  3. If it is collapsed, expand the Properties pane by clicking on the Properties button on the top right corner of your window.

  4. In the Properties pane, set the value of the parameter Accuracy to an integer between 0 and 100. This number represents the accuracy level of the match.