←Select platform

GetOverlayImage Method


Gets the overlay image of this IOcrPage.

public RasterImage GetOverlayImage() 
Function GetOverlayImage() As RasterImage 
- (nullable LTRasterImage *)overlayImage:(NSError **)error 
public RasterImage getOverlayImage() 
RasterImage^ GetOverlayImage();  

Return Value

The overlay image or null of the page does not have one.


The overlay image of an IOcrPage will be used when the image is saved by an IOcrDocument in the following situations:

  • If the page contains a graphics zone (OcrZoneType.Graphics. The document will get the image to store in the document from the overlay image.

  • If the output format supports the "Image over text" feature. Such as PDF with Image/Text option. The document will get the image to store in the document from the overlay image.

By the default, the overlay image is the original image used to create the page. It is the same value obtained by calling GetRasterImage with OcrPageType.Original.

In some situation, the user might want use a different image as the overlay. For example, a smaller version is passed to the OCR engine to conserve memory while the original version will only be used on save purposes in a PDF with image/text option. You can call SetOverlayImage before saving the document (memory-based) or adding the page to the document (file-based) and the engine will use this new image as the overlay value. If auto-preprocessing was performed on the page through AutoPreprocess, then the same values might need to be applied to the overlay as well. Use GetPreprocessValues to get the accumulative values of any inversion, rotation or deskewing applied by the pre-processor.

To clear the temporarily overlay image, call SetOverlayImage with a null value.

To get the overlay image at any time, call GetOverlayImage. Note that this property will the same image reference passed to the last SetOverlayImage call. It will not return the original image.

The overlay image is not disposed by this IOcrPage.


For an example, refer to SetOverlayImage.


Target Platforms

Help Version 20.0.2020.4.2
Products | Support | Contact Us | Intellectual Property Notices
© 1991-2020 LEAD Technologies, Inc. All Rights Reserved.

Leadtools.Ocr Assembly