Cleaning Up 1-Bit Images

(Document/Medical) Scanned documents often contain a number of undesirable elements, including dots, blobs, lines, borders, and hole punches. LEADTOOLS provides a number of classes that improve the appearance of scanned documents by removing dots, blobs, lines, borders, hole punches, inverted page, inverted text, bumps, and nicks. These classes are listed in the following table:

Leadtools.ImageProcessing.Core Class Description
SmoothCommand Smoothes the bumps and fills in the nicks of a 1-bit black and white image.
BorderRemoveCommand Removes the black borders in a 1-bit black and white image.


Removes horizontal and vertical lines in a 1-bit black and white image.


Finds and removes dots and specks of various sizes.


Finds and removes hole punches.
InvertedTextCommand Finds and modifies areas of inverted text in a 1-bit black and white image.
InvertedPageCommand Checks and auto-corrects an inverted image (1-bit or color).
HighQualityRotateCommand Performs high quality rotation on a 1-bit black and white image.

Each of these classes utilizes flags that allow you to obtain a LEAD region (Leadtools.ImageProcessing.Core only) or a Windows region (all three) that contains all the elements removed from a document. In addition, event handlers allow you to provide customized region processing, as well as create your own composite of the removed regions.

Images can be straightened by using the following commands:

Leadtools.ImageProcessing.Core Class Description
DeskewCommand Deskewing.

For information about pre-processing color images, see Pre-processing Images for OCR.

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