Public Sub ClearBackground( _ Optional ByVal ThrLevel As Double = 30 _ )
Scanning pages with white background scanned as grayscale and color typically produces off-white background. ClearBackground sets all pixels brighter than specified threshold to pure white. This makes image visually closer to the original document.
Method applies only to grayscale and color image.
ThrLevel = 0% threshold does not change an image
ThrLevel = 100% sets all color pixels to white
ThrLevel = 30% is recommended