PdfImage.RecompressWithGroup3Fax Method (Int32)

Recompresses image data using Group 3 CCITT facsimile (fax) encoding and specified threshold level.

Namespace:  BitMiracle.Docotic.Pdf
Assembly:  BitMiracle.Docotic.Pdf (in BitMiracle.Docotic.Pdf.dll)


public void RecompressWithGroup3Fax(
	int thresholdLevel
Public Sub RecompressWithGroup3Fax ( 
	thresholdLevel As Integer


Type: System.Int32
The threshold level.


Using Group 3 CCITT facsimile (fax) encoding will cause image data to be converted to bilevel (black-and-white) format if necessary.

The threshold level is used to decide which pixels are white and which are black when converting image data to black-and-white format.

The threshold level value should be between 0 and 255 inclusive. A threshold value 0 means that library should use midpoint between most light and dark pixels as a threshold value.

If the image contains some scanned document or other data with mostly white background pixels and mostly black foreground pixels then threshold level of 189 or higher is recommended to preserve most of the data.

This method throws UnsupportedImageException when used on an inline image. You can check IsInline property before invoking this method.

For a mask image, this method emits a warning in logs and does nothing. A mask image is an image with IsMask equal to true.

See Also