ConvertTo1BppSauvola(Int32,Single,Int32,Int32) Method

In This Topic

Converts a GdPicture image to a 1-bit (black and white) bitmap using the Sauvola local adaptive thresholding method and contrast normalization. This method is particularly efficient on documents with poor contrast.

Syntax

Visual Basic
C#
Delphi
JScript
Managed Extensions for C++
C++/CLI

'Declaration
 
Public Overloads Function ConvertTo1BppSauvola( _
   ByVal ImageID As Integer, _
   ByVal Factor As Single, _
   ByVal ContrastMinDif As Integer, _
   ByVal SmoothKernel As Integer _
) As GdPictureStatus

public GdPictureStatus ConvertTo1BppSauvola( 
   int ImageID,
   float Factor,
   int ContrastMinDif,
   int SmoothKernel
)

public function ConvertTo1BppSauvola( 
    ImageID: Integer;
    Factor: Single;
    ContrastMinDif: Integer;
    SmoothKernel: Integer
): GdPictureStatus;

public function ConvertTo1BppSauvola( 
   ImageID : int,
   Factor : float,
   ContrastMinDif : int,
   SmoothKernel : int
) : GdPictureStatus;

public: GdPictureStatus ConvertTo1BppSauvola( 
   int ImageID,
   float Factor,
   int ContrastMinDif,
   int SmoothKernel
)

public:
GdPictureStatus ConvertTo1BppSauvola( 
   int ImageID,
   float Factor,
   int ContrastMinDif,
   int SmoothKernel
)

Parameters

ImageID: GdPicture image identifier.
Factor: Factor of thresholding reduction. Must be a balue in tha range ]0 ; 1. Suggested value is 0.35. Higher is the factor value lighter should be the resulting image.
ContrastMinDif: This method segments the image in tiles and tries to adjust the contrast in each tiles. If the contrast in a tile is smaller than ContrastMinDif, it uses the minimum and maximum pixel values from neighbor tiles. The value must be in the range [0 - 255] and the suggested one is 50.
SmoothKernel: The half-width of the kernel used to smooth the minimum and maximum values of each tiles, in the range [0 (no smoothing) - 5]. Suggested value is 2, higer value should help to remove background parasites on poorly contrasted images.

Return Value

A member of the GdPictureStatus enumeration.

Remarks

This method requires the Image Documents component to run.

Example

Converts selected image to a 1-bit BW indexed color image, and saves result into a TIF file.

using (GdPictureImaging gdpictureImaging = new GdPictureImaging())
{
    // Open an image file. An empty string allows the control to prompt for selecting a file.
    int imageID = gdpictureImaging.CreateGdPictureImageFromFile("");
 
    gdpictureImaging.ConvertTo1BppSauvola(imageID, 0.35f, 50, 2);
    gdpictureImaging.SaveAsTIFF(imageID, "output.tif", TiffCompression.TiffCompressionAUTO);
 
    // Release used resources.
    gdpictureImaging.ReleaseGdPictureImage(imageID);
}

Reference

GdPictureImaging Class
GdPictureImaging Members
Overload List
FxBlackNWhite(Int32,BitonalReduction) Method
FxBlackNWhiteT Method
ConvertTo1Bpp(Int32) Method
ConvertTo1BppAT(Int32) Method