FilterContraHarmonicMean  Method

Description         This function will filter the image by the nonlinear contra-harmonic mean method. This function works for only monochrome, 8 bit per pixel and 24 bit per pixel images. The contra-harmonic mean filter is member of a set of nonlinear mean filters, which are better at removing Gaussian type noise and preserving edge features than the arithmetic mean filter. The contra-harmonic filter is very good at removing positive outliers for negative values of P and negative outliers for positive values of P. The definition of contra-harmonic filter is:

where the coordinate (x+i, y+j ) is defined over the image A and the coordinate (i j) is defined over the N x N size square mask.

Examples

Description: Gauss                             Description: contra

Syntax                 RetVal = [BiFilter.]FilterContraHarmonicMean  hDib N P iShowProgress hWnd

Returns               RetVal                    LONGLONG The handle of new filtered DIB, 0 if an error occurred, or -1 if the BIFilter.dll does not installed.

Remarks             hDib                       LONGLONG Handle of the image to filter.

                            N                             short                This parameter specifies the size of the square mask. N cannot be less than 1. See the description and examples above for further information and a possible value.

                            P                             short                This parameter specifies the value P in the equation above. See the description and examples above for further information and a possible value.

                            iShowProgress       short                This parameter specifies the displaying of the progressbar and the preview dialog.

Available values:

DISPLAY_NONE (0) - The progressbar and the preview dialog will not display before filtering.

DISPLAY_PROGRESS (1) - The progressbar will display during filtering procedure.

DISPLAY_DIALOG (2) - The preview dialog will display before filtering. This dialog shows the part of the image before and after filtering.

DISPLAY_BOTH (3) - The progressbar and the preview dialog will display.

IMPORTANT: The preview dialog will only display, if there is BIDlgs32.dll installed.

                            hWnd                     LONGLONG Handler of the parent window.

See Also