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
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