LBitmap::HighPassFilter

#include "ltwrappr.h"

L_INT LBitmap::HighPassFilter(uRadius, uOpacity)

L_UINT uRadius;	/* radius of the neighborhood*/
L_UINT uOpacity;	/* opacity */

Removes low frequency details in a bitmap, resulting in a sharpened image. This function is available in the Raster Pro and above toolkits.

Parameter	Description
uRadius	Value greater than 0 that indicates the radius of the neighborhood on which the filter is applied, in pixels.
uOpacity	Value that represents the intensity of the effect. The valid range is from 0 to 100. At 100, only the object outlines remain.

Returns

SUCCESS	The function was successful.
< 1	An error occurred. Refer to Return Codes.

Comments

This filter removes low-frequency detail in the bitmap. The effect is opposite to that of the Gaussian Blur filter (LBitmap::GaussianFilter).

To increase the thickness of the edges, increase the value of uRadius. Usually a low value for uRadius is better.

Unlike the LBitmap::UnsharpMask function, when using this function image noise is not increased.

As an example, if you use the following image:

$image\highpassfilterBefore.gif$

And you were to call LBitmap::HighPassFilter using the following settings:

Parameter	Value
uRadius	6
uOpacity	100

The following figure results:

$image\highpassfilter.gif$

If the bitmap has a region, the effect will be applied on the region only.

This function supports 12- and 16-bit grayscale and 48- and 64-bit color images. Support for 12- and 16-bit grayscale and 48- and 64-bit color images is available only in the Document/Medical toolkits.

To update a status bar or detect a user interrupt during execution of this function, refer to LBase::EnableStatusCallback.

This function does not support signed data images. It returns the error code ERROR_SIGNED_DATA_NOT_SUPPORTED if a signed data image is passed to this function.

Required DLLs and Libraries

LTIMG

For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application.

See Also

Functions:	LBitmap::Sharpen, LBitmap::Posterize, LBitmap::Mosaic, LBitmap::Emboss, LBitmap::MedianFilter, LBitmap::AddNoise, LBitmap::IntensityDetect, LBitmap::SpatialFilter, LBitmap::BinaryFilter, LBitmap::Solarize, LBitmap::WindowLevel, LBitmap::UnsharpMask, LBitmap::GaussianFilter
Topics:	Raster Image Functions: Filtering Images
	Removing Noise
	Detecting and Enhancing Edges and Lines
	Raster Image Functions: Functions Where the Region Preempts the Bitmap
	Raster Image Functions: Modifying Intensity Values
	Raster Image Functions: Removing Noise
	Raster Image Functions: Detecting and Enhancing Edges and Lines

Example

   LBitmap LeadBitmap;
   LeadBitmap.Load(TEXT("C:\\IMAGE4.CMP"), 0,ORDER_BGR);
   LeadBitmap.HighPassFilter(10, 100);