ImageGear Professional for Linux
IG_IP_median
ImageGear Professional > API Reference Guide > Core Component API Reference > Core Component Functions Reference > Image Processing Functions > IG_IP_median

This function performs a median filter on an image.

Declaration:

 
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AT_ERRCOUNT ACCUAPI IG_IP_median (
        HIGEAR hIGear, 
        const LPAT_RECT lpRect, 
        AT_DIMENSION nNeighborWidth, 
        AT_DIMENSION nNeighborHeight 
);

Arguments:

Name Type Description
hIGear HIGEAR HIGEAR handle of image.
lpRect const LPAT_RECT Far pointer to an AT_RECT struct specifying the rectangular portion of the image to operate upon. If NULL, the entire image will be operated upon. Before ImageGear performs this operation, it will check to see if an internal flag has been set to TRUE to make a mask active for this HIGEAR image. If a mask is active, and a valid pointer to a mask can be found, ImageGear will override the settings passed to this structure in favor of the non-rectangular ROI defined by the mask.
nNeighborWidth AT_DIMENSION Width of the neighborhood to include in computing each new pixel's value. Must be positive.
nNeighborHeight AT_DIMENSION Height of the neighborhood to include in computing each new pixel's value. Must be positive.

Return Value:

Returns the number of ImageGear errors that occurred during this function call.

Supported Raster Image Formats:

All pixel formats supported by ImageGear Professional, except:
Indexed RGB with non-grayscale palette.

Example:

 
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HIGEAR hIGear;    /* HIGEAR handle of image */
nErrCount        = IG_IP_median ( hIGear, NULL, 5, 5 );

Remarks:

A median filter is useful for reducing spike or snow-like noise from an image. The width and height determine the size of each original pixel's neighborhood to use to compute the median output pixels. Most applications will find that 3x3 or 5x5 works best.

Only the lpRect of the image is processed. Set lpRect = NULL to process the entire image.

This function, like other ImageGear Image Processing and Clipboard API calls, takes an AT_RECT structure as an argument, so that you can process a rectangular sub-region of an image. However, before ImageGear performs the operation specified by this function, it will check to see if an internal flag has been set to TRUE, indicating that a mask HIGEAR should be used with the image. If the flag is set to TRUE, and a valid pointer to a mask image has been assigned, ImageGear will override the settings passed to the AT_RECT structure and use the non-rectangular ROI defined by the mask HIGEAR. To create a non-rectangular region of interest, call IG_IP_NR_ROI_to_HIGEAR_mask().

Please see the descriptions of IG_IP_NR_ROI_mask_associate() and IG_IP_NR_ROI_to_HIGEAR_mask() functions for more details.

 

 

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