Intel® Integrated Performance Primitives (Intel® IPP) Developer Guide and Reference
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Median Filters
The median filter functions perform non-linear filtering of a source image data.
These functions use either an arbitrary rectangular mask, or the following predefined masks of the IppiMaskSize type to filter an image:
| ippMskSize3x1 | Horizontal mask of length 3 | 
| ippMskSize5x1 | Horizontal mask of length 5 | 
| ippMskSize1x3 | Vertical mask of length 3 | 
| ippMskSize3x3 | Square mask of size 3 | 
| ippMskSize1x5 | Vertical mask of length 5 | 
| ippMskSize5x5 | Square mask of size 5 | 
The size of the neighborhood and coordinates of the anchor cell in the neighborhood depend on the mask mean value. Table “Median Filter Mask, Neighborhood, and Anchor Cell” lists the mask types with the corresponding neighborhood sizes and anchor cell coordinates. Mask size in mask names is indicated in (XY) order. The anchor cell is specified by its coordinates anchor.x and anchor.y in the coordinate system associated with the upper left corner of the mask.
| Mask | Neighborhood Size | Anchor Cell | |
|---|---|---|---|
| Columns | Rows | ||
| ippMskSize3x1 | 3 | 1 | [1, 0] | 
| ippMskSize5x1 | 5 | 1 | [2, 0] | 
| ippMskSize1x3 | 1 | 3 | [0, 1] | 
| ippMskSize3x3 | 3 | 3 | [1, 1] | 
| ippMskSize1x5 | 1 | 5 | [0, 2] | 
| ippMskSize5x5 | 5 | 5 | [2, 2] | 
Median filters have the effect of removing the isolated intensity spikes and can be used to reduce noise in an image.
For details on algorithms used in Intel IPP for median filtering, see [APMF].
- FilterMedianBorderGetBufferSize
 Computes the size of the work buffer for the FilterMedianBorder function.
- FilterMedianBorder
 Performs median filtering of an image.
- FilterMedianGetBufferSize
 Computes the size of the external buffer for ippiFilterMedian function.
- FilterMedian
 Filters an image using a median filter.
- FilterMedianCross
 Filters an image using a cross median filter.
- FilterMedianWeightedCenter3x3
 Filters an image using a median filter with a weighted center pixel.
- FilterMedianColor
 Filters an image using a color median filter.