bool =	median2dImg_allow8bitsCompression (inImg,inHalfKnlSizeX,inHalfKnlSizeY,outImg)
image =	median2dImg (inImg,inHalfKnlSizeX,inHalfKnlSizeY)

Detailed Description

Median filter on a 2d image.

The median filter is a non-linear filter used to reduce impulsive noise in an image while preserving edges.

The median filter computes, for each pixel of input image, the median of its neighbouring pixels.

On output image values are given by:

$OutImg[x, y] = median(\left\lbrace InImg(x+o_x, y+o_y), -n_x \leq o_x \leq n_x, -n_y \leq o_y \leq n_y\rbrace\right)$

where :

function applied to a set of cardinal ( is an odd positive integer) returns the element of the collection $[p_i, 1 \leq i \leq n]$ containing the elements of the set sorted by increasing value
is defined by InHalfKnlSizeX attribute
is defined by InHalfKnlSizeY attribute

Input and output images must have same size.

The algorithm is optimized if at least one of the following conditions is satisfied:

$max_{InImg} - min_{InImg} \leq 255$ and input image pixels are encoded on integers
the kernel is a square of size 3 (in other words, and )
the kernel is a square of size 5 (in other words, and )

If none of the previous conditions are satisfied, the user has all the same the possibility to execute a fast 2d median filter, by setting the attribute "InOutOptAllow8bitsCompression" to value true (this attribute is set to false by default). In this case, he will get a resulting image that will be an approximation of a real median (the resulting image will contain a maximum of 256 different grey level values).

Here are 2 examples of a median filter operation applied to a noised 8-bits grey levels input image:

with :

with :

See also: http://en.wikipedia.org/wiki/Median_filter

Example of Python code :

Example imports

import PyIPSDK

import PyIPSDK.IPSDKIPLFiltering as filter

Code Example

    # opening of input images
    inImg = PyIPSDK.loadTiffImageFile(inputImgPath)
    
    # median filter 2d computation
    outImg = filter.median2dImg(inImg, 3, 3)

Example of C++ code :

Example informations

Header file

#include <IPSDKIPL/IPSDKIPLFiltering/Processor/Median2dImg/Median2dImg.h>

Code Example

    // opening input image
    ImagePtr pInImg = loadTiffImageFile(inputImgPath);
    if(pInImg->getBufferType() != imageBufferType)
            pInImg = util::convertImg(pInImg, imageBufferType);
    // compute median on input image
    ImagePtr pOutImg = median2dImg(pInImg, inHalfKnlSizeX, inHalfKnlSizeY);