image =	distanceMap2dImg (inBinImg)
image =	distanceMap2dImg (inBinImg,maxDistance)

Detailed Description

Algorithm for distance map transform computation of an input binary image.

Distance map algorithm, also called distance transform, allows to compute exact euclidian distance for each set pixel (with intensity set to 1) to the nearest boundary (nearest zero pixel) in a binary image. If the parameter $ maxDistance $ is provided, the propagation is constrained so that it stops when the distance is higher than the value.

Resulting image buffer type must be one of the following :

ipsdk::image::eImageBufferType::eIBT_UInt16
ipsdk::image::eImageBufferType::eIBT_UInt32
ipsdk::image::eImageBufferType::eIBT_Real32

Output image values are given by :

$OutDistImg[x, y] = \left\{\begin{matrix} 0 \; if \; InBinImg[x, y] = 0 \\ \min\limits_{(x', y') / InBinImg[x', y'] = 1} {norm_{2}(x, y, x', y')} \; else \end{matrix}\right.$

where $norm_{2}$ stands for euclidian norm :

$norm_{2}(x, y, x', y') = \Arrowvert \begin{pmatrix} x \\ y \end{pmatrix} - \begin{pmatrix} x' \\ y' \end{pmatrix} \Arrowvert_{2}$

Here is an example of a distance map 2d computation applied to a binary input image with an unsigned int 16 result image :

Note: A real 32 image can be used as output to avoid distance rounding approximation associated to integer output data type.

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

Example of Python code :

Example imports

import PyIPSDK

import PyIPSDK.IPSDKIPLBasicMorphology as morpho

Code Example

    # opening of input image
    inImg = PyIPSDK.loadTiffImageFile(inputImgPath)
    
    # distance map 2d computation
    outImg = morpho.distanceMap2dImg(inImg)

Example of C++ code :

Example informations

Header file

#include <IPSDKIPL/IPSDKIPLBasicMorphology/Processor/DistanceMap2dImg/DistanceMap2dImg.h>

Code Example

        // opening input image
        ImagePtr pInBinImg = loadTiffImageFile(inputImgPath);
        // define output image geometry
        ImageGeometryPtr pGeometry = geometry2d(outputImageBufferType,
                                                pInBinImg->getSizeX(),
                                                pInBinImg->getSizeY());
        // creation of output image
        boost::shared_ptr<MemoryImage> pOutDistImg(boost::make_shared<MemoryImage>());
        pOutDistImg->init(*pGeometry);
        
        // compute distance map on input image
        distanceMap2dImg(pInBinImg, pOutDistImg);