GDCM: I'd like to do a simple sharpening filter to the image, but have no idea how to change the pixel value

Question

I'm new to GDCM(c++). What I want to do, is to code a very simple laplacian filter to the dicom image. I have gotten the buffer of the image, but what to do next? Is there a method that can let me access the pixels with coordinates as in a 2D array? After changing the pixel values, how to save the buffer to the original image?

So far im just trying to learn DICOM, so my code is actually doing nothing, but what I want to know is how to access pixel data and change it. Probably I can treat those pixels as a 2D array. My code is:

#include "gdcmPhotometricInterpretation.h"
#include <iostream>
#include "gdcmImageReader.h"
#include "gdcmImageWriter.h"
#include "gdcmBitmapToBitmapFilter.h"
#include "gdcmImageToImageFilter.h"

using namespace gdcm;
using namespace std;

int main(int argc, char *argv[]) {

    if (argc < 2) {
        std::cerr << argv[0] << " input.dcm output.dcm" << std::endl;

        return 1;
    }

    const char *filename = argv[1];       //name of read-in file
    const char *outfilename = argv[2];    //name of write-out file

    // Instanciate the image reader
    gdcm::ImageReader reader;
    reader.SetFileName(filename);
    if (!reader.Read()) {
        cerr << "Could not read: " << filename << endl;

        return 1;
    }

    const Image &image = reader.GetImage();

    //Get some properties from the image
    //Dimension of the image
    unsigned int n_dim = image.GetNumberOfDimensions();
    const unsigned int *dims = image.GetDimensions();
    //Origin
    const double *origin = image.GetOrigin();
    const PhotometricInterpretation &pl = image.GetPhotometricInterpretation();

    for (unsigned int i = 0; i < n_dim; ++i) {
        std::cout << "Dim(" << i << "): " << dims[i] << std::endl;
    }

    for (unsigned int i = 0; i < n_dim; ++i) {
        cout << "Origin(" << i << "): " << origin[i] << endl;
    }
    std::cout << "PhotometricInterpretation: " << pl << endl;

// The output of gdcm::Reader is a gdcm::File
    gdcm::File &file = reader.GetFile();

// the dataset is the the set of element we are interested in:
    gdcm::DataSet &ds = file.GetDataSet();


    const unsigned int *dimension = image.GetDimensions();
    unsigned int dimX = dimension[0];
    unsigned int dimY = dimension[1];
    PixelFormat pf = image.GetPixelFormat();
    unsigned long len = image.GetBufferLength();
    char *buffer = new char[len];

    image.GetBuffer(buffer);

    /*char * p = buffer;
    double temp;
    int ybr2[3];
    for (int r = 0; r < dimX; ++r)
        for (int g = 0; g < dimY; ++g)
             {

                ybr2[0] = r;
                ybr2[1] = g;

                //*p++ = (char) ybr2[0];
                *p++ = (char) ybr2[1];

            }*/

    DataElement pixeldata = image.GetDataElement();

    pixeldata.SetByteValue(buffer, len);
    delete[] buffer;
    SmartPointer<Image> im = image;
    im->SetDataElement(pixeldata);

    gdcm::ImageWriter WriterNew;
    //WriterNew.SetImage(image);
    WriterNew.SetImage(*im);
    WriterNew.SetFileName(outfilename);

    if (!WriterNew.Write()) {
        std::cerr << "Could not write: " << outfilename << std::endl;
        return 1;
    }

    return 0;
}

Did you solve your problem in the meantime? We would be glad to get some final, working code here - as an answer. — Trantor

elarmando elarmando · Accepted Answer · 2015-07-29T20:12:51

I think there is no method to access the array in a 2D format, but what you can do is to calculate the image position in the 1D array. For example, if x is the index of the column, and y the index of the row, the pixel color is the position y* width + x. You should also take into account the pixel size. Usually dicom images size is 2 bytes per pixel, in this case the pixel color is the position 2* (y*width + x)

GDCM: I'd like to do a simple sharpening filter to the image, but have no idea how to change the pixel value

1 Answers