bilateral filter with gpu accelaration

hi everyone,

since i am very new to gpu programming, i would be glad if anyone could give me some help.

I have implemented a bilateral filter running on the CPU and wanted to change the implementation to run on a GPU, but i have no clue how to start.

void bilateralBlur(IplImage* input_img, IplImage* output_img, int sigmaS, int sigmaR)


// Create Gaussian/Bilateral filter --- mask ---

    int length = 9;

std::vector<float> mask(length);

for (int i = 0; i < length; i++)


          mask[i] =  exp(-0.5*((i*i)/(sigmaS*sigmaS)));

          //fprintf( stderr, "i = %d,  value= %f \n", i, mask[i]);


int m_width = input_img->width ;

    int m_height= input_img->height ;


    uchar* src_img= (uchar*) input_img->imageData ;

    //Ausgangs bild ist genau so groß wie das Eingangsbild!

    uchar* dst_img =(uchar*) output_img->imageData ;

double wp, k;

//evtl. mit y=-length/2; y<=m_height-length/2; y+=4

    for(int y=0; y<m_height; y+=1)


        for (int x=0; x<m_width; x+=1){

int centerPix =x + y*m_width;

for (int j=-length/2;j <=length/2;j+=1){

                for (int i=-length/2;i<=length/2;i+=1){

int curPix = x+i+(y+j)*(m_width);


                    //spatial diff

                    double delta = sqrt(i*i+j*j);

                    double euklidDiff=exp(-0.5 * pow(delta/sigmaS,2));


                    double intens = src_img-src_img[curPix];

		    double factor = exp(-0.5 * pow(intens/sigmaR,2)) * euklidDiff;

                    wp += factor * src_img[curPix];

                    k += factor;



dst_img     = wp/k;







I dont need the whole scource code but some hints. So I would really be glad i anyone could give me some tipps or code fargments.



Use a Cuda 2D-grid with size(width,height), block size 16x16 for example. This replaces the (x,y) loop.
In the kernel code process one target pixel with (i,j) loop and write the target value.

You could also use an OpenGL/Direct3D pixel shader for this.


thanks for the fast reply. I will try it out and post my results and/ or Problems.

Thanks again,