convert disparity to depth

for(int i = 0; i < depthmap->height; i=i+1){
            for(int j = 0; j < depthmap->width; j=j+1){
                //if(cvGet2D(depthmap, i, j).val[0] > 90 && cvGet2D(depthmap, i, j).val[0] < 160){
                if(cvGet2D(depthmap, i, j).val[0] > 25){
                    float depth = 255.0*25.0/(cvGet2D(depthmap, i, j).val[0]+1);
                    //if(depth > 3) depth = 3;
                    cvSet2D(depthmap, i, j, cvScalarAll(depth));
                }
                else{
                    cvSet2D(depthmap, i, j, cvScalarAll(255));
                }
            }
        }
        cvNormalize(depthmap,depthmap,0,255,CV_MINMAX);
        cvNot(depthmap, depthmap);