npp::ImageCPU_32f_C1 hostKernel(3,3); //allocate space for 3x3 convolution kernel

//want to set hostKernel to [-1 0 1; -1 0 1; -1 0 1]

hostKernel[0][0] = -1;   //this doesn't compile
hostKernel(0,0) = -1;    //this doesn't compile
hostKernel.at(0,0) = -1; //this doesn't compile

hostKernel.pixels(0,0)[0].x = -1;