void
Halftone_TX::build_r_function_tex(
TEXTUREglptr r_function_map,
TEXTUREglptr source
)
{
uint* histogram_array = new uint[256 * LOD_RES];
uint sample_count = 0; //gets value from the function call below
build_pattern_histogram(histogram_array,sample_count,source);
// constructing the error correction table
if (debug)
cerr << "Halftone_TX::build_correction_tex: "
<< "Building the tone response map ... " << endl;
// forward R texture
compute_forward_R(
sample_count,
histogram_array,
&(r_function_map->image())
);
if (debug) {
r_function_map->image().write_png("test_r_function.png");
}
delete[] histogram_array;
}
void
Halftone_TX::build_correction_tex(
TEXTUREglptr correction_map,
TEXTUREglptr source
)
{
stop_watch total_timer;
// the histograms are fixed size of 256 buckets
// and there is one for each of LOD_RES LOD values
uint* histogram_array = new uint[256 * LOD_RES];
uint sample_count = 0; //gets value from the function call below
build_pattern_histogram(histogram_array,sample_count,source);
// constructing the error correction table
if (debug)
cerr << "Halftone_TX::build_correction_tex: "
<< "Building the tone response map ... " << endl;
stop_watch inv_r_timer;
// correction texture
for (int i_lod=0; i_lod<LOD_RES; i_lod++) {
//fills in a row of inverse R fot this lod value
compute_inverse_R(
i_lod,
sample_count,
histogram_array,
&(correction_map->image())
);
}
if (debug) {
cerr << " Inverse R build time : "
<< inv_r_timer.elapsed_time() << endl;
}
if (debug) {
cerr << "Total time ellapsed : "
<< total_timer.elapsed_time() << endl;
}
delete[] histogram_array;
}
void
Halftone_TX::build_pattern_histogram(
uint* histogram,
uint &sample_count,
TEXTUREglptr source
)
{
// hardcoded to 256x256 array of histograms for each lod value
assert(histogram);
stop_watch hist_timer;
if (debug) {
cerr << " Constructing histogram array ... ";
}
for (int i=0 ; i<(256*LOD_RES); i++)
histogram[i] = 0;
uint X_tex;
uint Y_tex;
if (source) {
X_tex = source->get_size()[0];
Y_tex = source->get_size()[1];
} else {
//for procedural pattern we use maximum sampling resolution
X_tex = 256;
Y_tex = 256;
}
sample_count = X_tex * Y_tex;
// building the regular histogram for each LOD value;
for (int i_lod=0; i_lod<LOD_RES; i_lod++) {
double f_lod = double(i_lod)/double(LOD_RES-1); // 0.0~1.0
for (uint x=0; x<X_tex; x++)
for (uint y=0; y<Y_tex; y++) {
double sample;
if (source) {
//sample the halftone texture
double sample_hi =
source->image().pixel_r((x*2)%X_tex, (y*2) % Y_tex);
double sample_lo =
source->image().pixel_r(x, y);
sample = min(255.0, interp(sample_lo,sample_hi,f_lod));
} else {
//sample procedural dots
double sample_hi =
procedural_dots((double(x)/double(X_tex-1)) * 2.0 ,
(double(y)/double(Y_tex-1)) * 2.0);
double sample_lo =
procedural_dots(double(x)/double(X_tex-1),
double(y)/double(Y_tex-1));
sample = min(255.0, interp(sample_lo,sample_hi,f_lod)*255.0);
}
uint bucket = uint(sample + 0.5 );
histogram[256 * i_lod + bucket]+= 1;
}
}
if (debug) {
cerr << "Histogram built time : "
<< hist_timer.elapsed_time() << endl;
}
}
