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Added new resize method: Lanczos. Good for most cases.

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Ilia Popov
2010-10-31 17:03:23 +01:00
parent 05e83a06bb 6b81f64adb
commit c2a0a13f4e
3 changed files with 155 additions and 7 deletions
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1
rtdata/languages/default
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@@ -651,6 +651,7 @@ TP_RESIZE_FULLSIZE;Full Image Size:
TP_RESIZE_H;H:
TP_RESIZE_HEIGHT;Height
TP_RESIZE_LABEL;Resize
TP_RESIZE_LANCZOS;Lanczos
TP_RESIZE_METHOD;Method:
TP_RESIZE_NEAREST;Nearest
TP_RESIZE_SCALE;Scale

156
rtengine/ipresize.cc
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@@ -23,6 +23,8 @@
#include <omp.h>
#endif
#include <iostream>
namespace rtengine {
#undef CLIP
@@ -33,9 +35,149 @@ namespace rtengine {
#define CLIP(a) ((a)>0?((a)<CMAXVAL?(a):CMAXVAL):0)
#define CLIPTO(a,b,c) ((a)>(b)?((a)<(c)?(a):(c)):(b))
inline double Lanc(double x, double a)
{
if (x * x < 1e-6)
return 1.0;
else if (x * x > a * a)
return 0.0;
else {
x = M_PI * x;
return sin(x) * sin(x / a) / (x * x / a);
}
}
void Lanczos(const Image16* src, Image16* dst, double scale)
{
const double delta = 1.0 / scale;
const double a = 3.0;
const double sc = std::min(scale, 1.0);
const int support = (int)(2.0 * a / sc) + 1;
// storage for precomputed parameters for horisontal interpolation
double * wwh = new double[support * dst->width];
int * jj0 = new int[dst->width];
int * jj1 = new int[dst->width];
// temporal storage for vertically-interpolated row of pixels
double * lr = new double[src->width];
double * lg = new double[src->width];
double * lb = new double[src->width];
// Phase 1: precompute coefficients for horisontal interpolation
for (int j = 0; j < dst->width; j++) {
// x coord of the center of pixel on src image
double x0 = (j + 0.5) * delta - 0.5;
// weights for interpolation in horisontal direction
double * w = wwh + j * support;
// sum of weights used for normalization
double ws = 0.0;
jj0[j] = std::max(0, (int)floor(x0 - a / sc) + 1);
jj1[j] = std::min(src->width, (int)floor(x0 + a / sc) + 1);
// calculate weights
for (int jj = jj0[j]; jj < jj1[j]; jj++) {
int k = jj - jj0[j];
double z = sc * (x0 - jj);
w[k] = Lanc(z, a);
ws += w[k];
}
// normalize weights
for (int k = 0; k < support; k++) {
w[k] /= ws;
}
}
// Phase 2: do actual interpolation
for (int i = 0; i < dst->height; i++) {
// y coord of the center of pixel on src image
double y0 = (i + 0.5) * delta - 0.5;
// weights for interpolation in y direction
double w[support];
// sum of weights used for normalization
double ws= 0.0;
int ii0 = std::max(0, (int)floor(y0 - a / sc) + 1);
int ii1 = std::min(src->height, (int)floor(y0 + a / sc) + 1);
// calculate weights for vertical interpolation
for (int ii = ii0; ii < ii1; ii++) {
int k = ii - ii0;
double z = sc * (y0 - ii);
w[k] = Lanc(z, a);
ws += w[k];
}
// normalize weights
for (int k = 0; k < support; k++) {
w[k] /= ws;
}
// Do vertical interpolation. Store results.
for (int j = 0; j < src->width; j++) {
double r = 0.0, g = 0.0, b = 0.0;
for (int ii = ii0; ii < ii1; ii++) {
int k = ii - ii0;
r += w[k] * src->r[ii][j];
g += w[k] * src->g[ii][j];
b += w[k] * src->b[ii][j];
}
lr[j] = r;
lg[j] = g;
lb[j] = b;
}
// Do horisontal interpolation
for(int j = 0; j < dst->width; j++) {
double * wh = wwh + support * j;
double r = 0.0, g = 0.0, b = 0.0;
for (int jj = jj0[j]; jj < jj1[j]; jj++) {
int k = jj - jj0[j];
r += wh[k] * lr[jj];
g += wh[k] * lg[jj];
b += wh[k] * lb[jj];
}
dst->r[i][j] = CLIP((int)r);
dst->g[i][j] = CLIP((int)g);
dst->b[i][j] = CLIP((int)b);
}
}
delete[] wwh;
delete[] jj0;
delete[] jj1;
delete[] lr;
delete[] lg;
delete[] lb;
}
void ImProcFunctions::resize (Image16* src, Image16* dst) {
if(params->resize.method == "Downscale (Better)") {
//time_t t1 = clock();
if(params->resize.method == "Lanczos") {
Lanczos(src, dst, params->resize.scale);
}
else if(params->resize.method == "Downscale (Better)") {
// small-scale algorithm by Ilia
// provides much better quality on small scales
// calculates mean value over source pixels which current destination pixel covers
@@ -117,11 +259,8 @@ void ImProcFunctions::resize (Image16* src, Image16* dst) {
dst->b[i][j] = CLIP((int)b);
}
}
return;
}
if(params->resize.method == "Downscale (Faster)")
{
else if(params->resize.method == "Downscale (Faster)") {
// faster version of algo above, does not take into account border pixels,
// which are summed with non-unity weights in slow algo. So, no need
// for weights at all
@@ -190,9 +329,8 @@ void ImProcFunctions::resize (Image16* src, Image16* dst) {
dst->b[i][j] = CLIP( b * k / divider);
}
}
return;
}
if (params->resize.method.substr(0,7)=="Bicubic") {
else if (params->resize.method.substr(0,7)=="Bicubic") {
double Av = -0.5;
if (params->resize.method=="Bicubic (Sharper)")
Av = -0.75;
@@ -290,6 +428,10 @@ void ImProcFunctions::resize (Image16* src, Image16* dst) {
}
}
}
//time_t t2 = clock();
//std::cout << "Resize: " << params->resize.method << ": "
// << (double)(t2 - t1) / CLOCKS_PER_SEC << std::endl;
}
}

5
rtgui/resize.cc
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@@ -39,6 +39,7 @@ Resize::Resize () : maxw(100000), maxh(100000) {
method->append_text (M("TP_RESIZE_BICUBICSH"));
method->append_text (M("TP_RESIZE_DOWNSCALEB"));
method->append_text (M("TP_RESIZE_DOWNSCALEF"));
method->append_text (M("TP_RESIZE_LANCZOS"));
method->set_active (0);
combos->attach (*Gtk::manage (new Gtk::Label (M("TP_RESIZE_METHOD"))), 0, 1, 0, 1, Gtk::SHRINK, Gtk::SHRINK, 2, 2);
@@ -130,6 +131,8 @@ void Resize::read (const ProcParams* pp, const ParamsEdited* pedited) {
method->set_active (5);
else if (pp->resize.method == "Downscale (Faster)")
method->set_active (6);
else if (pp->resize.method == "Lanczos")
method->set_active (7);
wDirty = false;
hDirty = false;
@@ -170,6 +173,8 @@ void Resize::write (ProcParams* pp, ParamsEdited* pedited) {
pp->resize.method = "Downscale (Better)";
else if (method->get_active_row_number() == 6)
pp->resize.method = "Downscale (Faster)";
else if (method->get_active_row_number() == 7)
pp->resize.method = "Lanczos";
pp->resize.dataspec = spec->get_active_row_number();
pp->resize.width = round (w->get_value ());