C, dengan ruang warna Lab dan dithering yang ditingkatkan
Apakah saya mengatakan saya sudah selesai? Aku berbohong. Saya pikir algoritma dalam solusi saya yang lain adalah yang terbaik di luar sana, tetapi Perl tidak cukup cepat untuk tugas-tugas angka, jadi saya menerapkan kembali pekerjaan saya di C. Sekarang menjalankan semua gambar dalam posting ini, dengan kualitas yang lebih tinggi daripada yang asli sekitar 3 menit per gambar, dan kualitas yang sedikit lebih rendah (level 0,5%) berjalan dalam 20-30 detik per gambar. Pada dasarnya semua pekerjaan dilakukan dengan ImageMagick, dan dithering dilakukan menggunakan interpolasi spline kubik ImageMagick, yang memberikan hasil yang lebih baik / kurang pola.
Kode
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <unistd.h>
#include <wand/MagickWand.h>
#define ThrowWandException(wand) \
{ \
char \
*description; \
\
ExceptionType \
severity; \
\
description=MagickGetException(wand,&severity); \
(void) fprintf(stderr,"%s %s %lu %s\n",GetMagickModule(),description); \
description=(char *) MagickRelinquishMemory(description); \
abort(); \
exit(-1); \
}
int width, height; /* Target image size */
MagickWand *source_wand, *target_wand, *img_wand, *target_lab_wand, *img_lab_wand;
PixelPacket *source_pixels, *target_pixels, *img_pixels, *target_lab_pixels, *img_lab_pixels;
Image *img, *img_lab, *target, *target_lab;
CacheView *img_lab_view, *target_lab_view;
ExceptionInfo *e;
MagickWand *load_image(const char *filename) {
MagickWand *img = NewMagickWand();
if (!MagickReadImage(img, filename)) {
ThrowWandException(img);
}
return img;
}
PixelPacket *get_pixels(MagickWand *wand) {
PixelPacket *ret = GetAuthenticPixels(
GetImageFromMagickWand(wand), 0, 0,
MagickGetImageWidth(wand), MagickGetImageHeight(wand), e);
CatchException(e);
return ret;
}
void sync_pixels(MagickWand *wand) {
SyncAuthenticPixels(GetImageFromMagickWand(wand), e);
CatchException(e);
}
MagickWand *transfer_pixels() {
if (MagickGetImageWidth(source_wand) * MagickGetImageHeight(source_wand)
!= MagickGetImageWidth(target_wand) * MagickGetImageHeight(target_wand)) {
perror("size mismtch");
}
MagickWand *img_wand = CloneMagickWand(target_wand);
img_pixels = get_pixels(img_wand);
memcpy(img_pixels, source_pixels,
MagickGetImageWidth(img_wand) * MagickGetImageHeight(img_wand) * sizeof(PixelPacket));
sync_pixels(img_wand);
return img_wand;
}
MagickWand *image_to_lab(MagickWand *img) {
MagickWand *lab = CloneMagickWand(img);
TransformImageColorspace(GetImageFromMagickWand(lab), LabColorspace);
return lab;
}
int lab_distance(PixelPacket *a, PixelPacket *b) {
int l_diff = (GetPixelL(a) - GetPixelL(b)) / 256,
a_diff = (GetPixela(a) - GetPixela(b)) / 256,
b_diff = (GetPixelb(a) - GetPixelb(b)) / 256;
return (l_diff * l_diff + a_diff * a_diff + b_diff * b_diff);
}
int should_swap(int x1, int x2, int y1, int y2) {
int dist = lab_distance(&img_lab_pixels[width * y1 + x1], &target_lab_pixels[width * y1 + x1])
+ lab_distance(&img_lab_pixels[width * y2 + x2], &target_lab_pixels[width * y2 + x2]);
int swapped_dist = lab_distance(&img_lab_pixels[width * y2 + x2], &target_lab_pixels[width * y1 + x1])
+ lab_distance(&img_lab_pixels[width * y1 + x1], &target_lab_pixels[width * y2 + x2]);
return swapped_dist < dist;
}
void pixel_multiply_add(MagickPixelPacket *dest, PixelPacket *src, double mult) {
dest->red += (double)GetPixelRed(src) * mult;
dest->green += ((double)GetPixelGreen(src) - 32768) * mult;
dest->blue += ((double)GetPixelBlue(src) - 32768) * mult;
}
#define min(x,y) (((x) < (y)) ? (x) : (y))
#define max(x,y) (((x) > (y)) ? (x) : (y))
double mpp_distance(MagickPixelPacket *a, MagickPixelPacket *b) {
double l_diff = QuantumScale * (a->red - b->red),
a_diff = QuantumScale * (a->green - b->green),
b_diff = QuantumScale * (a->blue - b->blue);
return (l_diff * l_diff + a_diff * a_diff + b_diff * b_diff);
}
void do_swap(PixelPacket *pix, int x1, int x2, int y1, int y2) {
PixelPacket tmp = pix[width * y1 + x1];
pix[width * y1 + x1] = pix[width * y2 + x2];
pix[width * y2 + x2] = tmp;
}
int should_swap_dither(double detail, int x1, int x2, int y1, int y2) {
// const InterpolatePixelMethod method = Average9InterpolatePixel;
const InterpolatePixelMethod method = SplineInterpolatePixel;
MagickPixelPacket img1, img2, img1s, img2s, target1, target2;
GetMagickPixelPacket(img, &img1);
GetMagickPixelPacket(img, &img2);
GetMagickPixelPacket(img, &img1s);
GetMagickPixelPacket(img, &img2s);
GetMagickPixelPacket(target, &target1);
GetMagickPixelPacket(target, &target2);
InterpolateMagickPixelPacket(img, img_lab_view, method, x1, y1, &img1, e);
InterpolateMagickPixelPacket(img, img_lab_view, method, x2, y2, &img2, e);
InterpolateMagickPixelPacket(target, target_lab_view, method, x1, y1, &target1, e);
InterpolateMagickPixelPacket(target, target_lab_view, method, x2, y2, &target2, e);
do_swap(img_lab_pixels, x1, x2, y1, y2);
// sync_pixels(img_wand);
InterpolateMagickPixelPacket(img, img_lab_view, method, x1, y1, &img1s, e);
InterpolateMagickPixelPacket(img, img_lab_view, method, x2, y2, &img2s, e);
do_swap(img_lab_pixels, x1, x2, y1, y2);
// sync_pixels(img_wand);
pixel_multiply_add(&img1, &img_lab_pixels[width * y1 + x1], detail);
pixel_multiply_add(&img2, &img_lab_pixels[width * y2 + x2], detail);
pixel_multiply_add(&img1s, &img_lab_pixels[width * y2 + x2], detail);
pixel_multiply_add(&img2s, &img_lab_pixels[width * y1 + x1], detail);
pixel_multiply_add(&target1, &target_lab_pixels[width * y1 + x1], detail);
pixel_multiply_add(&target2, &target_lab_pixels[width * y2 + x2], detail);
double dist = mpp_distance(&img1, &target1)
+ mpp_distance(&img2, &target2);
double swapped_dist = mpp_distance(&img1s, &target1)
+ mpp_distance(&img2s, &target2);
return swapped_dist + 1.0e-4 < dist;
}
int main(int argc, char *argv[]) {
if (argc != 7) {
fprintf(stderr, "Usage: %s source.png target.png dest nodither_pct dither_pct detail\n", argv[0]);
return 1;
}
char *source_filename = argv[1];
char *target_filename = argv[2];
char *dest = argv[3];
double nodither_pct = atof(argv[4]);
double dither_pct = atof(argv[5]);
double detail = atof(argv[6]) - 1;
const int SWAPS_PER_LOOP = 1000000;
int nodither_limit = ceil(SWAPS_PER_LOOP * nodither_pct / 100);
int dither_limit = ceil(SWAPS_PER_LOOP * dither_pct / 100);
int dither = 0, frame = 0;
char outfile[256], cmdline[1024];
sprintf(outfile, "out/%s.png", dest);
MagickWandGenesis();
e = AcquireExceptionInfo();
source_wand = load_image(source_filename);
source_pixels = get_pixels(source_wand);
target_wand = load_image(target_filename);
target_pixels = get_pixels(target_wand);
img_wand = transfer_pixels();
img_pixels = get_pixels(img_wand);
target_lab_wand = image_to_lab(target_wand);
target_lab_pixels = get_pixels(target_lab_wand);
img_lab_wand = image_to_lab(img_wand);
img_lab_pixels = get_pixels(img_lab_wand);
img = GetImageFromMagickWand(img_lab_wand);
target = GetImageFromMagickWand(target_lab_wand);
img_lab_view = AcquireAuthenticCacheView(img, e);
target_lab_view = AcquireAuthenticCacheView(target,e);
CatchException(e);
width = MagickGetImageWidth(img_wand);
height = MagickGetImageHeight(img_wand);
while (1) {
int swaps_made = 0;
for (int n = 0 ; n < SWAPS_PER_LOOP ; n++) {
int x1 = rand() % width,
x2 = rand() % width,
y1 = rand() % height,
y2 = rand() % height;
int swap = dither ?
should_swap_dither(detail, x1, x2, y1, y2)
: should_swap(x1, x2, y1, y2);
if (swap) {
do_swap(img_pixels, x1, x2, y1, y2);
do_swap(img_lab_pixels, x1, x2, y1, y2);
swaps_made ++;
}
}
sync_pixels(img_wand);
if (!MagickWriteImages(img_wand, outfile, MagickTrue)) {
ThrowWandException(img_wand);
}
img_pixels = get_pixels(img_wand);
sprintf(cmdline, "cp out/%s.png anim/%s/%05i.png", dest, dest, frame++);
system(cmdline);
if (!dither && swaps_made < nodither_limit) {
sprintf(cmdline, "cp out/%s.png out/%s-nodither.png", dest, dest);
system(cmdline);
dither = 1;
} else if (dither && swaps_made < dither_limit)
break;
}
return 0;
}
Kompilasi dengan
gcc -std=gnu99 -O3 -march=native -ffast-math \
-o transfer `pkg-config --cflags MagickWand` \
transfer.c `pkg-config --libs MagickWand` -lm
Hasil
Sebagian besar sama dengan versi Perl, hanya sedikit lebih baik, tetapi ada beberapa pengecualian. Dithering kurang terlihat secara umum. Scream -> Starry Night tidak memiliki efek "flaming mountain", dan Camaro terlihat kurang gemerlap dengan piksel abu-abu. Saya pikir kode colorspace versi Perl memiliki bug dengan piksel saturasi rendah.
Palet Gothic Amerika
Palet Mona Lisa
Palet Starry Night
Palet teriakan
Palet bola
Mustang (palet Camaro)
Camaro (palet Mustang)