git.sesse.net Git - qscale/blob - qscale.c

   1 #include <stdio.h>
   2 #include <math.h>
   3 #include <string.h>
   4 #include <stdlib.h>
   5 #include "jpeglib.h"
   6
   7 #define CACHE_LINE_FACTOR 8
   8
   9 double sinc(double x)
  10 {
  11         // This is bad for very small x, should use power series instead.
  12         if (x == 0.0)
  13                 return 1.0;
  14         else
  15                 return sin(x) / x;
  16 }
  17
  18 double lanczos_tap(double x)
  19 {
  20         if (x < -3.0 || x > 3.0)
  21                 return 0.0;
  22         if (x < 0.0)
  23                 return sinc(-x*M_PI) * sinc(-x*M_PI / 3.0);
  24         else
  25                 return sinc(x*M_PI) * sinc(x*M_PI / 3.0);
  26 }
  27
  28 struct filter {
  29         struct pix_desc *pd;
  30         float *coeffs;
  31 };
  32 struct pix_desc {
  33         unsigned start, end;
  34         unsigned startcoeff;
  35 };
  36
  37 void hscale_calc_filter(struct filter *filter, unsigned w, unsigned h, unsigned nw)
  38 {
  39         struct pix_desc *pd = (struct pix_desc *)malloc(nw * sizeof(struct pix_desc));
  40         int size_coeffs = 8;
  41         float *coeffs = (float *)malloc(size_coeffs * sizeof(float));
  42         int num_coeffs = 0;
  43         int x, sx;
  44         double sf = (double)w / (double)nw;
  45         double support = (w > nw) ? (3.0 * sf) : (3.0 / sf);
  46
  47         /* calculate the filter */
  48         for (x = 0; x < nw; ++x) {
  49                 int start = ceil(x * sf - support);
  50                 int end = floor(x * sf + support);
  51                 double sum = 0.0;
  52
  53                 if (start < 0) {
  54                         start = 0;
  55                 }
  56                 if (end > w - 1) {
  57                         end = w - 1;
  58                 }
  59
  60                 pd[x].start = start;
  61                 pd[x].end = end;
  62                 pd[x].startcoeff = num_coeffs;
  63
  64                 for (sx = start; sx <= end; ++sx) {
  65                         double nd = (w > nw) ? (sx/sf - x) : (sx - x*sf);
  66                         double f = lanczos_tap(nd);
  67                         if (num_coeffs == size_coeffs) {
  68                                 size_coeffs <<= 1;
  69                                 coeffs = (float *)realloc(coeffs, size_coeffs * sizeof(float));
  70                         }
  71
  72                         coeffs[num_coeffs++] = f;
  73                         sum += f;
  74                 }
  75
  76                 for (sx = start; sx <= end; ++sx) {
  77                         coeffs[pd[x].startcoeff + sx - start] /= sum;
  78                 }
  79         }
  80
  81         filter->pd = pd;
  82         filter->coeffs = coeffs;
  83 }
  84
  85 void hscale(struct filter *filter, unsigned char *pix, float *npix, unsigned w, unsigned h, unsigned nw, unsigned sstride, unsigned dstride)
  86 {
  87         struct pix_desc *pd = filter->pd;
  88         float *coeffs = filter->coeffs;
  89         int y;
  90
  91         for (y = 0; y < h; ++y) {
  92                 unsigned char *sptr = pix + y*sstride;
  93                 float *dptr = npix + y*dstride;
  94                 float acc = 0.0;
  95                 int x;
  96                 for (x = 0; x < nw; ++x) {
  97                         float *cf = &coeffs[pd[x].startcoeff];
  98                         unsigned sx;
  99                         acc = 0.0;
 100
 101                         for (sx = pd[x].start; sx <= pd[x].end; ++sx) {
 102                                 acc += sptr[sx] * *cf++;
 103                         }
 104                         *dptr++ = acc;
 105                 }
 106                 for ( ; x < dstride; ++x) {
 107                         *dptr++ = acc;
 108                 }
 109         }
 110 }
 111
 112 void vscale(float *pix, unsigned char *npix, unsigned w, unsigned h, unsigned nh, unsigned dstride)
 113 {
 114         struct pix_desc *pd = (struct pix_desc *)malloc(nh * sizeof(struct pix_desc));
 115         int size_coeffs = 8;
 116         float *coeffs = (float *)malloc(size_coeffs * sizeof(float));
 117         int num_coeffs = 0;
 118         int x, y, sy;
 119         double sf = (double)h / (double)nh;
 120         double support = (h > nh) ? (3.0 * sf) : (3.0 / sf);
 121
 122         /* calculate the filter */
 123         for (y = 0; y < nh; ++y) {
 124                 int start = ceil(y * sf - support);
 125                 int end = floor(y * sf + support);
 126                 double sum = 0.0;
 127
 128                 if (start < 0) {
 129                         start = 0;
 130                 }
 131                 if (end > h - 1) {
 132                         end = h - 1;
 133                 }
 134
 135                 pd[y].start = start;
 136                 pd[y].end = end;
 137                 pd[y].startcoeff = num_coeffs;
 138
 139                 for (sy = start; sy <= end; ++sy) {
 140                         double nd = (h > nh) ? (sy/sf - y) : (sy - y*sf);
 141                         double f = lanczos_tap(nd);
 142                         if (num_coeffs == size_coeffs) {
 143                                 size_coeffs <<= 1;
 144                                 coeffs = (float *)realloc(coeffs, size_coeffs * sizeof(float));
 145                         }
 146
 147                         coeffs[num_coeffs++] = f;
 148                         sum += f;
 149                 }
 150
 151                 for (sy = start; sy <= end; ++sy) {
 152                         coeffs[pd[y].startcoeff + sy - start] /= sum;
 153                 }
 154         }
 155
 156 #if CACHE_LINE_FACTOR > 1
 157         for (x = 0; x < w; x += CACHE_LINE_FACTOR) {
 158                 float *sptr = pix + x;
 159                 unsigned char *dptr = npix + x;
 160                 for (y = 0; y < nh; ++y) {
 161                         int i;
 162                         float acc[CACHE_LINE_FACTOR];
 163                         for (i = 0; i < CACHE_LINE_FACTOR; ++i)
 164                                 acc[i] = 0.0;
 165                         float *cf = &coeffs[pd[y].startcoeff];
 166                         unsigned sy;
 167
 168                         for (sy = pd[y].start; sy <= pd[y].end; ++sy) {
 169                                 for (i = 0; i < CACHE_LINE_FACTOR; ++i) {
 170                                         acc[i] += sptr[sy * w + i] * *cf;
 171                                 }
 172                                 ++cf;
 173                         }
 174
 175                         for (i = 0; i < CACHE_LINE_FACTOR; ++i) {
 176                                 unsigned char ch;
 177                                 if (acc[i] < 0.0)
 178                                         ch = 0;
 179                                 else if (acc[i] > 255.0)
 180                                         ch = 255;
 181                                 else
 182                                         ch = (unsigned char)acc[i];
 183                                 dptr[i] = ch;
 184                         }
 185                         dptr += dstride;
 186                 }
 187         }
 188         for (x = (x/CACHE_LINE_FACTOR)*CACHE_LINE_FACTOR; x < w; ++x) {
 189 #else
 190         for (x = 0; x < w; ++x) {
 191 #endif
 192                 float *sptr = pix + x;
 193                 unsigned char *dptr = npix + x;
 194                 for (y = 0; y < nh; ++y) {
 195                         float acc = 0.0;
 196                         float *cf = &coeffs[pd[y].startcoeff];
 197                         unsigned sy;
 198
 199                         for (sy = pd[y].start; sy <= pd[y].end; ++sy) {
 200                                 acc += sptr[sy * w] * *cf++;
 201                         }
 202
 203                         unsigned char ch;
 204                         if (acc < 0.0)
 205                                 ch = 0;
 206                         else if (acc > 255.0)
 207                                 ch = 255;
 208                         else
 209                                 ch = (unsigned char)acc;
 210                         *dptr = ch;
 211                         dptr += dstride;
 212                 }
 213         }
 214 }
 215
 216 int main(int argc, char **argv)
 217 {
 218         unsigned nominal_w = atoi(argv[1]);
 219         unsigned nominal_h = atoi(argv[2]);
 220
 221         unsigned samp_h0 = 2, samp_v0 = 2;
 222         unsigned samp_h1 = 1, samp_v1 = 1;
 223         unsigned samp_h2 = 1, samp_v2 = 1;
 224         unsigned max_samp_h = 2, max_samp_v = 2;
 225
 226         unsigned nw0 = nominal_w * samp_h0 / max_samp_h, nh0 = nominal_h * samp_v0 / max_samp_v;
 227         unsigned nw1 = nominal_w * samp_h1 / max_samp_h, nh1 = nominal_h * samp_v1 / max_samp_v;
 228         unsigned nw2 = nominal_w * samp_h2 / max_samp_h, nh2 = nominal_h * samp_v2 / max_samp_v;
 229
 230         unsigned stride0 = (nw0 + DCTSIZE-1) & ~(DCTSIZE-1);
 231         unsigned stride1 = (nw1 + DCTSIZE-1) & ~(DCTSIZE-1);
 232         unsigned stride2 = (nw2 + DCTSIZE-1) & ~(DCTSIZE-1);
 233
 234         struct jpeg_decompress_struct dinfo;
 235         struct jpeg_error_mgr jerr;
 236         dinfo.err = jpeg_std_error(&jerr);
 237         jpeg_create_decompress(&dinfo);
 238         jpeg_stdio_src(&dinfo, stdin);
 239         jpeg_read_header(&dinfo, TRUE);
 240         dinfo.raw_data_out = TRUE;
 241         jpeg_start_decompress(&dinfo);
 242
 243         fprintf(stderr, "Scaling using Lanczos filter:\n");
 244         fprintf(stderr, "  Y component: %ux%u -> %ux%u\n", dinfo.comp_info[0].width_in_blocks * DCTSIZE, dinfo.comp_info[0].height_in_blocks * DCTSIZE, nw0, nh0);
 245         fprintf(stderr, "  Cb component: %ux%u -> %ux%u\n", dinfo.comp_info[1].width_in_blocks * DCTSIZE, dinfo.comp_info[1].height_in_blocks * DCTSIZE, nw1, nh1);
 246         fprintf(stderr, "  Cr component: %ux%u -> %ux%u\n", dinfo.comp_info[2].width_in_blocks * DCTSIZE, dinfo.comp_info[2].height_in_blocks * DCTSIZE, nw2, nh2);
 247
 248         float *npix_y  = (float *)malloc((dinfo.comp_info[0].height_in_blocks + dinfo.comp_info[0].v_samp_factor - 1) * DCTSIZE * stride0 * sizeof(float));
 249         float *npix_cb = (float *)malloc((dinfo.comp_info[1].height_in_blocks + dinfo.comp_info[1].v_samp_factor - 1) * DCTSIZE * stride1 * sizeof(float));
 250         float *npix_cr = (float *)malloc((dinfo.comp_info[2].height_in_blocks + dinfo.comp_info[2].v_samp_factor - 1) * DCTSIZE * stride2 * sizeof(float));
 251         JSAMPLE *data_y  = (unsigned char *)malloc(nh0 * stride0);
 252         JSAMPLE *data_cb = (unsigned char *)malloc(nh1 * stride1);
 253         JSAMPLE *data_cr = (unsigned char *)malloc(nh2 * stride2);
 254
 255         struct filter filt0, filt1, filt2;
 256
 257         hscale_calc_filter(&filt0,
 258                 /* w=       */ dinfo.image_width * dinfo.comp_info[0].h_samp_factor / dinfo.max_h_samp_factor,
 259                 /* h=       */ dinfo.comp_info[0].v_samp_factor * DCTSIZE,
 260                 /* nw=      */ nw0
 261         );
 262         hscale_calc_filter(&filt1,
 263                 /* w=       */ dinfo.image_width * dinfo.comp_info[1].h_samp_factor / dinfo.max_h_samp_factor,
 264                 /* h=       */ dinfo.comp_info[1].v_samp_factor * DCTSIZE,
 265                 /* nw=      */ nw1
 266         );
 267         hscale_calc_filter(&filt2,
 268                 /* w=       */ dinfo.image_width * dinfo.comp_info[2].h_samp_factor / dinfo.max_h_samp_factor,
 269                 /* h=       */ dinfo.comp_info[2].v_samp_factor * DCTSIZE,
 270                 /* nw=      */ nw2
 271         );
 272
 273         int total_lines = 0, blocks = 0;
 274         while (total_lines < dinfo.comp_info[0].height_in_blocks * DCTSIZE) {
 275                 unsigned max_lines = dinfo.max_v_samp_factor * DCTSIZE;
 276                 JSAMPLE tmp_y [(dinfo.comp_info[0].width_in_blocks * DCTSIZE) * (DCTSIZE * dinfo.comp_info[0].v_samp_factor)];
 277                 JSAMPLE tmp_cb[(dinfo.comp_info[1].width_in_blocks * DCTSIZE) * (DCTSIZE * dinfo.comp_info[1].v_samp_factor)];
 278                 JSAMPLE tmp_cr[(dinfo.comp_info[2].width_in_blocks * DCTSIZE) * (DCTSIZE * dinfo.comp_info[2].v_samp_factor)];
 279
 280                 JSAMPROW y_row_ptrs[max_lines];
 281                 JSAMPROW cb_row_ptrs[max_lines];
 282                 JSAMPROW cr_row_ptrs[max_lines];
 283                 JSAMPROW* ptrs[] = { y_row_ptrs, cb_row_ptrs, cr_row_ptrs };
 284                 int i;
 285
 286                 for (i = 0; i < max_lines; ++i) {
 287                         y_row_ptrs[i]  = tmp_y  + i * dinfo.comp_info[0].width_in_blocks * DCTSIZE;
 288                         cb_row_ptrs[i] = tmp_cb + i * dinfo.comp_info[1].width_in_blocks * DCTSIZE;
 289                         cr_row_ptrs[i] = tmp_cr + i * dinfo.comp_info[2].width_in_blocks * DCTSIZE;
 290                 }
 291
 292                 int lines = jpeg_read_raw_data(&dinfo, ptrs, max_lines);
 293                 if (lines == 0)
 294                         break;
 295
 296                 hscale(/* filter=  */ &filt0,
 297                        /* from=    */ tmp_y,
 298                        /* to=      */ npix_y + blocks * DCTSIZE * dinfo.comp_info[0].v_samp_factor * stride0,
 299                        /* w=       */ dinfo.image_width * dinfo.comp_info[0].h_samp_factor / dinfo.max_h_samp_factor,
 300                        /* h=       */ dinfo.comp_info[0].v_samp_factor * DCTSIZE,
 301                        /* nw=      */ nw0,
 302                        /* sstride= */ dinfo.comp_info[0].width_in_blocks * DCTSIZE,
 303                        /* dstride= */ stride0);
 304
 305                 hscale(/* filter=  */ &filt1,
 306                        /* from=    */ tmp_cb,
 307                        /* to=      */ npix_cb + blocks * DCTSIZE * dinfo.comp_info[1].v_samp_factor * stride1,
 308                        /* w=       */ dinfo.image_width * dinfo.comp_info[1].h_samp_factor / dinfo.max_h_samp_factor,
 309                        /* h=       */ dinfo.comp_info[1].v_samp_factor * DCTSIZE,
 310                        /* nw=      */ nw1,
 311                        /* sstride= */ dinfo.comp_info[1].width_in_blocks * DCTSIZE,
 312                        /* dstride= */ stride1);
 313
 314                 hscale(/* filter=  */ &filt2,
 315                        /* from=    */ tmp_cr,
 316                        /* to=      */ npix_cr + blocks * DCTSIZE * dinfo.comp_info[2].v_samp_factor * stride2,
 317                        /* w=       */ dinfo.image_width * dinfo.comp_info[2].h_samp_factor / dinfo.max_h_samp_factor,
 318                        /* h=       */ dinfo.comp_info[2].v_samp_factor * DCTSIZE,
 319                        /* nw=      */ nw2,
 320                        /* sstride= */ dinfo.comp_info[2].width_in_blocks * DCTSIZE,
 321                        /* dstride= */ stride2);
 322
 323                 total_lines += max_lines;
 324                 ++blocks;
 325         }
 326
 327         vscale(npix_y,  data_y,  stride0, dinfo.image_height * dinfo.comp_info[0].v_samp_factor / dinfo.max_v_samp_factor, nh0, stride0);
 328         vscale(npix_cb, data_cb, stride1, dinfo.image_height * dinfo.comp_info[1].v_samp_factor / dinfo.max_v_samp_factor, nh1, stride1);
 329         vscale(npix_cr, data_cr, stride2, dinfo.image_height * dinfo.comp_info[2].v_samp_factor / dinfo.max_v_samp_factor, nh2, stride2);
 330         jpeg_destroy_decompress(&dinfo);
 331
 332         struct jpeg_compress_struct cinfo;
 333         cinfo.err = jpeg_std_error(&jerr);
 334         jpeg_create_compress(&cinfo);
 335         jpeg_stdio_dest(&cinfo, stdout);
 336         cinfo.input_components = 3;
 337         jpeg_set_defaults(&cinfo);
 338         jpeg_set_quality(&cinfo, 85, FALSE);
 339         cinfo.image_width = nominal_w;
 340         cinfo.image_height = nominal_h;
 341         cinfo.raw_data_in = TRUE;
 342         jpeg_set_colorspace(&cinfo, JCS_YCbCr);
 343         cinfo.comp_info[0].h_samp_factor = samp_h0;
 344         cinfo.comp_info[0].v_samp_factor = samp_v0;
 345         cinfo.comp_info[1].h_samp_factor = samp_h1;
 346         cinfo.comp_info[1].v_samp_factor = samp_v1;
 347         cinfo.comp_info[2].h_samp_factor = samp_h2;
 348         cinfo.comp_info[2].v_samp_factor = samp_v2;
 349         jpeg_start_compress(&cinfo, TRUE);
 350
 351         total_lines = 0;
 352         blocks = 0;
 353         while (total_lines < cinfo.comp_info[0].height_in_blocks * DCTSIZE) {
 354                 unsigned max_lines = cinfo.max_v_samp_factor * DCTSIZE;
 355
 356                 JSAMPROW y_row_ptrs[max_lines];
 357                 JSAMPROW cb_row_ptrs[max_lines];
 358                 JSAMPROW cr_row_ptrs[max_lines];
 359                 JSAMPROW* ptrs[] = { y_row_ptrs, cb_row_ptrs, cr_row_ptrs };
 360                 int i;
 361
 362                 for (i = 0; i < max_lines; ++i) {
 363                         // simple edge extension
 364                         int yline = i + blocks*DCTSIZE*cinfo.comp_info[0].v_samp_factor;
 365                         if (yline > nh0 - 1)
 366                                 yline = nh0 - 1;
 367
 368                         int cbline = i + blocks*DCTSIZE*cinfo.comp_info[1].v_samp_factor;
 369                         if (cbline > nh1 - 1)
 370                                 cbline = nh1 - 1;
 371
 372                         int crline = i + blocks*DCTSIZE*cinfo.comp_info[2].v_samp_factor;
 373                         if (crline > nh2 - 1)
 374                                 crline = nh2 - 1;
 375
 376                         y_row_ptrs[i]  = data_y  + yline * stride0;
 377                         cb_row_ptrs[i] = data_cb + cbline * stride1;
 378                         cr_row_ptrs[i] = data_cr + crline * stride2;
 379                 }
 380
 381                 total_lines += max_lines;
 382                 ++blocks;
 383
 384                 jpeg_write_raw_data(&cinfo, ptrs, max_lines);
 385         }
 386         jpeg_finish_compress(&cinfo);
 387         jpeg_destroy_compress(&cinfo);
 388
 389         return 0;
 390 }
 391