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| 1 /* | |
| 2 * jcsample.c | |
| 3 * | |
| 4 * Copyright (C) 1991-1996, Thomas G. Lane. | |
| 5 * This file is part of the Independent JPEG Group's software. | |
| 6 * For conditions of distribution and use, see the accompanying README file. | |
| 7 * | |
| 8 * This file contains downsampling routines. | |
| 9 * | |
| 10 * Downsampling input data is counted in "row groups". A row group | |
| 11 * is defined to be max_v_samp_factor pixel rows of each component, | |
| 12 * from which the downsampler produces v_samp_factor sample rows. | |
| 13 * A single row group is processed in each call to the downsampler module. | |
| 14 * | |
| 15 * The downsampler is responsible for edge-expansion of its output data | |
| 16 * to fill an integral number of DCT blocks horizontally. The source buffer | |
| 17 * may be modified if it is helpful for this purpose (the source buffer is | |
| 18 * allocated wide enough to correspond to the desired output width). | |
| 19 * The caller (the prep controller) is responsible for vertical padding. | |
| 20 * | |
| 21 * The downsampler may request "context rows" by setting need_context_rows | |
| 22 * during startup. In this case, the input arrays will contain at least | |
| 23 * one row group's worth of pixels above and below the passed-in data; | |
| 24 * the caller will create dummy rows at image top and bottom by replicating | |
| 25 * the first or last real pixel row. | |
| 26 * | |
| 27 * An excellent reference for image resampling is | |
| 28 * Digital Image Warping, George Wolberg, 1990. | |
| 29 * Pub. by IEEE Computer Society Press, Los Alamitos, CA. ISBN 0-8186-8944-7. | |
| 30 * | |
| 31 * The downsampling algorithm used here is a simple average of the source | |
| 32 * pixels covered by the output pixel. The hi-falutin sampling literature | |
| 33 * refers to this as a "box filter". In general the characteristics of a box | |
| 34 * filter are not very good, but for the specific cases we normally use (1:1 | |
| 35 * and 2:1 ratios) the box is equivalent to a "triangle filter" which is not | |
| 36 * nearly so bad. If you intend to use other sampling ratios, you'd be well | |
| 37 * advised to improve this code. | |
| 38 * | |
| 39 * A simple input-smoothing capability is provided. This is mainly intended | |
| 40 * for cleaning up color-dithered GIF input files (if you find it inadequate, | |
| 41 * we suggest using an external filtering program such as pnmconvol). When | |
| 42 * enabled, each input pixel P is replaced by a weighted sum of itself and its | |
| 43 * eight neighbors. P's weight is 1-8*SF and each neighbor's weight is SF, | |
| 44 * where SF = (smoothing_factor / 1024). | |
| 45 * Currently, smoothing is only supported for 2h2v sampling factors. | |
| 46 */ | |
| 47 | |
| 48 #define JPEG_INTERNALS | |
| 49 #include "jinclude.h" | |
| 50 #include "jpeglib.h" | |
| 51 | |
| 52 | |
| 53 /* Pointer to routine to downsample a single component */ | |
| 54 typedef JMETHOD(void, downsample1_ptr, | |
| 55 (j_compress_ptr cinfo, jpeg_component_info * compptr, | |
| 56 JSAMPARRAY input_data, JSAMPARRAY output_data)); | |
| 57 | |
| 58 /* Private subobject */ | |
| 59 | |
| 60 typedef struct { | |
| 61 struct jpeg_downsampler pub; /* public fields */ | |
| 62 | |
| 63 /* Downsampling method pointers, one per component */ | |
| 64 downsample1_ptr methods[MAX_COMPONENTS]; | |
| 65 } my_downsampler; | |
| 66 | |
| 67 typedef my_downsampler * my_downsample_ptr; | |
| 68 | |
| 69 | |
| 70 /* | |
| 71 * Initialize for a downsampling pass. | |
| 72 */ | |
| 73 | |
| 74 METHODDEF(void) | |
| 75 start_pass_downsample (j_compress_ptr cinfo) | |
| 76 { | |
| 77 /* no work for now */ | |
| 78 } | |
| 79 | |
| 80 | |
| 81 /* | |
| 82 * Expand a component horizontally from width input_cols to width output_cols, | |
| 83 * by duplicating the rightmost samples. | |
| 84 */ | |
| 85 | |
| 86 LOCAL(void) | |
| 87 expand_right_edge (JSAMPARRAY image_data, int num_rows, | |
| 88 JDIMENSION input_cols, JDIMENSION output_cols) | |
| 89 { | |
| 90 register JSAMPROW ptr; | |
| 91 register JSAMPLE pixval; | |
| 92 register int count; | |
| 93 int row; | |
| 94 int numcols = (int) (output_cols - input_cols); | |
| 95 | |
| 96 if (numcols > 0) { | |
| 97 for (row = 0; row < num_rows; row++) { | |
| 98 ptr = image_data[row] + input_cols; | |
| 99 pixval = ptr[-1]; /* don't need GETJSAMPLE() here */ | |
| 100 for (count = numcols; count > 0; count--) | |
| 101 *ptr++ = pixval; | |
| 102 } | |
| 103 } | |
| 104 } | |
| 105 | |
| 106 | |
| 107 /* | |
| 108 * Do downsampling for a whole row group (all components). | |
| 109 * | |
| 110 * In this version we simply downsample each component independently. | |
| 111 */ | |
| 112 | |
| 113 METHODDEF(void) | |
| 114 sep_downsample (j_compress_ptr cinfo, | |
| 115 JSAMPIMAGE input_buf, JDIMENSION in_row_index, | |
| 116 JSAMPIMAGE output_buf, JDIMENSION out_row_group_index) | |
| 117 { | |
| 118 my_downsample_ptr downsample = (my_downsample_ptr) cinfo->downsample; | |
| 119 int ci; | |
| 120 jpeg_component_info * compptr; | |
| 121 JSAMPARRAY in_ptr, out_ptr; | |
| 122 | |
| 123 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; | |
| 124 ci++, compptr++) { | |
| 125 in_ptr = input_buf[ci] + in_row_index; | |
| 126 out_ptr = output_buf[ci] + (out_row_group_index * compptr->v_samp_factor); | |
| 127 (*downsample->methods[ci]) (cinfo, compptr, in_ptr, out_ptr); | |
| 128 } | |
| 129 } | |
| 130 | |
| 131 | |
| 132 /* | |
| 133 * Downsample pixel values of a single component. | |
| 134 * One row group is processed per call. | |
| 135 * This version handles arbitrary integral sampling ratios, without smoothing. | |
| 136 * Note that this version is not actually used for customary sampling ratios. | |
| 137 */ | |
| 138 | |
| 139 METHODDEF(void) | |
| 140 int_downsample (j_compress_ptr cinfo, jpeg_component_info * compptr, | |
| 141 JSAMPARRAY input_data, JSAMPARRAY output_data) | |
| 142 { | |
| 143 int inrow, outrow, h_expand, v_expand, numpix, numpix2, h, v; | |
| 144 JDIMENSION outcol, outcol_h; /* outcol_h == outcol*h_expand */ | |
| 145 JDIMENSION output_cols = compptr->width_in_blocks * DCTSIZE; | |
| 146 JSAMPROW inptr, outptr; | |
| 147 INT32 outvalue; | |
| 148 | |
| 149 h_expand = cinfo->max_h_samp_factor / compptr->h_samp_factor; | |
| 150 v_expand = cinfo->max_v_samp_factor / compptr->v_samp_factor; | |
| 151 numpix = h_expand * v_expand; | |
| 152 numpix2 = numpix/2; | |
| 153 | |
| 154 /* Expand input data enough to let all the output samples be generated | |
| 155 * by the standard loop. Special-casing padded output would be more | |
| 156 * efficient. | |
| 157 */ | |
| 158 expand_right_edge(input_data, cinfo->max_v_samp_factor, | |
| 159 cinfo->image_width, output_cols * h_expand); | |
| 160 | |
| 161 inrow = 0; | |
| 162 for (outrow = 0; outrow < compptr->v_samp_factor; outrow++) { | |
| 163 outptr = output_data[outrow]; | |
| 164 for (outcol = 0, outcol_h = 0; outcol < output_cols; | |
| 165 outcol++, outcol_h += h_expand) { | |
| 166 outvalue = 0; | |
| 167 for (v = 0; v < v_expand; v++) { | |
| 168 inptr = input_data[inrow+v] + outcol_h; | |
| 169 for (h = 0; h < h_expand; h++) { | |
| 170 outvalue += (INT32) GETJSAMPLE(*inptr++); | |
| 171 } | |
| 172 } | |
| 173 *outptr++ = (JSAMPLE) ((outvalue + numpix2) / numpix); | |
| 174 } | |
| 175 inrow += v_expand; | |
| 176 } | |
| 177 } | |
| 178 | |
| 179 | |
| 180 /* | |
| 181 * Downsample pixel values of a single component. | |
| 182 * This version handles the special case of a full-size component, | |
| 183 * without smoothing. | |
| 184 */ | |
| 185 | |
| 186 METHODDEF(void) | |
| 187 fullsize_downsample (j_compress_ptr cinfo, jpeg_component_info * compptr, | |
| 188 JSAMPARRAY input_data, JSAMPARRAY output_data) | |
| 189 { | |
| 190 /* Copy the data */ | |
| 191 jcopy_sample_rows(input_data, 0, output_data, 0, | |
| 192 cinfo->max_v_samp_factor, cinfo->image_width); | |
| 193 /* Edge-expand */ | |
| 194 expand_right_edge(output_data, cinfo->max_v_samp_factor, | |
| 195 cinfo->image_width, compptr->width_in_blocks * DCTSIZE); | |
| 196 } | |
| 197 | |
| 198 | |
| 199 /* | |
| 200 * Downsample pixel values of a single component. | |
| 201 * This version handles the common case of 2:1 horizontal and 1:1 vertical, | |
| 202 * without smoothing. | |
| 203 * | |
| 204 * A note about the "bias" calculations: when rounding fractional values to | |
| 205 * integer, we do not want to always round 0.5 up to the next integer. | |
| 206 * If we did that, we'd introduce a noticeable bias towards larger values. | |
| 207 * Instead, this code is arranged so that 0.5 will be rounded up or down at | |
| 208 * alternate pixel locations (a simple ordered dither pattern). | |
| 209 */ | |
| 210 | |
| 211 METHODDEF(void) | |
| 212 h2v1_downsample (j_compress_ptr cinfo, jpeg_component_info * compptr, | |
| 213 JSAMPARRAY input_data, JSAMPARRAY output_data) | |
| 214 { | |
| 215 int outrow; | |
| 216 JDIMENSION outcol; | |
| 217 JDIMENSION output_cols = compptr->width_in_blocks * DCTSIZE; | |
| 218 register JSAMPROW inptr, outptr; | |
| 219 register int bias; | |
| 220 | |
| 221 /* Expand input data enough to let all the output samples be generated | |
| 222 * by the standard loop. Special-casing padded output would be more | |
| 223 * efficient. | |
| 224 */ | |
| 225 expand_right_edge(input_data, cinfo->max_v_samp_factor, | |
| 226 cinfo->image_width, output_cols * 2); | |
| 227 | |
| 228 for (outrow = 0; outrow < compptr->v_samp_factor; outrow++) { | |
| 229 outptr = output_data[outrow]; | |
| 230 inptr = input_data[outrow]; | |
| 231 bias = 0; /* bias = 0,1,0,1,... for successive samples */ | |
| 232 for (outcol = 0; outcol < output_cols; outcol++) { | |
| 233 *outptr++ = (JSAMPLE) ((GETJSAMPLE(*inptr) + GETJSAMPLE(inptr[1]) | |
| 234 + bias) >> 1); | |
| 235 bias ^= 1; /* 0=>1, 1=>0 */ | |
| 236 inptr += 2; | |
| 237 } | |
| 238 } | |
| 239 } | |
| 240 | |
| 241 | |
| 242 /* | |
| 243 * Downsample pixel values of a single component. | |
| 244 * This version handles the standard case of 2:1 horizontal and 2:1 vertical, | |
| 245 * without smoothing. | |
| 246 */ | |
| 247 | |
| 248 METHODDEF(void) | |
| 249 h2v2_downsample (j_compress_ptr cinfo, jpeg_component_info * compptr, | |
| 250 JSAMPARRAY input_data, JSAMPARRAY output_data) | |
| 251 { | |
| 252 int inrow, outrow; | |
| 253 JDIMENSION outcol; | |
| 254 JDIMENSION output_cols = compptr->width_in_blocks * DCTSIZE; | |
| 255 register JSAMPROW inptr0, inptr1, outptr; | |
| 256 register int bias; | |
| 257 | |
| 258 /* Expand input data enough to let all the output samples be generated | |
| 259 * by the standard loop. Special-casing padded output would be more | |
| 260 * efficient. | |
| 261 */ | |
| 262 expand_right_edge(input_data, cinfo->max_v_samp_factor, | |
| 263 cinfo->image_width, output_cols * 2); | |
| 264 | |
| 265 inrow = 0; | |
| 266 for (outrow = 0; outrow < compptr->v_samp_factor; outrow++) { | |
| 267 outptr = output_data[outrow]; | |
| 268 inptr0 = input_data[inrow]; | |
| 269 inptr1 = input_data[inrow+1]; | |
| 270 bias = 1; /* bias = 1,2,1,2,... for successive samples */ | |
| 271 for (outcol = 0; outcol < output_cols; outcol++) { | |
| 272 *outptr++ = (JSAMPLE) ((GETJSAMPLE(*inptr0) + GETJSAMPLE(inptr0[1]) + | |
| 273 GETJSAMPLE(*inptr1) + GETJSAMPLE(inptr1[1]) | |
| 274 + bias) >> 2); | |
| 275 bias ^= 3; /* 1=>2, 2=>1 */ | |
| 276 inptr0 += 2; inptr1 += 2; | |
| 277 } | |
| 278 inrow += 2; | |
| 279 } | |
| 280 } | |
| 281 | |
| 282 | |
| 283 #ifdef INPUT_SMOOTHING_SUPPORTED | |
| 284 | |
| 285 /* | |
| 286 * Downsample pixel values of a single component. | |
| 287 * This version handles the standard case of 2:1 horizontal and 2:1 vertical, | |
| 288 * with smoothing. One row of context is required. | |
| 289 */ | |
| 290 | |
| 291 METHODDEF(void) | |
| 292 h2v2_smooth_downsample (j_compress_ptr cinfo, jpeg_component_info * compptr, | |
| 293 JSAMPARRAY input_data, JSAMPARRAY output_data) | |
| 294 { | |
| 295 int inrow, outrow; | |
| 296 JDIMENSION colctr; | |
| 297 JDIMENSION output_cols = compptr->width_in_blocks * DCTSIZE; | |
| 298 register JSAMPROW inptr0, inptr1, above_ptr, below_ptr, outptr; | |
| 299 INT32 membersum, neighsum, memberscale, neighscale; | |
| 300 | |
| 301 /* Expand input data enough to let all the output samples be generated | |
| 302 * by the standard loop. Special-casing padded output would be more | |
| 303 * efficient. | |
| 304 */ | |
| 305 expand_right_edge(input_data - 1, cinfo->max_v_samp_factor + 2, | |
| 306 cinfo->image_width, output_cols * 2); | |
| 307 | |
| 308 /* We don't bother to form the individual "smoothed" input pixel values; | |
| 309 * we can directly compute the output which is the average of the four | |
| 310 * smoothed values. Each of the four member pixels contributes a fraction | |
| 311 * (1-8*SF) to its own smoothed image and a fraction SF to each of the three | |
| 312 * other smoothed pixels, therefore a total fraction (1-5*SF)/4 to the final | |
| 313 * output. The four corner-adjacent neighbor pixels contribute a fraction | |
| 314 * SF to just one smoothed pixel, or SF/4 to the final output; while the | |
| 315 * eight edge-adjacent neighbors contribute SF to each of two smoothed | |
| 316 * pixels, or SF/2 overall. In order to use integer arithmetic, these | |
| 317 * factors are scaled by 2^16 = 65536. | |
| 318 * Also recall that SF = smoothing_factor / 1024. | |
| 319 */ | |
| 320 | |
| 321 memberscale = 16384 - cinfo->smoothing_factor * 80; /* scaled (1-5*SF)/4 */ | |
| 322 neighscale = cinfo->smoothing_factor * 16; /* scaled SF/4 */ | |
| 323 | |
| 324 inrow = 0; | |
| 325 for (outrow = 0; outrow < compptr->v_samp_factor; outrow++) { | |
| 326 outptr = output_data[outrow]; | |
| 327 inptr0 = input_data[inrow]; | |
| 328 inptr1 = input_data[inrow+1]; | |
| 329 above_ptr = input_data[inrow-1]; | |
| 330 below_ptr = input_data[inrow+2]; | |
| 331 | |
| 332 /* Special case for first column: pretend column -1 is same as column 0 */ | |
| 333 membersum = GETJSAMPLE(*inptr0) + GETJSAMPLE(inptr0[1]) + | |
| 334 GETJSAMPLE(*inptr1) + GETJSAMPLE(inptr1[1]); | |
| 335 neighsum = GETJSAMPLE(*above_ptr) + GETJSAMPLE(above_ptr[1]) + | |
| 336 GETJSAMPLE(*below_ptr) + GETJSAMPLE(below_ptr[1]) + | |
| 337 GETJSAMPLE(*inptr0) + GETJSAMPLE(inptr0[2]) + | |
| 338 GETJSAMPLE(*inptr1) + GETJSAMPLE(inptr1[2]); | |
| 339 neighsum += neighsum; | |
| 340 neighsum += GETJSAMPLE(*above_ptr) + GETJSAMPLE(above_ptr[2]) + | |
| 341 GETJSAMPLE(*below_ptr) + GETJSAMPLE(below_ptr[2]); | |
| 342 membersum = membersum * memberscale + neighsum * neighscale; | |
| 343 *outptr++ = (JSAMPLE) ((membersum + 32768) >> 16); | |
| 344 inptr0 += 2; inptr1 += 2; above_ptr += 2; below_ptr += 2; | |
| 345 | |
| 346 for (colctr = output_cols - 2; colctr > 0; colctr--) { | |
| 347 /* sum of pixels directly mapped to this output element */ | |
| 348 membersum = GETJSAMPLE(*inptr0) + GETJSAMPLE(inptr0[1]) + | |
| 349 GETJSAMPLE(*inptr1) + GETJSAMPLE(inptr1[1]); | |
| 350 /* sum of edge-neighbor pixels */ | |
| 351 neighsum = GETJSAMPLE(*above_ptr) + GETJSAMPLE(above_ptr[1]) + | |
| 352 GETJSAMPLE(*below_ptr) + GETJSAMPLE(below_ptr[1]) + | |
| 353 GETJSAMPLE(inptr0[-1]) + GETJSAMPLE(inptr0[2]) + | |
| 354 GETJSAMPLE(inptr1[-1]) + GETJSAMPLE(inptr1[2]); | |
| 355 /* The edge-neighbors count twice as much as corner-neighbors */ | |
| 356 neighsum += neighsum; | |
| 357 /* Add in the corner-neighbors */ | |
| 358 neighsum += GETJSAMPLE(above_ptr[-1]) + GETJSAMPLE(above_ptr[2]) + | |
| 359 GETJSAMPLE(below_ptr[-1]) + GETJSAMPLE(below_ptr[2]); | |
| 360 /* form final output scaled up by 2^16 */ | |
| 361 membersum = membersum * memberscale + neighsum * neighscale; | |
| 362 /* round, descale and output it */ | |
| 363 *outptr++ = (JSAMPLE) ((membersum + 32768) >> 16); | |
| 364 inptr0 += 2; inptr1 += 2; above_ptr += 2; below_ptr += 2; | |
| 365 } | |
| 366 | |
| 367 /* Special case for last column */ | |
| 368 membersum = GETJSAMPLE(*inptr0) + GETJSAMPLE(inptr0[1]) + | |
| 369 GETJSAMPLE(*inptr1) + GETJSAMPLE(inptr1[1]); | |
| 370 neighsum = GETJSAMPLE(*above_ptr) + GETJSAMPLE(above_ptr[1]) + | |
| 371 GETJSAMPLE(*below_ptr) + GETJSAMPLE(below_ptr[1]) + | |
| 372 GETJSAMPLE(inptr0[-1]) + GETJSAMPLE(inptr0[1]) + | |
| 373 GETJSAMPLE(inptr1[-1]) + GETJSAMPLE(inptr1[1]); | |
| 374 neighsum += neighsum; | |
| 375 neighsum += GETJSAMPLE(above_ptr[-1]) + GETJSAMPLE(above_ptr[1]) + | |
| 376 GETJSAMPLE(below_ptr[-1]) + GETJSAMPLE(below_ptr[1]); | |
| 377 membersum = membersum * memberscale + neighsum * neighscale; | |
| 378 *outptr = (JSAMPLE) ((membersum + 32768) >> 16); | |
| 379 | |
| 380 inrow += 2; | |
| 381 } | |
| 382 } | |
| 383 | |
| 384 | |
| 385 /* | |
| 386 * Downsample pixel values of a single component. | |
| 387 * This version handles the special case of a full-size component, | |
| 388 * with smoothing. One row of context is required. | |
| 389 */ | |
| 390 | |
| 391 METHODDEF(void) | |
| 392 fullsize_smooth_downsample (j_compress_ptr cinfo, jpeg_component_info *compptr, | |
| 393 JSAMPARRAY input_data, JSAMPARRAY output_data) | |
| 394 { | |
| 395 int outrow; | |
| 396 JDIMENSION colctr; | |
| 397 JDIMENSION output_cols = compptr->width_in_blocks * DCTSIZE; | |
| 398 register JSAMPROW inptr, above_ptr, below_ptr, outptr; | |
| 399 INT32 membersum, neighsum, memberscale, neighscale; | |
| 400 int colsum, lastcolsum, nextcolsum; | |
| 401 | |
| 402 /* Expand input data enough to let all the output samples be generated | |
| 403 * by the standard loop. Special-casing padded output would be more | |
| 404 * efficient. | |
| 405 */ | |
| 406 expand_right_edge(input_data - 1, cinfo->max_v_samp_factor + 2, | |
| 407 cinfo->image_width, output_cols); | |
| 408 | |
| 409 /* Each of the eight neighbor pixels contributes a fraction SF to the | |
| 410 * smoothed pixel, while the main pixel contributes (1-8*SF). In order | |
| 411 * to use integer arithmetic, these factors are multiplied by 2^16 = 65536. | |
| 412 * Also recall that SF = smoothing_factor / 1024. | |
| 413 */ | |
| 414 | |
| 415 memberscale = 65536L - cinfo->smoothing_factor * 512L; /* scaled 1-8*SF */ | |
| 416 neighscale = cinfo->smoothing_factor * 64; /* scaled SF */ | |
| 417 | |
| 418 for (outrow = 0; outrow < compptr->v_samp_factor; outrow++) { | |
| 419 outptr = output_data[outrow]; | |
| 420 inptr = input_data[outrow]; | |
| 421 above_ptr = input_data[outrow-1]; | |
| 422 below_ptr = input_data[outrow+1]; | |
| 423 | |
| 424 /* Special case for first column */ | |
| 425 colsum = GETJSAMPLE(*above_ptr++) + GETJSAMPLE(*below_ptr++) + | |
| 426 GETJSAMPLE(*inptr); | |
| 427 membersum = GETJSAMPLE(*inptr++); | |
| 428 nextcolsum = GETJSAMPLE(*above_ptr) + GETJSAMPLE(*below_ptr) + | |
| 429 GETJSAMPLE(*inptr); | |
| 430 neighsum = colsum + (colsum - membersum) + nextcolsum; | |
| 431 membersum = membersum * memberscale + neighsum * neighscale; | |
| 432 *outptr++ = (JSAMPLE) ((membersum + 32768) >> 16); | |
| 433 lastcolsum = colsum; colsum = nextcolsum; | |
| 434 | |
| 435 for (colctr = output_cols - 2; colctr > 0; colctr--) { | |
| 436 membersum = GETJSAMPLE(*inptr++); | |
| 437 above_ptr++; below_ptr++; | |
| 438 nextcolsum = GETJSAMPLE(*above_ptr) + GETJSAMPLE(*below_ptr) + | |
| 439 GETJSAMPLE(*inptr); | |
| 440 neighsum = lastcolsum + (colsum - membersum) + nextcolsum; | |
| 441 membersum = membersum * memberscale + neighsum * neighscale; | |
| 442 *outptr++ = (JSAMPLE) ((membersum + 32768) >> 16); | |
| 443 lastcolsum = colsum; colsum = nextcolsum; | |
| 444 } | |
| 445 | |
| 446 /* Special case for last column */ | |
| 447 membersum = GETJSAMPLE(*inptr); | |
| 448 neighsum = lastcolsum + (colsum - membersum) + colsum; | |
| 449 membersum = membersum * memberscale + neighsum * neighscale; | |
| 450 *outptr = (JSAMPLE) ((membersum + 32768) >> 16); | |
| 451 | |
| 452 } | |
| 453 } | |
| 454 | |
| 455 #endif /* INPUT_SMOOTHING_SUPPORTED */ | |
| 456 | |
| 457 | |
| 458 /* | |
| 459 * Module initialization routine for downsampling. | |
| 460 * Note that we must select a routine for each component. | |
| 461 */ | |
| 462 | |
| 463 GLOBAL(void) | |
| 464 jinit_downsampler (j_compress_ptr cinfo) | |
| 465 { | |
| 466 my_downsample_ptr downsample; | |
| 467 int ci; | |
| 468 jpeg_component_info * compptr; | |
| 469 boolean smoothok = TRUE; | |
| 470 | |
| 471 downsample = (my_downsample_ptr) | |
| 472 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
| 473 SIZEOF(my_downsampler)); | |
| 474 cinfo->downsample = (struct jpeg_downsampler *) downsample; | |
| 475 downsample->pub.start_pass = start_pass_downsample; | |
| 476 downsample->pub.downsample = sep_downsample; | |
| 477 downsample->pub.need_context_rows = FALSE; | |
| 478 | |
| 479 if (cinfo->CCIR601_sampling) | |
| 480 ERREXIT(cinfo, JERR_CCIR601_NOTIMPL); | |
| 481 | |
| 482 /* Verify we can handle the sampling factors, and set up method pointers */ | |
| 483 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; | |
| 484 ci++, compptr++) { | |
| 485 if (compptr->h_samp_factor == cinfo->max_h_samp_factor && | |
| 486 compptr->v_samp_factor == cinfo->max_v_samp_factor) { | |
| 487 #ifdef INPUT_SMOOTHING_SUPPORTED | |
| 488 if (cinfo->smoothing_factor) { | |
| 489 downsample->methods[ci] = fullsize_smooth_downsample; | |
| 490 downsample->pub.need_context_rows = TRUE; | |
| 491 } else | |
| 492 #endif | |
| 493 downsample->methods[ci] = fullsize_downsample; | |
| 494 } else if (compptr->h_samp_factor * 2 == cinfo->max_h_samp_factor && | |
| 495 compptr->v_samp_factor == cinfo->max_v_samp_factor) { | |
| 496 smoothok = FALSE; | |
| 497 downsample->methods[ci] = h2v1_downsample; | |
| 498 } else if (compptr->h_samp_factor * 2 == cinfo->max_h_samp_factor && | |
| 499 compptr->v_samp_factor * 2 == cinfo->max_v_samp_factor) { | |
| 500 #ifdef INPUT_SMOOTHING_SUPPORTED | |
| 501 if (cinfo->smoothing_factor) { | |
| 502 downsample->methods[ci] = h2v2_smooth_downsample; | |
| 503 downsample->pub.need_context_rows = TRUE; | |
| 504 } else | |
| 505 #endif | |
| 506 downsample->methods[ci] = h2v2_downsample; | |
| 507 } else if ((cinfo->max_h_samp_factor % compptr->h_samp_factor) == 0 && | |
| 508 (cinfo->max_v_samp_factor % compptr->v_samp_factor) == 0) { | |
| 509 smoothok = FALSE; | |
| 510 downsample->methods[ci] = int_downsample; | |
| 511 } else | |
| 512 ERREXIT(cinfo, JERR_FRACT_SAMPLE_NOTIMPL); | |
| 513 } | |
| 514 | |
| 515 #ifdef INPUT_SMOOTHING_SUPPORTED | |
| 516 if (cinfo->smoothing_factor && !smoothok) | |
| 517 TRACEMS(cinfo, 0, JTRC_SMOOTH_NOTIMPL); | |
| 518 #endif | |
| 519 } | |
| OLD | NEW |
|---|
Chromium Code Reviews
Issue 1705523002:
Remove libjpeg and libjpeg_turbo. (Closed)
Base URL: https://github.com/domokit/mojo.git@master