diff options
Diffstat (limited to 'jcmaster.c')
| -rw-r--r-- | jcmaster.c | 217 |
1 files changed, 198 insertions, 19 deletions
@@ -42,23 +42,172 @@ typedef my_comp_master * my_master_ptr; * Support routines that do various essential calculations. */ +/* + * Compute JPEG image dimensions and related values. + * NOTE: this is exported for possible use by application. + * Hence it mustn't do anything that can't be done twice. + */ + +GLOBAL(void) +jpeg_calc_jpeg_dimensions (j_compress_ptr cinfo) +/* Do computations that are needed before master selection phase */ +{ +#ifdef DCT_SCALING_SUPPORTED + + /* Compute actual JPEG image dimensions and DCT scaling choices. */ + if (cinfo->scale_num >= cinfo->scale_denom * 8) { + /* Provide 8/1 scaling */ + cinfo->jpeg_width = cinfo->image_width << 3; + cinfo->jpeg_height = cinfo->image_height << 3; + cinfo->min_DCT_h_scaled_size = 1; + cinfo->min_DCT_v_scaled_size = 1; + } else if (cinfo->scale_num >= cinfo->scale_denom * 4) { + /* Provide 4/1 scaling */ + cinfo->jpeg_width = cinfo->image_width << 2; + cinfo->jpeg_height = cinfo->image_height << 2; + cinfo->min_DCT_h_scaled_size = 2; + cinfo->min_DCT_v_scaled_size = 2; + } else if (cinfo->scale_num * 3 >= cinfo->scale_denom * 8) { + /* Provide 8/3 scaling */ + cinfo->jpeg_width = (cinfo->image_width << 1) + + jdiv_round_up((long) cinfo->image_width * 2, 3L); + cinfo->jpeg_height = (cinfo->image_height << 1) + + jdiv_round_up((long) cinfo->image_height * 2, 3L); + cinfo->min_DCT_h_scaled_size = 3; + cinfo->min_DCT_v_scaled_size = 3; + } else if (cinfo->scale_num >= cinfo->scale_denom * 2) { + /* Provide 2/1 scaling */ + cinfo->jpeg_width = cinfo->image_width << 1; + cinfo->jpeg_height = cinfo->image_height << 1; + cinfo->min_DCT_h_scaled_size = 4; + cinfo->min_DCT_v_scaled_size = 4; + } else if (cinfo->scale_num * 5 >= cinfo->scale_denom * 8) { + /* Provide 8/5 scaling */ + cinfo->jpeg_width = cinfo->image_width + + jdiv_round_up((long) cinfo->image_width * 3, 5L); + cinfo->jpeg_height = cinfo->image_height + + jdiv_round_up((long) cinfo->image_height * 3, 5L); + cinfo->min_DCT_h_scaled_size = 5; + cinfo->min_DCT_v_scaled_size = 5; + } else if (cinfo->scale_num * 3 >= cinfo->scale_denom * 4) { + /* Provide 4/3 scaling */ + cinfo->jpeg_width = cinfo->image_width + + jdiv_round_up((long) cinfo->image_width, 3L); + cinfo->jpeg_height = cinfo->image_height + + jdiv_round_up((long) cinfo->image_height, 3L); + cinfo->min_DCT_h_scaled_size = 6; + cinfo->min_DCT_v_scaled_size = 6; + } else if (cinfo->scale_num * 7 >= cinfo->scale_denom * 8) { + /* Provide 8/7 scaling */ + cinfo->jpeg_width = cinfo->image_width + + jdiv_round_up((long) cinfo->image_width, 7L); + cinfo->jpeg_height = cinfo->image_height + + jdiv_round_up((long) cinfo->image_height, 7L); + cinfo->min_DCT_h_scaled_size = 7; + cinfo->min_DCT_v_scaled_size = 7; + } else if (cinfo->scale_num >= cinfo->scale_denom) { + /* Provide 1/1 scaling */ + cinfo->jpeg_width = cinfo->image_width; + cinfo->jpeg_height = cinfo->image_height; + cinfo->min_DCT_h_scaled_size = DCTSIZE; + cinfo->min_DCT_v_scaled_size = DCTSIZE; + } else if (cinfo->scale_num * 9 >= cinfo->scale_denom * 8) { + /* Provide 8/9 scaling */ + cinfo->jpeg_width = (JDIMENSION) + jdiv_round_up((long) cinfo->image_width * 8, 9L); + cinfo->jpeg_height = (JDIMENSION) + jdiv_round_up((long) cinfo->image_height * 8, 9L); + cinfo->min_DCT_h_scaled_size = 9; + cinfo->min_DCT_v_scaled_size = 9; + } else if (cinfo->scale_num * 5 >= cinfo->scale_denom * 4) { + /* Provide 4/5 scaling */ + cinfo->jpeg_width = (JDIMENSION) + jdiv_round_up((long) cinfo->image_width * 4, 5L); + cinfo->jpeg_height = (JDIMENSION) + jdiv_round_up((long) cinfo->image_height * 4, 5L); + cinfo->min_DCT_h_scaled_size = 10; + cinfo->min_DCT_v_scaled_size = 10; + } else if (cinfo->scale_num * 11 >= cinfo->scale_denom * 8) { + /* Provide 8/11 scaling */ + cinfo->jpeg_width = (JDIMENSION) + jdiv_round_up((long) cinfo->image_width * 8, 11L); + cinfo->jpeg_height = (JDIMENSION) + jdiv_round_up((long) cinfo->image_height * 8, 11L); + cinfo->min_DCT_h_scaled_size = 11; + cinfo->min_DCT_v_scaled_size = 11; + } else if (cinfo->scale_num * 3 >= cinfo->scale_denom * 2) { + /* Provide 2/3 scaling */ + cinfo->jpeg_width = (JDIMENSION) + jdiv_round_up((long) cinfo->image_width * 2, 3L); + cinfo->jpeg_height = (JDIMENSION) + jdiv_round_up((long) cinfo->image_height * 2, 3L); + cinfo->min_DCT_h_scaled_size = 12; + cinfo->min_DCT_v_scaled_size = 12; + } else if (cinfo->scale_num * 13 >= cinfo->scale_denom * 8) { + /* Provide 8/13 scaling */ + cinfo->jpeg_width = (JDIMENSION) + jdiv_round_up((long) cinfo->image_width * 8, 13L); + cinfo->jpeg_height = (JDIMENSION) + jdiv_round_up((long) cinfo->image_height * 8, 13L); + cinfo->min_DCT_h_scaled_size = 13; + cinfo->min_DCT_v_scaled_size = 13; + } else if (cinfo->scale_num * 7 >= cinfo->scale_denom * 4) { + /* Provide 4/7 scaling */ + cinfo->jpeg_width = (JDIMENSION) + jdiv_round_up((long) cinfo->image_width * 4, 7L); + cinfo->jpeg_height = (JDIMENSION) + jdiv_round_up((long) cinfo->image_height * 4, 7L); + cinfo->min_DCT_h_scaled_size = 14; + cinfo->min_DCT_v_scaled_size = 14; + } else if (cinfo->scale_num * 15 >= cinfo->scale_denom * 8) { + /* Provide 8/15 scaling */ + cinfo->jpeg_width = (JDIMENSION) + jdiv_round_up((long) cinfo->image_width * 8, 15L); + cinfo->jpeg_height = (JDIMENSION) + jdiv_round_up((long) cinfo->image_height * 8, 15L); + cinfo->min_DCT_h_scaled_size = 15; + cinfo->min_DCT_v_scaled_size = 15; + } else { + /* Provide 1/2 scaling */ + cinfo->jpeg_width = (JDIMENSION) + jdiv_round_up((long) cinfo->image_width, 2L); + cinfo->jpeg_height = (JDIMENSION) + jdiv_round_up((long) cinfo->image_height, 2L); + cinfo->min_DCT_h_scaled_size = 16; + cinfo->min_DCT_v_scaled_size = 16; + } + +#else /* !DCT_SCALING_SUPPORTED */ + + /* Hardwire it to "no scaling" */ + cinfo->jpeg_width = cinfo->image_width; + cinfo->jpeg_height = cinfo->image_height; + cinfo->min_DCT_h_scaled_size = DCTSIZE; + cinfo->min_DCT_v_scaled_size = DCTSIZE; + +#endif /* DCT_SCALING_SUPPORTED */ +} + + LOCAL(void) initial_setup (j_compress_ptr cinfo) /* Do computations that are needed before master selection phase */ { - int ci; + int ci, ssize; jpeg_component_info *compptr; long samplesperrow; JDIMENSION jd_samplesperrow; + jpeg_calc_jpeg_dimensions(cinfo); + /* Sanity check on image dimensions */ - if (cinfo->image_height <= 0 || cinfo->image_width <= 0 + if (cinfo->jpeg_height <= 0 || cinfo->jpeg_width <= 0 || cinfo->num_components <= 0 || cinfo->input_components <= 0) ERREXIT(cinfo, JERR_EMPTY_IMAGE); /* Make sure image isn't bigger than I can handle */ - if ((long) cinfo->image_height > (long) JPEG_MAX_DIMENSION || - (long) cinfo->image_width > (long) JPEG_MAX_DIMENSION) + if ((long) cinfo->jpeg_height > (long) JPEG_MAX_DIMENSION || + (long) cinfo->jpeg_width > (long) JPEG_MAX_DIMENSION) ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION); /* Width of an input scanline must be representable as JDIMENSION. */ @@ -95,22 +244,52 @@ initial_setup (j_compress_ptr cinfo) ci++, compptr++) { /* Fill in the correct component_index value; don't rely on application */ compptr->component_index = ci; - /* For compression, we never do DCT scaling. */ - compptr->DCT_scaled_size = DCTSIZE; + /* In selecting the actual DCT scaling for each component, we try to + * scale down the chroma components via DCT scaling rather than downsampling. + * This saves time if the downsampler gets to use 1:1 scaling. + * Note this code adapts subsampling ratios which are powers of 2. + */ + ssize = 1; +#ifdef DCT_SCALING_SUPPORTED + while (cinfo->dct_method == JDCT_ISLOW && + cinfo->min_DCT_h_scaled_size * ssize <= DCTSIZE && + (cinfo->max_h_samp_factor % (compptr->h_samp_factor * ssize * 2)) == 0) { + ssize = ssize * 2; + } +#endif + compptr->DCT_h_scaled_size = cinfo->min_DCT_h_scaled_size * ssize; + ssize = 1; +#ifdef DCT_SCALING_SUPPORTED + while (cinfo->dct_method == JDCT_ISLOW && + cinfo->min_DCT_v_scaled_size * ssize <= DCTSIZE && + (cinfo->max_v_samp_factor % (compptr->v_samp_factor * ssize * 2)) == 0) { + ssize = ssize * 2; + } +#endif + compptr->DCT_v_scaled_size = cinfo->min_DCT_v_scaled_size * ssize; + + /* We don't support DCT ratios larger than 2. */ + if (compptr->DCT_h_scaled_size > compptr->DCT_v_scaled_size * 2) + compptr->DCT_h_scaled_size = compptr->DCT_v_scaled_size * 2; + else if (compptr->DCT_v_scaled_size > compptr->DCT_h_scaled_size * 2) + compptr->DCT_v_scaled_size = compptr->DCT_h_scaled_size * 2; + /* Size in DCT blocks */ compptr->width_in_blocks = (JDIMENSION) - jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor, + jdiv_round_up((long) cinfo->jpeg_width * (long) compptr->h_samp_factor, (long) (cinfo->max_h_samp_factor * DCTSIZE)); compptr->height_in_blocks = (JDIMENSION) - jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor, + jdiv_round_up((long) cinfo->jpeg_height * (long) compptr->v_samp_factor, (long) (cinfo->max_v_samp_factor * DCTSIZE)); /* Size in samples */ compptr->downsampled_width = (JDIMENSION) - jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor, - (long) cinfo->max_h_samp_factor); + jdiv_round_up((long) cinfo->jpeg_width * + (long) (compptr->h_samp_factor * compptr->DCT_h_scaled_size), + (long) (cinfo->max_h_samp_factor * DCTSIZE)); compptr->downsampled_height = (JDIMENSION) - jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor, - (long) cinfo->max_v_samp_factor); + jdiv_round_up((long) cinfo->jpeg_height * + (long) (compptr->v_samp_factor * compptr->DCT_v_scaled_size), + (long) (cinfo->max_v_samp_factor * DCTSIZE)); /* Mark component needed (this flag isn't actually used for compression) */ compptr->component_needed = TRUE; } @@ -119,7 +298,7 @@ initial_setup (j_compress_ptr cinfo) * main controller will call coefficient controller). */ cinfo->total_iMCU_rows = (JDIMENSION) - jdiv_round_up((long) cinfo->image_height, + jdiv_round_up((long) cinfo->jpeg_height, (long) (cinfo->max_v_samp_factor*DCTSIZE)); } @@ -325,7 +504,7 @@ per_scan_setup (j_compress_ptr cinfo) compptr->MCU_width = 1; compptr->MCU_height = 1; compptr->MCU_blocks = 1; - compptr->MCU_sample_width = DCTSIZE; + compptr->MCU_sample_width = compptr->DCT_h_scaled_size; compptr->last_col_width = 1; /* For noninterleaved scans, it is convenient to define last_row_height * as the number of block rows present in the last iMCU row. @@ -347,10 +526,10 @@ per_scan_setup (j_compress_ptr cinfo) /* Overall image size in MCUs */ cinfo->MCUs_per_row = (JDIMENSION) - jdiv_round_up((long) cinfo->image_width, + jdiv_round_up((long) cinfo->jpeg_width, (long) (cinfo->max_h_samp_factor*DCTSIZE)); cinfo->MCU_rows_in_scan = (JDIMENSION) - jdiv_round_up((long) cinfo->image_height, + jdiv_round_up((long) cinfo->jpeg_height, (long) (cinfo->max_v_samp_factor*DCTSIZE)); cinfo->blocks_in_MCU = 0; @@ -361,7 +540,7 @@ per_scan_setup (j_compress_ptr cinfo) compptr->MCU_width = compptr->h_samp_factor; compptr->MCU_height = compptr->v_samp_factor; compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height; - compptr->MCU_sample_width = compptr->MCU_width * DCTSIZE; + compptr->MCU_sample_width = compptr->MCU_width * compptr->DCT_h_scaled_size; /* Figure number of non-dummy blocks in last MCU column & row */ tmp = (int) (compptr->width_in_blocks % compptr->MCU_width); if (tmp == 0) tmp = compptr->MCU_width; @@ -433,7 +612,7 @@ prepare_for_pass (j_compress_ptr cinfo) /* Do Huffman optimization for a scan after the first one. */ select_scan_parameters(cinfo); per_scan_setup(cinfo); - if (cinfo->Ss != 0 || cinfo->Ah == 0 || cinfo->arith_code) { + if (cinfo->Ss != 0 || cinfo->Ah == 0) { (*cinfo->entropy->start_pass) (cinfo, TRUE); (*cinfo->coef->start_pass) (cinfo, JBUF_CRANK_DEST); master->pub.call_pass_startup = FALSE; @@ -567,7 +746,7 @@ jinit_c_master_control (j_compress_ptr cinfo, boolean transcode_only) cinfo->num_scans = 1; } - if (cinfo->progressive_mode) /* TEMPORARY HACK ??? */ + if (cinfo->progressive_mode && cinfo->arith_code == 0) /* TEMPORARY HACK ??? */ cinfo->optimize_coding = TRUE; /* assume default tables no good for progressive mode */ /* Initialize my private state */ |