/* * jcdeflts.c * * Copyright (C) 1991, 1992, Thomas G. Lane. * This file is part of the Independent JPEG Group's software. * For conditions of distribution and use, see the accompanying README file. * * This file contains optional default-setting code for the JPEG compressor. * User interfaces do not have to use this file, but those that don't use it * must know a lot more about the innards of the JPEG code. */ #include "jinclude.h" /* Default do-nothing progress monitoring routine. * This can be overridden by a user interface that wishes to * provide progress monitoring; just set methods->progress_monitor * after j_c_defaults is done. The routine will be called periodically * during the compression process. * * During any one pass, loopcounter increases from 0 up to (not including) * looplimit; the step size is not necessarily 1. Both the step size and * the limit may differ between passes. The expected total number of passes * is in cinfo->total_passes, and the number of passes already completed is * in cinfo->completed_passes. Thus the fraction of work completed may be * estimated as * completed_passes + (loopcounter/looplimit) * ------------------------------------------ * total_passes * ignoring the fact that the passes may not be equal amounts of work. */ METHODDEF void progress_monitor (compress_info_ptr cinfo, long loopcounter, long looplimit) { /* do nothing */ } /* * Table setup routines */ LOCAL void add_huff_table (compress_info_ptr cinfo, HUFF_TBL **htblptr, const UINT8 *bits, const UINT8 *val) /* Define a Huffman table */ { if (*htblptr == NULL) *htblptr = (HUFF_TBL *) (*cinfo->emethods->alloc_small) (SIZEOF(HUFF_TBL)); memcpy((void *) (*htblptr)->bits, (const void *) bits, SIZEOF((*htblptr)->bits)); memcpy((void *) (*htblptr)->huffval, (const void *) val, SIZEOF((*htblptr)->huffval)); /* Initialize sent_table FALSE so table will be written to JPEG file. * In an application where we are writing non-interchange JPEG files, * it might be desirable to save space by leaving default Huffman tables * out of the file. To do that, just initialize sent_table = TRUE... */ (*htblptr)->sent_table = FALSE; } LOCAL void std_huff_tables (compress_info_ptr cinfo) /* Set up the standard Huffman tables (cf. JPEG standard section K.3) */ /* IMPORTANT: these are only valid for 8-bit data precision! */ { static const UINT8 dc_luminance_bits[17] = { /* 0-base */ 0, 0, 1, 5, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0 }; static const UINT8 dc_luminance_val[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 }; static const UINT8 dc_chrominance_bits[17] = { /* 0-base */ 0, 0, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0 }; static const UINT8 dc_chrominance_val[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 }; static const UINT8 ac_luminance_bits[17] = { /* 0-base */ 0, 0, 2, 1, 3, 3, 2, 4, 3, 5, 5, 4, 4, 0, 0, 1, 0x7d }; static const UINT8 ac_luminance_val[] = { 0x01, 0x02, 0x03, 0x00, 0x04, 0x11, 0x05, 0x12, 0x21, 0x31, 0x41, 0x06, 0x13, 0x51, 0x61, 0x07, 0x22, 0x71, 0x14, 0x32, 0x81, 0x91, 0xa1, 0x08, 0x23, 0x42, 0xb1, 0xc1, 0x15, 0x52, 0xd1, 0xf0, 0x24, 0x33, 0x62, 0x72, 0x82, 0x09, 0x0a, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7a, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8a, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8, 0xf9, 0xfa }; static const UINT8 ac_chrominance_bits[17] = { /* 0-base */ 0, 0, 2, 1, 2, 4, 4, 3, 4, 7, 5, 4, 4, 0, 1, 2, 0x77 }; static const UINT8 ac_chrominance_val[] = { 0x00, 0x01, 0x02, 0x03, 0x11, 0x04, 0x05, 0x21, 0x31, 0x06, 0x12, 0x41, 0x51, 0x07, 0x61, 0x71, 0x13, 0x22, 0x32, 0x81, 0x08, 0x14, 0x42, 0x91, 0xa1, 0xb1, 0xc1, 0x09, 0x23, 0x33, 0x52, 0xf0, 0x15, 0x62, 0x72, 0xd1, 0x0a, 0x16, 0x24, 0x34, 0xe1, 0x25, 0xf1, 0x17, 0x18, 0x19, 0x1a, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7a, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8a, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8, 0xf9, 0xfa }; add_huff_table(cinfo, &cinfo->dc_huff_tbl_ptrs[0], dc_luminance_bits, dc_luminance_val); add_huff_table(cinfo, &cinfo->ac_huff_tbl_ptrs[0], ac_luminance_bits, ac_luminance_val); add_huff_table(cinfo, &cinfo->dc_huff_tbl_ptrs[1], dc_chrominance_bits, dc_chrominance_val); add_huff_table(cinfo, &cinfo->ac_huff_tbl_ptrs[1], ac_chrominance_bits, ac_chrominance_val); } /* This is the sample quantization table given in the JPEG spec section K.1, * but expressed in zigzag order (as are all of our quant. tables). * The spec says that the values given produce "good" quality, and * when divided by 2, "very good" quality. (These two settings are * selected by quality=50 and quality=75 in j_set_quality, below.) */ static const QUANT_VAL std_luminance_quant_tbl[DCTSIZE2] = { 16, 11, 12, 14, 12, 10, 16, 14, 13, 14, 18, 17, 16, 19, 24, 40, 26, 24, 22, 22, 24, 49, 35, 37, 29, 40, 58, 51, 61, 60, 57, 51, 56, 55, 64, 72, 92, 78, 64, 68, 87, 69, 55, 56, 80, 109, 81, 87, 95, 98, 103, 104, 103, 62, 77, 113, 121, 112, 100, 120, 92, 101, 103, 99 }; static const QUANT_VAL std_chrominance_quant_tbl[DCTSIZE2] = { 17, 18, 18, 24, 21, 24, 47, 26, 26, 47, 99, 66, 56, 66, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99 }; LOCAL void add_quant_table (compress_info_ptr cinfo, int which_tbl, const QUANT_VAL *basic_table, int scale_factor, boolean force_baseline) /* Define a quantization table equal to the basic_table times */ /* a scale factor (given as a percentage) */ { QUANT_TBL_PTR * qtblptr = & cinfo->quant_tbl_ptrs[which_tbl]; int i; long temp; if (*qtblptr == NULL) *qtblptr = (QUANT_TBL_PTR) (*cinfo->emethods->alloc_small) (SIZEOF(QUANT_TBL)); for (i = 0; i < DCTSIZE2; i++) { temp = ((long) basic_table[i] * scale_factor + 50L) / 100L; /* limit the values to the valid range */ if (temp <= 0L) temp = 1L; #ifdef EIGHT_BIT_SAMPLES if (temp > 32767L) temp = 32767L; /* QUANT_VALs are 'short' */ #else if (temp > 65535L) temp = 65535L; /* QUANT_VALs are 'UINT16' */ #endif if (force_baseline && temp > 255L) temp = 255L; /* limit to baseline range if requested */ (*qtblptr)[i] = (QUANT_VAL) temp; } } GLOBAL void j_set_quality (compress_info_ptr cinfo, int quality, boolean force_baseline) /* Set or change the 'quality' (quantization) setting. */ /* The 'quality' factor should be 0 (terrible) to 100 (very good). */ /* Quality 50 corresponds to the JPEG basic tables given above; */ /* quality 100 results in no quantization scaling at all. */ /* If force_baseline is TRUE, quantization table entries are limited */ /* to 0..255 for JPEG baseline compatibility; this is only an issue */ /* for quality settings below 24. */ { /* Safety limit on quality factor. Convert 0 to 1 to avoid zero divide. */ if (quality <= 0) quality = 1; if (quality > 100) quality = 100; /* Convert quality rating to a percentage scaling of the basic tables. * The basic table is used as-is (scaling 100) for a quality of 50. * Qualities 50..100 are converted to scaling percentage 200 - 2*Q; * note that at Q=100 the scaling is 0, which will cause add_quant_table * to make all the table entries 1 (hence, no quantization loss). * Qualities 1..50 are converted to scaling percentage 5000/Q. */ if (quality < 50) quality = 5000 / quality; else quality = 200 - quality*2; /* Set up two quantization tables using the specified quality scaling */ add_quant_table(cinfo, 0, std_luminance_quant_tbl, quality, force_baseline); add_quant_table(cinfo, 1, std_chrominance_quant_tbl, quality, force_baseline); } /* Default parameter setup for compression. * * User interfaces that don't choose to use this routine must do their * own setup of all these parameters. Alternately, you can call this * to establish defaults and then alter parameters selectively. This * is the recommended approach since, if we add any new parameters, * your code will still work (they'll be set to reasonable defaults). * * See above for the meaning of the 'quality' and 'force_baseline' parameters. * Typically, the application's default quality setting will be passed to this * routine. A later call on j_set_quality() can be used to change to a * user-specified quality setting. * * This routine sets up for a color image; to output a grayscale image, * do this first and call j_monochrome_default() afterwards. * (The latter can be called within c_ui_method_selection, so the * choice can depend on the input file header.) * Note that if you want a JPEG colorspace other than GRAYSCALE or YCbCr, * you should also change the component ID codes, and you should NOT emit * a JFIF header (set write_JFIF_header = FALSE). * * CAUTION: if you want to compress multiple images per run, it's necessary * to call j_c_defaults before *each* call to jpeg_compress, since subsidiary * structures like the Huffman tables are automatically freed during cleanup. */ GLOBAL void j_c_defaults (compress_info_ptr cinfo, int quality, boolean force_baseline) /* NB: the external methods must already be set up. */ { short i; jpeg_component_info * compptr; /* Initialize pointers as needed to mark stuff unallocated. */ cinfo->comp_info = NULL; for (i = 0; i < NUM_QUANT_TBLS; i++) cinfo->quant_tbl_ptrs[i] = NULL; for (i = 0; i < NUM_HUFF_TBLS; i++) { cinfo->dc_huff_tbl_ptrs[i] = NULL; cinfo->ac_huff_tbl_ptrs[i] = NULL; } cinfo->data_precision = BITS_IN_JSAMPLE; /* default; can be overridden by input_init */ cinfo->density_unit = 0; /* Pixel size is unknown by default */ cinfo->X_density = 1; /* Pixel aspect ratio is square by default */ cinfo->Y_density = 1; cinfo->input_gamma = 1.0; /* no gamma correction by default */ /* Prepare three color components; first is luminance which is also usable */ /* for grayscale. The others are assumed to be UV or similar chrominance. */ cinfo->write_JFIF_header = TRUE; cinfo->jpeg_color_space = CS_YCbCr; cinfo->num_components = 3; cinfo->comp_info = (jpeg_component_info *) (*cinfo->emethods->alloc_small) (4 * SIZEOF(jpeg_component_info)); /* Note: we allocate a 4-entry comp_info array so that user interface can * easily change over to CMYK color space if desired. */ compptr = &cinfo->comp_info[0]; compptr->component_index = 0; compptr->component_id = 1; /* JFIF specifies IDs 1,2,3 */ compptr->h_samp_factor = 2; /* default to 2x2 subsamples of chrominance */ compptr->v_samp_factor = 2; compptr->quant_tbl_no = 0; /* use tables 0 for luminance */ compptr->dc_tbl_no = 0; compptr->ac_tbl_no = 0; compptr = &cinfo->comp_info[1]; compptr->component_index = 1; compptr->component_id = 2; compptr->h_samp_factor = 1; compptr->v_samp_factor = 1; compptr->quant_tbl_no = 1; /* use tables 1 for chrominance */ compptr->dc_tbl_no = 1; compptr->ac_tbl_no = 1; compptr = &cinfo->comp_info[2]; compptr->component_index = 2; compptr->component_id = 3; compptr->h_samp_factor = 1; compptr->v_samp_factor = 1; compptr->quant_tbl_no = 1; /* use tables 1 for chrominance */ compptr->dc_tbl_no = 1; compptr->ac_tbl_no = 1; /* Set up two quantization tables using the specified quality scaling */ j_set_quality(cinfo, quality, force_baseline); /* Set up two Huffman tables in case user interface wants Huffman coding */ std_huff_tables(cinfo); /* Initialize default arithmetic coding conditioning */ for (i = 0; i < NUM_ARITH_TBLS; i++) { cinfo->arith_dc_L[i] = 0; cinfo->arith_dc_U[i] = 1; cinfo->arith_ac_K[i] = 5; } /* Use Huffman coding, not arithmetic coding, by default */ cinfo->arith_code = FALSE; /* Color images are interleaved by default */ cinfo->interleave = TRUE; /* By default, don't do extra passes to optimize entropy coding */ cinfo->optimize_coding = FALSE; /* By default, use the simpler non-cosited sampling alignment */ cinfo->CCIR601_sampling = FALSE; /* No restart markers */ cinfo->restart_interval = 0; /* Install default do-nothing progress monitoring method. */ cinfo->methods->progress_monitor = progress_monitor; } GLOBAL void j_monochrome_default (compress_info_ptr cinfo) /* Change the j_c_defaults() values to emit a monochrome JPEG file. */ { jpeg_component_info * compptr; cinfo->jpeg_color_space = CS_GRAYSCALE; cinfo->num_components = 1; /* Set single component to 1x1 subsampling */ compptr = &cinfo->comp_info[0]; compptr->h_samp_factor = 1; compptr->v_samp_factor = 1; }