text: /*
   * jcparam.c
   *
   * Copyright (C) 1991-1998, 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.
   * Applications 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.
   */
  
  #define JPEG_INTERNALS
  #include "jinclude.h"
  #include "jpeglib.h"
  
  
  /*
   * Quantization table setup routines
   */
  
  GLOBAL(void)
  jpeg_add_quant_table (j_compress_ptr cinfo, int which_tbl,
  		      const unsigned int *basic_table,
  		      int scale_factor, wxjpeg_boolean force_baseline)
  /* Define a quantization table equal to the basic_table times
   * a scale factor (given as a percentage).
   * If force_baseline is TRUE, the computed quantization table entries
   * are limited to 1..255 for JPEG baseline compatibility.
   */
  {
    JQUANT_TBL ** qtblptr;
    int i;
    long temp;
  
    /* Safety check to ensure start_compress not called yet. */
    if (cinfo->global_state != CSTATE_START)
      ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
  
    if (which_tbl < 0 || which_tbl >= NUM_QUANT_TBLS)
      ERREXIT1(cinfo, JERR_DQT_INDEX, which_tbl);
  
    qtblptr = & cinfo->quant_tbl_ptrs[which_tbl];
  
    if (*qtblptr == NULL)
      *qtblptr = jpeg_alloc_quant_table((j_common_ptr) cinfo);
  
    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;
      if (temp > 32767L) temp = 32767L; /* max quantizer needed for 12 bits */
      if (force_baseline && temp > 255L)
        temp = 255L;		/* limit to baseline range if requested */
      (*qtblptr)->quantval[i] = (UINT16) temp;
    }
  
    /* Initialize sent_table FALSE so table will be written to JPEG file. */
    (*qtblptr)->sent_table = FALSE;
  }
  
  
  GLOBAL(void)
  jpeg_set_linear_quality (j_compress_ptr cinfo, int scale_factor,
  			 wxjpeg_boolean force_baseline)
  /* Set or change the 'quality' (quantization) setting, using default tables
   * and a straight percentage-scaling quality scale.  In most cases it's better
   * to use jpeg_set_quality (below); this entry point is provided for
   * applications that insist on a linear percentage scaling.
   */
  {
    /* These are the sample quantization tables given in JPEG spec section K.1.
     * The spec says that the values given produce "good" quality, and
     * when divided by 2, "very good" quality.
     */
    static const unsigned int std_luminance_quant_tbl[DCTSIZE2] = {
      16,  11,  10,  16,  24,  40,  51,  61,
      12,  12,  14,  19,  26,  58,  60,  55,
      14,  13,  16,  24,  40,  57,  69,  56,
      14,  17,  22,  29,  51,  87,  80,  62,
      18,  22,  37,  56,  68, 109, 103,  77,
      24,  35,  55,  64,  81, 104, 113,  92,
      49,  64,  78,  87, 103, 121, 120, 101,
      72,  92,  95,  98, 112, 100, 103,  99
    };
    static const unsigned int std_chrominance_quant_tbl[DCTSIZE2] = {
      17,  18,  24,  47,  99,  99,  99,  99,
      18,  21,  26,  66,  99,  99,  99,  99,
      24,  26,  56,  99,  99,  99,  99,  99,
      47,  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
    };
  
    /* Set up two quantization tables using the specified scaling */
    jpeg_add_quant_table(cinfo, 0, std_luminance_quant_tbl,
  		       scale_factor, force_baseline);
    jpeg_add_quant_table(cinfo, 1, std_chrominance_quant_tbl,
  		       scale_factor, force_baseline);
  }
  
  
  GLOBAL(int)
  jpeg_quality_scaling (int quality)
  /* Convert a user-specified quality rating to a percentage scaling factor
   * for an underlying quantization table, using our recommended scaling curve.
   * The input 'quality' factor should be 0 (terrible) to 100 (very good).
   */
  {
    /* Safety limit on quality factor.  Convert 0 to 1 to avoid zero divide. */
    if (quality <= 0) quality = 1;
    if (quality > 100) quality = 100;
  
    /* 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 jpeg_add_quant_table
     * to make all the table entries 1 (hence, minimum quantization loss).
     * Qualities 1..50 are converted to scaling percentage 5000/Q.
     */
    if (quality < 50)
      quality = 5000 / quality;
    else
      quality = 200 - quality*2;
  
    return quality;
  }
  
  
  GLOBAL(void)
  jpeg_set_quality (j_compress_ptr cinfo, int quality, wxjpeg_boolean force_baseline)
  /* Set or change the 'quality' (quantization) setting, using default tables.
   * This is the standard quality-adjusting entry point for typical user
   * interfaces; only those who want detailed control over quantization tables
   * would use the preceding three routines directly.
   */
  {
    /* Convert user 0-100 rating to percentage scaling */
    quality = jpeg_quality_scaling(quality);
  
    /* Set up standard quality tables */
    jpeg_set_linear_quality(cinfo, quality, force_baseline);
  }
  
  
  /*
   * Huffman table setup routines
   */
  
  LOCAL(void)
  add_huff_table (j_compress_ptr cinfo,
  		JHUFF_TBL **htblptr, const UINT8 *bits, const UINT8 *val)
  /* Define a Huffman table */
  {
    int nsymbols, len;
  
    if (*htblptr == NULL)
      *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo);
  
    /* Copy the number-of-symbols-of-each-code-length counts */
    MEMCOPY((*htblptr)->bits, bits, SIZEOF((*htblptr)->bits));
  
    /* Validate the counts.  We do this here mainly so we can copy the right
     * number of symbols from the val[] array, without risking marching off
     * the end of memory.  jchuff.c will do a more thorough test later.
     */
    nsymbols = 0;
    for (len = 1; len <= 16; len++)
      nsymbols += bits[len];
    if (nsymbols < 1 || nsymbols > 256)
      ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
  
    MEMCOPY((*htblptr)->huffval, val, nsymbols * SIZEOF(UINT8));
  
    /* Initialize sent_table FALSE so table will be written to JPEG file. */
    (*htblptr)->sent_table = FALSE;
  }
  
  
  LOCAL(void)
  std_huff_tables (j_compress_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 bits_dc_luminance[17] =
      { /* 0-base */ 0, 0, 1, 5, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0 };
    static const UINT8 val_dc_luminance[] =
      { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 };
    
    static const UINT8 bits_dc_chrominance[17] =
      { /* 0-base */ 0, 0, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0 };
    static const UINT8 val_dc_chrominance[] =
      { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 };
    
    static const UINT8 bits_ac_luminance[17] =
      { /* 0-base */ 0, 0, 2, 1, 3, 3, 2, 4, 3, 5, 5, 4, 4, 0, 0, 1, 0x7d };
    static const UINT8 val_ac_luminance[] =
      { 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 bits_ac_chrominance[17] =
      { /* 0-base */ 0, 0, 2, 1, 2, 4, 4, 3, 4, 7, 5, 4, 4, 0, 1, 2, 0x77 };
    static const UINT8 val_ac_chrominance[] =
      { 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],
  		 bits_dc_luminance, val_dc_luminance);
    add_huff_table(cinfo, &cinfo->ac_huff_tbl_ptrs[0],
  		 bits_ac_luminance, val_ac_luminance);
    add_huff_table(cinfo, &cinfo->dc_huff_tbl_ptrs[1],
  		 bits_dc_chrominance, val_dc_chrominance);
    add_huff_table(cinfo, &cinfo->ac_huff_tbl_ptrs[1],
  		 bits_ac_chrominance, val_ac_chrominance);
  }
  
  
  /*
   * Default parameter setup for compression.
   *
   * Applications 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).
   */
  
  GLOBAL(void)
  jpeg_set_defaults (j_compress_ptr cinfo)
  {
    int i;
  
    /* Safety check to ensure start_compress not called yet. */
    if (cinfo->global_state != CSTATE_START)
      ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
  
    /* Allocate comp_info array large enough for maximum component count.
     * Array is made permanent in case application wants to compress
     * multiple images at same param settings.
     */
    if (cinfo->comp_info == NULL)
      cinfo->comp_info = (jpeg_component_info *)
        (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
  				  MAX_COMPONENTS * SIZEOF(jpeg_component_info));
  
    /* Initialize everything not dependent on the color space */
  
    cinfo->data_precision = BITS_IN_JSAMPLE;
    /* Set up two quantization tables using default quality of 75 */
    jpeg_set_quality(cinfo, 75, TRUE);
    /* Set up two Huffman tables */
    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;
    }
  
    /* Default is no multiple-scan output */
    cinfo->scan_info = NULL;
    cinfo->num_scans = 0;
  
    /* Expect normal source image, not raw downsampled data */
    cinfo->raw_data_in = FALSE;
  
    /* Use Huffman coding, not arithmetic coding, by default */
    cinfo->arith_code = FALSE;
  
    /* By default, don't do extra passes to optimize entropy coding */
    cinfo->optimize_coding = FALSE;
    /* The standard Huffman tables are only valid for 8-bit data precision.
     * If the precision is higher, force optimization on so that usable
     * tables will be computed.  This test can be removed if default tables
     * are supplied that are valid for the desired precision.
     */
    if (cinfo->data_precision > 8)
      cinfo->optimize_coding = TRUE;
  
    /* By default, use the simpler non-cosited sampling alignment */
    cinfo->CCIR601_sampling = FALSE;
  
    /* No input smoothing */
    cinfo->smoothing_factor = 0;
  
    /* DCT algorithm preference */
    cinfo->dct_method = JDCT_DEFAULT;
  
    /* No restart markers */
    cinfo->restart_interval = 0;
    cinfo->restart_in_rows = 0;
  
    /* Fill in default JFIF marker parameters.  Note that whether the marker
     * will actually be written is determined by jpeg_set_colorspace.
     *
     * By default, the library emits JFIF version code 1.01.
     * An application that wants to emit JFIF 1.02 extension markers should set
     * JFIF_minor_version to 2.  We could probably get away with just defaulting
     * to 1.02, but there may still be some decoders in use that will complain
     * about that; saying 1.01 should minimize compatibility problems.
     */
    cinfo->JFIF_major_version = 1; /* Default JFIF version = 1.01 */
    cinfo->JFIF_minor_version = 1;
    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;
  
    /* Choose JPEG colorspace based on input space, set defaults accordingly */
  
    jpeg_default_colorspace(cinfo);
  }
  
  
  /*
   * Select an appropriate JPEG colorspace for in_color_space.
   */
  
  GLOBAL(void)
  jpeg_default_colorspace (j_compress_ptr cinfo)
  {
    switch (cinfo->in_color_space) {
    case JCS_GRAYSCALE:
      jpeg_set_colorspace(cinfo, JCS_GRAYSCALE);
      break;
    case JCS_RGB:
      jpeg_set_colorspace(cinfo, JCS_YCbCr);
      break;
    case JCS_YCbCr:
      jpeg_set_colorspace(cinfo, JCS_YCbCr);
      break;
    case JCS_CMYK:
      jpeg_set_colorspace(cinfo, JCS_CMYK); /* By default, no translation */
      break;
    case JCS_YCCK:
      jpeg_set_colorspace(cinfo, JCS_YCCK);
      break;
    case JCS_UNKNOWN:
      jpeg_set_colorspace(cinfo, JCS_UNKNOWN);
      break;
    default:
      ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
    }
  }
  
  
  /*
   * Set the JPEG colorspace, and choose colorspace-dependent default values.
   */
  
  GLOBAL(void)
  jpeg_set_colorspace (j_compress_ptr cinfo, J_COLOR_SPACE colorspace)
  {
    jpeg_component_info * compptr;
    int ci;
  
  #define SET_COMP(index,id,hsamp,vsamp,quant,dctbl,actbl)  \
    (compptr = &cinfo->comp_info[index], \
     compptr->component_id = (id), \
     compptr->h_samp_factor = (hsamp), \
     compptr->v_samp_factor = (vsamp), \
     compptr->quant_tbl_no = (quant), \
     compptr->dc_tbl_no = (dctbl), \
     compptr->ac_tbl_no = (actbl) )
  
    /* Safety check to ensure start_compress not called yet. */
    if (cinfo->global_state != CSTATE_START)
      ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
  
    /* For all colorspaces, we use Q and Huff tables 0 for luminance components,
     * tables 1 for chrominance components.
     */
  
    cinfo->jpeg_color_space = colorspace;
  
    cinfo->write_JFIF_header = FALSE; /* No marker for non-JFIF colorspaces */
    cinfo->write_Adobe_marker = FALSE; /* write no Adobe marker by default */
  
    switch (colorspace) {
    case JCS_GRAYSCALE:
      cinfo->write_JFIF_header = TRUE; /* Write a JFIF marker */
      cinfo->num_components = 1;
      /* JFIF specifies component ID 1 */
      SET_COMP(0, 1, 1,1, 0, 0,0);
      break;
    case JCS_RGB:
      cinfo->write_Adobe_marker = TRUE; /* write Adobe marker to flag RGB */
      cinfo->num_components = 3;
      SET_COMP(0, 0x52 /* 'R' */, 1,1, 0, 0,0);
      SET_COMP(1, 0x47 /* 'G' */, 1,1, 0, 0,0);
      SET_COMP(2, 0x42 /* 'B' */, 1,1, 0, 0,0);
      break;
    case JCS_YCbCr:
      cinfo->write_JFIF_header = TRUE; /* Write a JFIF marker */
      cinfo->num_components = 3;
      /* JFIF specifies component IDs 1,2,3 */
      /* We default to 2x2 subsamples of chrominance */
      SET_COMP(0, 1, 2,2, 0, 0,0);
      SET_COMP(1, 2, 1,1, 1, 1,1);
      SET_COMP(2, 3, 1,1, 1, 1,1);
      break;
    case JCS_CMYK:
      cinfo->write_Adobe_marker = TRUE; /* write Adobe marker to flag CMYK */
      cinfo->num_components = 4;
      SET_COMP(0, 0x43 /* 'C' */, 1,1, 0, 0,0);
      SET_COMP(1, 0x4D /* 'M' */, 1,1, 0, 0,0);
      SET_COMP(2, 0x59 /* 'Y' */, 1,1, 0, 0,0);
      SET_COMP(3, 0x4B /* 'K' */, 1,1, 0, 0,0);
      break;
    case JCS_YCCK:
      cinfo->write_Adobe_marker = TRUE; /* write Adobe marker to flag YCCK */
      cinfo->num_components = 4;
      SET_COMP(0, 1, 2,2, 0, 0,0);
      SET_COMP(1, 2, 1,1, 1, 1,1);
      SET_COMP(2, 3, 1,1, 1, 1,1);
      SET_COMP(3, 4, 2,2, 0, 0,0);
      break;
    case JCS_UNKNOWN:
      cinfo->num_components = cinfo->input_components;
      if (cinfo->num_components < 1 || cinfo->num_components > MAX_COMPONENTS)
        ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
  	       MAX_COMPONENTS);
      for (ci = 0; ci < cinfo->num_components; ci++) {
        SET_COMP(ci, ci, 1,1, 0, 0,0);
      }
      break;
    default:
      ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
    }
  }
  
  
  #ifdef C_PROGRESSIVE_SUPPORTED
  
  LOCAL(jpeg_scan_info *)
  fill_a_scan (jpeg_scan_info * scanptr, int ci,
  	     int Ss, int Se, int Ah, int Al)
  /* Support routine: generate one scan for specified component */
  {
    scanptr->comps_in_scan = 1;
    scanptr->component_index[0] = ci;
    scanptr->Ss = Ss;
    scanptr->Se = Se;
    scanptr->Ah = Ah;
    scanptr->Al = Al;
    scanptr++;
    return scanptr;
  }
  
  LOCAL(jpeg_scan_info *)
  fill_scans (jpeg_scan_info * scanptr, int ncomps,
  	    int Ss, int Se, int Ah, int Al)
  /* Support routine: generate one scan for each component */
  {
    int ci;
  
    for (ci = 0; ci < ncomps; ci++) {
      scanptr->comps_in_scan = 1;
      scanptr->component_index[0] = ci;
      scanptr->Ss = Ss;
      scanptr->Se = Se;
      scanptr->Ah = Ah;
      scanptr->Al = Al;
      scanptr++;
    }
    return scanptr;
  }
  
  LOCAL(jpeg_scan_info *)
  fill_dc_scans (jpeg_scan_info * scanptr, int ncomps, int Ah, int Al)
  /* Support routine: generate interleaved DC scan if possible, else N scans */
  {
    int ci;
  
    if (ncomps <= MAX_COMPS_IN_SCAN) {
      /* Single interleaved DC scan */
      scanptr->comps_in_scan = ncomps;
      for (ci = 0; ci < ncomps; ci++)
        scanptr->component_index[ci] = ci;
      scanptr->Ss = scanptr->Se = 0;
      scanptr->Ah = Ah;
      scanptr->Al = Al;
      scanptr++;
    } else {
      /* Noninterleaved DC scan for each component */
      scanptr = fill_scans(scanptr, ncomps, 0, 0, Ah, Al);
    }
    return scanptr;
  }
  
  
  /*
   * Create a recommended progressive-JPEG script.
   * cinfo->num_components and cinfo->jpeg_color_space must be correct.
   */
  
  GLOBAL(void)
  jpeg_simple_progression (j_compress_ptr cinfo)
  {
    int ncomps = cinfo->num_components;
    int nscans;
    jpeg_scan_info * scanptr;
  
    /* Safety check to ensure start_compress not called yet. */
    if (cinfo->global_state != CSTATE_START)
      ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
  
    /* Figure space needed for script.  Calculation must match code below! */
    if (ncomps == 3 && cinfo->jpeg_color_space == JCS_YCbCr) {
      /* Custom script for YCbCr color images. */
      nscans = 10;
    } else {
      /* All-purpose script for other color spaces. */
      if (ncomps > MAX_COMPS_IN_SCAN)
        nscans = 6 * ncomps;	/* 2 DC + 4 AC scans per component */
      else
        nscans = 2 + 4 * ncomps;	/* 2 DC scans; 4 AC scans per component */
    }
  
    /* Allocate space for script.
     * We need to put it in the permanent pool in case the application performs
     * multiple compressions without changing the settings.  To avoid a memory
     * leak if jpeg_simple_progression is called repeatedly for the same JPEG
     * object, we try to re-use previously allocated space, and we allocate
     * enough space to handle YCbCr even if initially asked for grayscale.
     */
    if (cinfo->script_space == NULL || cinfo->script_space_size < nscans) {
      cinfo->script_space_size = MAX(nscans, 10);
      cinfo->script_space = (jpeg_scan_info *)
        (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
  			cinfo->script_space_size * SIZEOF(jpeg_scan_info));
    }
    scanptr = cinfo->script_space;
    cinfo->scan_info = scanptr;
    cinfo->num_scans = nscans;
  
    if (ncomps == 3 && cinfo->jpeg_color_space == JCS_YCbCr) {
      /* Custom script for YCbCr color images. */
      /* Initial DC scan */
      scanptr = fill_dc_scans(scanptr, ncomps, 0, 1);
      /* Initial AC scan: get some luma data out in a hurry */
      scanptr = fill_a_scan(scanptr, 0, 1, 5, 0, 2);
      /* Chroma data is too small to be worth expending many scans on */
      scanptr = fill_a_scan(scanptr, 2, 1, 63, 0, 1);
      scanptr = fill_a_scan(scanptr, 1, 1, 63, 0, 1);
      /* Complete spectral selection for luma AC */
      scanptr = fill_a_scan(scanptr, 0, 6, 63, 0, 2);
      /* Refine next bit of luma AC */
      scanptr = fill_a_scan(scanptr, 0, 1, 63, 2, 1);
      /* Finish DC successive approximation */
      scanptr = fill_dc_scans(scanptr, ncomps, 1, 0);
      /* Finish AC successive approximation */
      scanptr = fill_a_scan(scanptr, 2, 1, 63, 1, 0);
      scanptr = fill_a_scan(scanptr, 1, 1, 63, 1, 0);
      /* Luma bottom bit comes last since it's usually largest scan */
      scanptr = fill_a_scan(scanptr, 0, 1, 63, 1, 0);
    } else {
      /* All-purpose script for other color spaces. */
      /* Successive approximation first pass */
      scanptr = fill_dc_scans(scanptr, ncomps, 0, 1);
      scanptr = fill_scans(scanptr, ncomps, 1, 5, 0, 2);
      scanptr = fill_scans(scanptr, ncomps, 6, 63, 0, 2);
      /* Successive approximation second pass */
      scanptr = fill_scans(scanptr, ncomps, 1, 63, 2, 1);
      /* Successive approximation final pass */
      scanptr = fill_dc_scans(scanptr, ncomps, 1, 0);
      scanptr = fill_scans(scanptr, ncomps, 1, 63, 1, 0);
    }
  }
  
  #endif /* C_PROGRESSIVE_SUPPORTED */
  