jcparam.c File Reference

#include "jinclude.h"
#include "jpeglib.h"

Include dependency graph for jcparam.c:

Go to the source code of this file.

Macros
#define	JPEG_INTERNALS
#define	SET_COMP(index, id, hsamp, vsamp, quant, dctbl, actbl)

Functions
	jpeg_add_quant_table (j_compress_ptr cinfo, int which_tbl, const unsigned int *basic_table, int scale_factor, boolean force_baseline)
	jpeg_default_qtables (j_compress_ptr cinfo, boolean force_baseline)
	jpeg_set_linear_quality (j_compress_ptr cinfo, int scale_factor, boolean force_baseline)
	jpeg_quality_scaling (int quality)
	jpeg_set_quality (j_compress_ptr cinfo, int quality, boolean force_baseline)
	std_huff_tables (j_compress_ptr cinfo)
	jpeg_set_defaults (j_compress_ptr cinfo)
	jpeg_default_colorspace (j_compress_ptr cinfo)
	jpeg_set_colorspace (j_compress_ptr cinfo, J_COLOR_SPACE colorspace)

Variables
static const unsigned int	std_luminance_quant_tbl [DCTSIZE2]
static const unsigned int	std_chrominance_quant_tbl [DCTSIZE2]

Macro Definition Documentation

JPEG_INTERNALS

#define JPEG_INTERNALS

Definition at line 14 of file jcparam.c.

SET_COMP

#define SET_COMP	(		index,
			id,
			hsamp,
			vsamp,
			quant,
			dctbl,
			actbl
	)

Value:

  (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) )

Function Documentation

jpeg_add_quant_table()

jpeg_add_quant_table	(	j_compress_ptr	cinfo,
		int	which_tbl,
		const unsigned int *	basic_table,
		int	scale_factor,
		boolean	force_baseline
	)

Definition at line 24 of file jcparam.c.

{
  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;
}

Referenced by jpeg_default_qtables(), jpeg_set_linear_quality(), and read_quant_tables().

jpeg_default_colorspace()

jpeg_default_colorspace

(

j_compress_ptr

cinfo

)

Definition at line 297 of file jcparam.c.

{
  switch (cinfo->in_color_space) {
  case JCS_UNKNOWN:
    jpeg_set_colorspace(cinfo, JCS_UNKNOWN);
    break;
  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_BG_RGB:
    /* No translation for now -- conversion to BG_YCC not yet supportet */
    jpeg_set_colorspace(cinfo, JCS_BG_RGB);
    break;
  case JCS_BG_YCC:
    jpeg_set_colorspace(cinfo, JCS_BG_YCC);
    break;
  default:
    ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
  }
}

Referenced by jpeg_set_defaults(), and main().

jpeg_default_qtables()

jpeg_default_qtables	(	j_compress_ptr	cinfo,
		boolean	force_baseline
	)

Definition at line 91 of file jcparam.c.

{
  /* Set up two quantization tables using the specified scaling */
  jpeg_add_quant_table(cinfo, 0, std_luminance_quant_tbl,
               cinfo->q_scale_factor[0], force_baseline);
  jpeg_add_quant_table(cinfo, 1, std_chrominance_quant_tbl,
               cinfo->q_scale_factor[1], force_baseline);
}

Referenced by set_quality_ratings().

jpeg_quality_scaling()

jpeg_quality_scaling

(

int

quality

)

Definition at line 123 of file jcparam.c.

{
  /* 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;
}

Referenced by jpeg_set_quality(), and set_quality_ratings().

jpeg_set_colorspace()

jpeg_set_colorspace	(	j_compress_ptr	cinfo,
		J_COLOR_SPACE	colorspace
	)

Definition at line 336 of file jcparam.c.

{
  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_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;
  case JCS_GRAYSCALE:
    cinfo->write_JFIF_header = TRUE; /* Write a JFIF marker */
    cinfo->num_components = 1;
    /* JFIF specifies component ID 1 */
    SET_COMP(0, 0x01, 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,
        cinfo->color_transform == JCT_SUBTRACT_GREEN ? 1 : 0,
        cinfo->color_transform == JCT_SUBTRACT_GREEN ? 1 : 0);
    SET_COMP(1, 0x47 /* 'G' */, 1,1, 0, 0,0);
    SET_COMP(2, 0x42 /* 'B' */, 1,1, 0,
        cinfo->color_transform == JCT_SUBTRACT_GREEN ? 1 : 0,
        cinfo->color_transform == JCT_SUBTRACT_GREEN ? 1 : 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, 0x01, 2,2, 0, 0,0);
    SET_COMP(1, 0x02, 1,1, 1, 1,1);
    SET_COMP(2, 0x03, 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, 0x01, 2,2, 0, 0,0);
    SET_COMP(1, 0x02, 1,1, 1, 1,1);
    SET_COMP(2, 0x03, 1,1, 1, 1,1);
    SET_COMP(3, 0x04, 2,2, 0, 0,0);
    break;
  case JCS_BG_RGB:
    cinfo->write_JFIF_header = TRUE; /* Write a JFIF marker */
    cinfo->JFIF_major_version = 2;   /* Set JFIF major version = 2 */
    cinfo->num_components = 3;
    /* Add offset 0x20 to the normal R/G/B component IDs */
    SET_COMP(0, 0x72 /* 'r' */, 1,1, 0,
        cinfo->color_transform == JCT_SUBTRACT_GREEN ? 1 : 0,
        cinfo->color_transform == JCT_SUBTRACT_GREEN ? 1 : 0);
    SET_COMP(1, 0x67 /* 'g' */, 1,1, 0, 0,0);
    SET_COMP(2, 0x62 /* 'b' */, 1,1, 0,
        cinfo->color_transform == JCT_SUBTRACT_GREEN ? 1 : 0,
        cinfo->color_transform == JCT_SUBTRACT_GREEN ? 1 : 0);
    break;
  case JCS_BG_YCC:
    cinfo->write_JFIF_header = TRUE; /* Write a JFIF marker */
    cinfo->JFIF_major_version = 2;   /* Set JFIF major version = 2 */
    cinfo->num_components = 3;
    /* Add offset 0x20 to the normal Cb/Cr component IDs */
    /* We default to 2x2 subsamples of chrominance */
    SET_COMP(0, 0x01, 2,2, 0, 0,0);
    SET_COMP(1, 0x22, 1,1, 1, 1,1);
    SET_COMP(2, 0x23, 1,1, 1, 1,1);
    break;
  default:
    ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
  }
}

Referenced by jpeg_copy_critical_parameters(), jpeg_default_colorspace(), and parse_switches().

jpeg_set_defaults()

jpeg_set_defaults

(

j_compress_ptr

cinfo

)

Definition at line 196 of file jcparam.c.

{
  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->scale_num = 1;     /* 1:1 scaling */
  cinfo->scale_denom = 1;
  cinfo->data_precision = BITS_IN_JSAMPLE;
  /* Set up two quantization tables using default quality of 75 */
  jpeg_set_quality(cinfo, 75, TRUE);
  /* Reset standard 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;
 
  /* The standard Huffman tables are only valid for 8-bit data precision.
   * If the precision is higher, use arithmetic coding.
   * (Alternatively, using Huffman coding would be possible with forcing
   * optimization on so that usable tables will be computed, or by
   * supplying default tables that are valid for the desired precision.)
   * Otherwise, use Huffman coding by default.
   */
  cinfo->arith_code = cinfo->data_precision > 8 ? TRUE : FALSE;
 
  /* 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;
 
  /* By default, apply fancy downsampling */
  cinfo->do_fancy_downsampling = TRUE;
 
  /* 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.
   *
   * For wide gamut colorspaces (BG_RGB and BG_YCC), the major version will be
   * overridden by jpeg_set_colorspace and set to 2.
   */
  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;
 
  /* No color transform */
  cinfo->color_transform = JCT_NONE;
 
  /* Choose JPEG colorspace based on input space, set defaults accordingly */
 
  jpeg_default_colorspace(cinfo);
}

Referenced by jpeg_copy_critical_parameters(), main(), and write_JPEG_file().

jpeg_set_linear_quality()

jpeg_set_linear_quality	(	j_compress_ptr	cinfo,
		int	scale_factor,
		boolean	force_baseline
	)

Definition at line 106 of file jcparam.c.

{
  /* 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);
}

Referenced by jpeg_set_quality().

jpeg_set_quality()

jpeg_set_quality	(	j_compress_ptr	cinfo,
		int	quality,
		boolean	force_baseline
	)

Definition at line 149 of file jcparam.c.

{
  /* 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);
}

Referenced by jpeg_set_defaults(), and write_JPEG_file().

std_huff_tables()

std_huff_tables

(

j_compress_ptr

cinfo

)

Definition at line 169 of file jcparam.c.

{
  if (cinfo->dc_huff_tbl_ptrs[0] != NULL)
    (void) jpeg_std_huff_table((j_common_ptr) cinfo, TRUE, 0);
 
  if (cinfo->ac_huff_tbl_ptrs[0] != NULL)
    (void) jpeg_std_huff_table((j_common_ptr) cinfo, FALSE, 0);
 
  if (cinfo->dc_huff_tbl_ptrs[1] != NULL)
    (void) jpeg_std_huff_table((j_common_ptr) cinfo, TRUE, 1);
 
  if (cinfo->ac_huff_tbl_ptrs[1] != NULL)
    (void) jpeg_std_huff_table((j_common_ptr) cinfo, FALSE, 1);
}

Referenced by jpeg_set_defaults().

Variable Documentation

std_chrominance_quant_tbl

const unsigned int std_chrominance_quant_tbl[DCTSIZE2]

static

Initial value:

= {
  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
}

Definition at line 78 of file jcparam.c.

Referenced by jpeg_default_qtables(), and jpeg_set_linear_quality().

std_luminance_quant_tbl

const unsigned int std_luminance_quant_tbl[DCTSIZE2]

static

Initial value:

= {
  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
}

Definition at line 68 of file jcparam.c.

Referenced by jpeg_default_qtables(), and jpeg_set_linear_quality().