* This file was part of the Independent JPEG Group's software:
* Copyright (C) 1991-1998, Thomas G. Lane.
* Modified 2002-2009 by Guido Vollbeding.
* libjpeg-turbo Modifications:
* Copyright (C) 2009-2011, 2013-2014, 2016, D. R. Commander.
* Copyright (C) 2015, Google, Inc.
* For conditions of distribution and use, see the accompanying README.ijg
* This file defines the application interface for the JPEG library.
* Most applications using the library need only include this file,
* and perhaps jerror.h if they want to know the exact error codes.
* First we include the configuration files that record how this
* installation of the JPEG library is set up. jconfig.h can be
* generated automatically for many systems. jmorecfg.h contains
* manual configuration options that most people need not worry about.
#ifndef JCONFIG_INCLUDED /* in case jinclude.h already did */
#include "jconfig.h" /* widely used configuration options */
#include "jmorecfg.h" /* seldom changed options */
#ifndef DONT_USE_EXTERN_C
/* Various constants determining the sizes of things.
* All of these are specified by the JPEG standard, so don't change them
* if you want to be compatible.
#define DCTSIZE 8 /* The basic DCT block is 8x8 samples */
#define DCTSIZE2 64 /* DCTSIZE squared; # of elements in a block */
#define NUM_QUANT_TBLS 4 /* Quantization tables are numbered 0..3 */
#define NUM_HUFF_TBLS 4 /* Huffman tables are numbered 0..3 */
#define NUM_ARITH_TBLS 16 /* Arith-coding tables are numbered 0..15 */
#define MAX_COMPS_IN_SCAN 4 /* JPEG limit on # of components in one scan */
#define MAX_SAMP_FACTOR 4 /* JPEG limit on sampling factors */
/* Unfortunately, some bozo at Adobe saw no reason to be bound by the standard;
* the PostScript DCT filter can emit files with many more than 10 blocks/MCU.
* If you happen to run across such a file, you can up D_MAX_BLOCKS_IN_MCU
* to handle it. We even let you do this from the jconfig.h file. However,
* we strongly discourage changing C_MAX_BLOCKS_IN_MCU; just because Adobe
* sometimes emits noncompliant files doesn't mean you should too.
#define C_MAX_BLOCKS_IN_MCU 10 /* compressor's limit on blocks per MCU */
#ifndef D_MAX_BLOCKS_IN_MCU
#define D_MAX_BLOCKS_IN_MCU 10 /* decompressor's limit on blocks per MCU */
/* Data structures for images (arrays of samples and of DCT coefficients).
typedef JSAMPLE *JSAMPROW; /* ptr to one image row of pixel samples. */
typedef JSAMPROW *JSAMPARRAY; /* ptr to some rows (a 2-D sample array) */
typedef JSAMPARRAY *JSAMPIMAGE; /* a 3-D sample array: top index is color */
typedef JCOEF JBLOCK[DCTSIZE2]; /* one block of coefficients */
typedef JBLOCK *JBLOCKROW; /* pointer to one row of coefficient blocks */
typedef JBLOCKROW *JBLOCKARRAY; /* a 2-D array of coefficient blocks */
typedef JBLOCKARRAY *JBLOCKIMAGE; /* a 3-D array of coefficient blocks */
typedef JCOEF *JCOEFPTR; /* useful in a couple of places */
/* Types for JPEG compression parameters and working tables. */
/* DCT coefficient quantization tables. */
/* This array gives the coefficient quantizers in natural array order
* (not the zigzag order in which they are stored in a JPEG DQT marker).
* CAUTION: IJG versions prior to v6a kept this array in zigzag order.
UINT16 quantval[DCTSIZE2]; /* quantization step for each coefficient */
/* This field is used only during compression. It's initialized FALSE when
* the table is created, and set TRUE when it's been output to the file.
* You could suppress output of a table by setting this to TRUE.
* (See jpeg_suppress_tables for an example.)
boolean sent_table; /* TRUE when table has been output */
/* Huffman coding tables. */
/* These two fields directly represent the contents of a JPEG DHT marker */
UINT8 bits[17]; /* bits[k] = # of symbols with codes of */
/* length k bits; bits[0] is unused */
UINT8 huffval[256]; /* The symbols, in order of incr code length */
/* This field is used only during compression. It's initialized FALSE when
* the table is created, and set TRUE when it's been output to the file.
* You could suppress output of a table by setting this to TRUE.
* (See jpeg_suppress_tables for an example.)
boolean sent_table; /* TRUE when table has been output */
/* Basic info about one component (color channel). */
/* These values are fixed over the whole image. */
/* For compression, they must be supplied by parameter setup; */
/* for decompression, they are read from the SOF marker. */
int component_id; /* identifier for this component (0..255) */
int component_index; /* its index in SOF or cinfo->comp_info[] */
int h_samp_factor; /* horizontal sampling factor (1..4) */
int v_samp_factor; /* vertical sampling factor (1..4) */
int quant_tbl_no; /* quantization table selector (0..3) */
/* These values may vary between scans. */
/* For compression, they must be supplied by parameter setup; */
/* for decompression, they are read from the SOS marker. */
/* The decompressor output side may not use these variables. */
int dc_tbl_no; /* DC entropy table selector (0..3) */
int ac_tbl_no; /* AC entropy table selector (0..3) */
/* Remaining fields should be treated as private by applications. */
/* These values are computed during compression or decompression startup: */
/* Component's size in DCT blocks.
* Any dummy blocks added to complete an MCU are not counted; therefore
* these values do not depend on whether a scan is interleaved or not.
JDIMENSION width_in_blocks;
JDIMENSION height_in_blocks;
/* Size of a DCT block in samples. Always DCTSIZE for compression.
* For decompression this is the size of the output from one DCT block,
* reflecting any scaling we choose to apply during the IDCT step.
* Values from 1 to 16 are supported.
* Note that different components may receive different IDCT scalings.
#if JPEG_LIB_VERSION >= 70
/* The downsampled dimensions are the component's actual, unpadded number
* of samples at the main buffer (preprocessing/compression interface), thus
* downsampled_width = ceil(image_width * Hi/Hmax)
* and similarly for height. For decompression, IDCT scaling is included, so
* downsampled_width = ceil(image_width * Hi/Hmax * DCT_[h_]scaled_size/DCTSIZE)
JDIMENSION downsampled_width; /* actual width in samples */
JDIMENSION downsampled_height; /* actual height in samples */
/* This flag is used only for decompression. In cases where some of the
* components will be ignored (eg grayscale output from YCbCr image),
* we can skip most computations for the unused components.
boolean component_needed; /* do we need the value of this component? */
/* These values are computed before starting a scan of the component. */
/* The decompressor output side may not use these variables. */
int MCU_width; /* number of blocks per MCU, horizontally */
int MCU_height; /* number of blocks per MCU, vertically */
int MCU_blocks; /* MCU_width * MCU_height */
int MCU_sample_width; /* MCU width in samples, MCU_width*DCT_[h_]scaled_size */
int last_col_width; /* # of non-dummy blocks across in last MCU */
int last_row_height; /* # of non-dummy blocks down in last MCU */
/* Saved quantization table for component; NULL if none yet saved.
* See jdinput.c comments about the need for this information.
* This field is currently used only for decompression.
/* Private per-component storage for DCT or IDCT subsystem. */
/* The script for encoding a multiple-scan file is an array of these: */
int comps_in_scan; /* number of components encoded in this scan */
int component_index[MAX_COMPS_IN_SCAN]; /* their SOF/comp_info[] indexes */
int Ss, Se; /* progressive JPEG spectral selection parms */
int Ah, Al; /* progressive JPEG successive approx. parms */
/* The decompressor can save APPn and COM markers in a list of these: */
typedef struct jpeg_marker_struct *jpeg_saved_marker_ptr;
struct jpeg_marker_struct {
jpeg_saved_marker_ptr next; /* next in list, or NULL */
UINT8 marker; /* marker code: JPEG_COM, or JPEG_APP0+n */
unsigned int original_length; /* # bytes of data in the file */
unsigned int data_length; /* # bytes of data saved at data[] */
JOCTET *data; /* the data contained in the marker */
/* the marker length word is not counted in data_length or original_length */
/* Known color spaces. */
#define JCS_ALPHA_EXTENSIONS 1
JCS_UNKNOWN, /* error/unspecified */
JCS_GRAYSCALE, /* monochrome */
JCS_RGB, /* red/green/blue as specified by the RGB_RED,
RGB_GREEN, RGB_BLUE, and RGB_PIXELSIZE macros */
JCS_YCbCr, /* Y/Cb/Cr (also known as YUV) */
JCS_YCCK, /* Y/Cb/Cr/K */
JCS_EXT_RGB, /* red/green/blue */
JCS_EXT_RGBX, /* red/green/blue/x */
JCS_EXT_BGR, /* blue/green/red */
JCS_EXT_BGRX, /* blue/green/red/x */
JCS_EXT_XBGR, /* x/blue/green/red */
JCS_EXT_XRGB, /* x/red/green/blue */
/* When out_color_space it set to JCS_EXT_RGBX, JCS_EXT_BGRX, JCS_EXT_XBGR,
or JCS_EXT_XRGB during decompression, the X byte is undefined, and in
order to ensure the best performance, libjpeg-turbo can set that byte to
whatever value it wishes. Use the following colorspace constants to
ensure that the X byte is set to 0xFF, so that it can be interpreted as an
JCS_EXT_RGBA, /* red/green/blue/alpha */
JCS_EXT_BGRA, /* blue/green/red/alpha */
JCS_EXT_ABGR, /* alpha/blue/green/red */
JCS_EXT_ARGB, /* alpha/red/green/blue */
JCS_RGB565 /* 5-bit red/6-bit green/5-bit blue */
/* DCT/IDCT algorithm options. */
JDCT_ISLOW, /* slow but accurate integer algorithm */
JDCT_IFAST, /* faster, less accurate integer method */
JDCT_FLOAT /* floating-point: accurate, fast on fast HW */
#ifndef JDCT_DEFAULT /* may be overridden in jconfig.h */
#define JDCT_DEFAULT JDCT_ISLOW
#ifndef JDCT_FASTEST /* may be overridden in jconfig.h */
#define JDCT_FASTEST JDCT_IFAST
/* Dithering options for decompression. */
JDITHER_NONE, /* no dithering */
JDITHER_ORDERED, /* simple ordered dither */
JDITHER_FS /* Floyd-Steinberg error diffusion dither */
/* Common fields between JPEG compression and decompression master structs. */
#define jpeg_common_fields \
struct jpeg_error_mgr *err; /* Error handler module */\
struct jpeg_memory_mgr *mem; /* Memory manager module */\
struct jpeg_progress_mgr *progress; /* Progress monitor, or NULL if none */\
void *client_data; /* Available for use by application */\
boolean is_decompressor; /* So common code can tell which is which */\
int global_state /* For checking call sequence validity */
/* Routines that are to be used by both halves of the library are declared
* to receive a pointer to this structure. There are no actual instances of
* jpeg_common_struct, only of jpeg_compress_struct and jpeg_decompress_struct.
struct jpeg_common_struct {
jpeg_common_fields; /* Fields common to both master struct types */
/* Additional fields follow in an actual jpeg_compress_struct or
* jpeg_decompress_struct. All three structs must agree on these
* initial fields! (This would be a lot cleaner in C++.)
typedef struct jpeg_common_struct *j_common_ptr;
typedef struct jpeg_compress_struct *j_compress_ptr;
typedef struct jpeg_decompress_struct *j_decompress_ptr;
/* Master record for a compression instance */
struct jpeg_compress_struct {
jpeg_common_fields; /* Fields shared with jpeg_decompress_struct */
/* Destination for compressed data */
struct jpeg_destination_mgr *dest;
/* Description of source image --- these fields must be filled in by
* outer application before starting compression. in_color_space must
* be correct before you can even call jpeg_set_defaults().
JDIMENSION image_width; /* input image width */
JDIMENSION image_height; /* input image height */
int input_components; /* # of color components in input image */
J_COLOR_SPACE in_color_space; /* colorspace of input image */
double input_gamma; /* image gamma of input image */
/* Compression parameters --- these fields must be set before calling
* jpeg_start_compress(). We recommend calling jpeg_set_defaults() to
* initialize everything to reasonable defaults, then changing anything
* the application specifically wants to change. That way you won't get
* burnt when new parameters are added. Also note that there are several
* helper routines to simplify changing parameters.
#if JPEG_LIB_VERSION >= 70
unsigned int scale_num, scale_denom; /* fraction by which to scale image */
JDIMENSION jpeg_width; /* scaled JPEG image width */
JDIMENSION jpeg_height; /* scaled JPEG image height */
/* Dimensions of actual JPEG image that will be written to file,
* derived from input dimensions by scaling factors above.
* These fields are computed by jpeg_start_compress().
* You can also use jpeg_calc_jpeg_dimensions() to determine these values
* in advance of calling jpeg_start_compress().
int data_precision; /* bits of precision in image data */
int num_components; /* # of color components in JPEG image */
J_COLOR_SPACE jpeg_color_space; /* colorspace of JPEG image */
jpeg_component_info *comp_info;
/* comp_info[i] describes component that appears i'th in SOF */
JQUANT_TBL *quant_tbl_ptrs[NUM_QUANT_TBLS];
#if JPEG_LIB_VERSION >= 70
int q_scale_factor[NUM_QUANT_TBLS];
/* ptrs to coefficient quantization tables, or NULL if not defined,
* and corresponding scale factors (percentage, initialized 100).
JHUFF_TBL *dc_huff_tbl_ptrs[NUM_HUFF_TBLS];
JHUFF_TBL *ac_huff_tbl_ptrs[NUM_HUFF_TBLS];
/* ptrs to Huffman coding tables, or NULL if not defined */
UINT8 arith_dc_L[NUM_ARITH_TBLS]; /* L values for DC arith-coding tables */
UINT8 arith_dc_U[NUM_ARITH_TBLS]; /* U values for DC arith-coding tables */
UINT8 arith_ac_K[NUM_ARITH_TBLS]; /* Kx values for AC arith-coding tables */
int num_scans; /* # of entries in scan_info array */
const jpeg_scan_info *scan_info; /* script for multi-scan file, or NULL */
/* The default value of scan_info is NULL, which causes a single-scan
* sequential JPEG file to be emitted. To create a multi-scan file,
* set num_scans and scan_info to point to an array of scan definitions.
boolean raw_data_in; /* TRUE=caller supplies downsampled data */
boolean arith_code; /* TRUE=arithmetic coding, FALSE=Huffman */
boolean optimize_coding; /* TRUE=optimize entropy encoding parms */
boolean CCIR601_sampling; /* TRUE=first samples are cosited */
#if JPEG_LIB_VERSION >= 70
boolean do_fancy_downsampling; /* TRUE=apply fancy downsampling */
int smoothing_factor; /* 1..100, or 0 for no input smoothing */
J_DCT_METHOD dct_method; /* DCT algorithm selector */
/* The restart interval can be specified in absolute MCUs by setting
* restart_interval, or in MCU rows by setting restart_in_rows
* (in which case the correct restart_interval will be figured
unsigned int restart_interval; /* MCUs per restart, or 0 for no restart */
int restart_in_rows; /* if > 0, MCU rows per restart interval */
/* Parameters controlling emission of special markers. */
boolean write_JFIF_header; /* should a JFIF marker be written? */
UINT8 JFIF_major_version; /* What to write for the JFIF version number */
UINT8 JFIF_minor_version;
/* These three values are not used by the JPEG code, merely copied */
/* into the JFIF APP0 marker. density_unit can be 0 for unknown, */
/* 1 for dots/inch, or 2 for dots/cm. Note that the pixel aspect */
/* ratio is defined by X_density/Y_density even when density_unit=0. */
UINT8 density_unit; /* JFIF code for pixel size units */
UINT16 X_density; /* Horizontal pixel density */
UINT16 Y_density; /* Vertical pixel density */
boolean write_Adobe_marker; /* should an Adobe marker be written? */
/* State variable: index of next scanline to be written to
* jpeg_write_scanlines(). Application may use this to control its
* processing loop, e.g., "while (next_scanline < image_height)".
JDIMENSION next_scanline; /* 0 .. image_height-1 */
/* Remaining fields are known throughout compressor, but generally
* should not be touched by a surrounding application.
* These fields are computed during compression startup
boolean progressive_mode; /* TRUE if scan script uses progressive mode */
int max_h_samp_factor; /* largest h_samp_factor */
int max_v_samp_factor; /* largest v_samp_factor */
#if JPEG_LIB_VERSION >= 70
int min_DCT_h_scaled_size; /* smallest DCT_h_scaled_size of any component */
int min_DCT_v_scaled_size; /* smallest DCT_v_scaled_size of any component */
JDIMENSION total_iMCU_rows; /* # of iMCU rows to be input to coef ctlr */
/* The coefficient controller receives data in units of MCU rows as defined
* for fully interleaved scans (whether the JPEG file is interleaved or not).
* There are v_samp_factor * DCTSIZE sample rows of each component in an
* "iMCU" (interleaved MCU) row.
* These fields are valid during any one scan.
* They describe the components and MCUs actually appearing in the scan.
int comps_in_scan; /* # of JPEG components in this scan */
jpeg_component_info *cur_comp_info[MAX_COMPS_IN_SCAN];
/* *cur_comp_info[i] describes component that appears i'th in SOS */
JDIMENSION MCUs_per_row; /* # of MCUs across the image */
JDIMENSION MCU_rows_in_scan; /* # of MCU rows in the image */
int blocks_in_MCU; /* # of DCT blocks per MCU */
int MCU_membership[C_MAX_BLOCKS_IN_MCU];
/* MCU_membership[i] is index in cur_comp_info of component owning */
/* i'th block in an MCU */
int Ss, Se, Ah, Al; /* progressive JPEG parameters for scan */
#if JPEG_LIB_VERSION >= 80
int block_size; /* the basic DCT block size: 1..16 */
const int *natural_order; /* natural-order position array */
int lim_Se; /* min( Se, DCTSIZE2-1 ) */
* Links to compression subobjects (methods and private variables of modules)
struct jpeg_comp_master *master;
struct jpeg_c_main_controller *main;
struct jpeg_c_prep_controller *prep;
struct jpeg_c_coef_controller *coef;
struct jpeg_marker_writer *marker;
struct jpeg_color_converter *cconvert;
struct jpeg_downsampler *downsample;
struct jpeg_forward_dct *fdct;
struct jpeg_entropy_encoder *entropy;
jpeg_scan_info *script_space; /* workspace for jpeg_simple_progression */
/* Master record for a decompression instance */
struct jpeg_decompress_struct {
jpeg_common_fields; /* Fields shared with jpeg_compress_struct */
/* Source of compressed data */
struct jpeg_source_mgr *src;
/* Basic description of image --- filled in by jpeg_read_header(). */
/* Application may inspect these values to decide how to process image. */
JDIMENSION image_width; /* nominal image width (from SOF marker) */
JDIMENSION image_height; /* nominal image height */
int num_components; /* # of color components in JPEG image */
J_COLOR_SPACE jpeg_color_space; /* colorspace of JPEG image */
/* Decompression processing parameters --- these fields must be set before
* calling jpeg_start_decompress(). Note that jpeg_read_header() initializes
* them to default values.
J_COLOR_SPACE out_color_space; /* colorspace for output */
unsigned int scale_num, scale_denom; /* fraction by which to scale image */
double output_gamma; /* image gamma wanted in output */
boolean buffered_image; /* TRUE=multiple output passes */
boolean raw_data_out; /* TRUE=downsampled data wanted */
J_DCT_METHOD dct_method; /* IDCT algorithm selector */
It is recommended that you Edit text format, this type of Fix handles quite a lot in one request
