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* jpeglib.h
* 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 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.
#ifndef JPEGLIB_H
#define JPEGLIB_H
* 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 */
/* Version ID for the JPEG library.
* Might be useful for tests like "#if JPEG_LIB_VERSION >= 60".
#define JPEG_LIB_VERSION 62 /* Version 6b */
/* 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 */
#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).
* On 80x86 machines, the image arrays are too big for near pointers,
* but the pointer arrays can fit in near memory.
typedef JSAMPLE FAR *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 FAR *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 FAR *JCOEFPTR; /* useful in a couple of places */
/* Types for JPEG compression parameters and working tables. */
/* DCT coefficient quantization tables. */
typedef struct {
/* 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. */
typedef struct {
/* 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). */
typedef struct {
/* 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 of 1,2,4,8 are likely to be supported. Note that different
* components may receive different IDCT scalings.
int DCT_scaled_size;
/* 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_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_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.
JQUANT_TBL * quant_table;
/* Private per-component storage for DCT or IDCT subsystem. */
void * dct_table;
} jpeg_component_info;
/* The script for encoding a multiple-scan file is an array of these: */
typedef struct {
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 */
} jpeg_scan_info;
/* The decompressor can save APPn and COM markers in a list of these: */
typedef struct jpeg_marker_struct FAR * 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 FAR * data; /* the data contained in the marker */
/* the marker length word is not counted in data_length or original_length */
/* Known color spaces. */
typedef enum {
JCS_UNKNOWN, /* error/unspecified */
JCS_GRAYSCALE, /* monochrome */
JCS_RGB, /* red/green/blue */
JCS_YCbCr, /* Y/Cb/Cr (also known as YUV) */
JCS_CMYK, /* C/M/Y/K */
JCS_YCCK, /* Y/Cb/Cr/K */
JCS_RGBA_8888, /* red/green/blue/alpha */
JCS_RGB_565 /* red/green/blue in 565 format */
/* DCT/IDCT algorithm options. */
typedef enum {
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 */
#ifndef JDCT_FASTEST /* may be overridden in jconfig.h */
/* Dithering options for decompression. */
typedef enum {
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.
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];
/* ptrs to coefficient quantization tables, or NULL if not defined */
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 */
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
* for each scan).
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 */
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 */
* 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 */
int script_space_size;
/* 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 original_image_width; /* nominal image width (from SOF marker) */
JDIMENSION image_width; /* nominal image width (from SOF marker)
may be changed by tile decode */
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 */
boolean do_fancy_upsampling; /* TRUE=apply fancy upsampling */
boolean do_block_smoothing; /* TRUE=apply interblock smoothing */
boolean quantize_colors; /* TRUE=colormapped output wanted */
/* the following are ignored if not quantize_colors: */
J_DITHER_MODE dither_mode; /* type of color dithering to use */
boolean two_pass_quantize; /* TRUE=use two-pass color quantization */
int desired_number_of_colors; /* max # colors to use in created colormap */
/* these are significant only in buffered-image mode: */
boolean enable_1pass_quant; /* enable future use of 1-pass quantizer */
boolean enable_external_quant;/* enable future use of external colormap */
boolean enable_2pass_quant; /* enable future use of 2-pass quantizer */
/* Description of actual output image that will be returned to application.
* These fields are computed by jpeg_start_decompress().
* You can also use jpeg_calc_output_dimensions() to determine these values
* in advance of calling jpeg_start_decompress().
JDIMENSION output_width; /* scaled image width */
JDIMENSION output_height; /* scaled image height */
int out_color_components; /* # of color components in out_color_space */
int output_components; /* # of color components returned */
/* output_components is 1 (a colormap index) when quantizing colors;
* otherwise it equals out_color_components.
int rec_outbuf_height; /* min recommended height of scanline buffer */
/* If the buffer passed to jpeg_read_scanlines() is less than this many rows
* high, space and time will be wasted due to unnecessary data copying.
* Usually rec_outbuf_height will be 1 or 2, at most 4.
/* When quantizing colors, the output colormap is described by these fields.
* The application can supply a colormap by setting colormap non-NULL before
* calling jpeg_start_decompress; otherwise a colormap is created during
* jpeg_start_decompress or jpeg_start_output.
* The map has out_color_components rows and actual_number_of_colors columns.
int actual_number_of_colors; /* number of entries in use */
JSAMPARRAY colormap; /* The color map as a 2-D pixel array */
/* State variables: these variables indicate the progress of decompression.
* The application may examine these but must not modify them.
/* Row index of next scanline to be read from jpeg_read_scanlines().
* Application may use this to control its processing loop, e.g.,
* "while (output_scanline < output_height)".
JDIMENSION output_scanline; /* 0 .. output_height-1 */
/* Current input scan number and number of iMCU rows completed in scan.
* These indicate the progress of the decompressor input side.
int input_scan_number; /* Number of SOS markers seen so far */
JDIMENSION input_iMCU_row; /* Number of iMCU rows completed */
/* The "output scan number" is the notional scan being displayed by the
* output side. The decompressor will not allow output scan/row number
* to get ahead of input scan/row, but it can fall arbitrarily far behind.
int output_scan_number; /* Nominal scan number being displayed */
JDIMENSION output_iMCU_row; /* Number of iMCU rows read */
/* Current progression status. coef_bits[c][i] indicates the precision
* with which component c's DCT coefficient i (in zigzag order) is known.
* It is -1 when no data has yet been received, otherwise it is the point
* transform (shift) value for the most recent scan of the coefficient
* (thus, 0 at completion of the progression).
* This pointer is NULL when reading a non-progressive file.
int (*coef_bits)[DCTSIZE2]; /* -1 or current Al value for each coef */
/* Internal JPEG parameters --- the application usually need not look at
* these fields. Note that the decompressor output side may not use
* any parameters that can change between scans.
/* Quantization and Huffman tables are carried forward across input
* datastreams when processing abbreviated JPEG datastreams.
JQUANT_TBL * quant_tbl_ptrs[NUM_QUANT_TBLS];
/* ptrs to coefficient quantization tables, or NULL if not defined */
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 */
/* These parameters are never carried across datastreams, since they
* are given in SOF/SOS markers or defined to be reset by SOI.
int data_precision; /* bits of precision in image data */
jpeg_component_info * comp_info;
/* comp_info[i] describes component that appears i'th in SOF */
boolean tile_decode; /* TRUE if using tile based decoding */
boolean progressive_mode; /* TRUE if SOFn specifies progressive mode */
boolean arith_code; /* TRUE=arithmetic coding, FALSE=Huffman */
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 */
unsigned int restart_interval; /* MCUs per restart interval, or 0 for no restart */
/* These fields record data obtained from optional markers recognized by
* the JPEG library.
boolean saw_JFIF_marker; /* TRUE iff a JFIF APP0 marker was found */
/* Data copied from JFIF marker; only valid if saw_JFIF_marker is TRUE: */
UINT8 JFIF_major_version; /* JFIF version number */
UINT8 JFIF_minor_version;
UINT8 density_unit; /* JFIF code for pixel size units */
UINT16 X_density; /* Horizontal pixel density */
UINT16 Y_density; /* Vertical pixel density */
boolean saw_Adobe_marker; /* TRUE iff an Adobe APP14 marker was found */
UINT8 Adobe_transform; /* Color transform code from Adobe marker */
boolean CCIR601_sampling; /* TRUE=first samples are cosited */
/* Aside from the specific data retained from APPn markers known to the
* library, the uninterpreted contents of any or all APPn and COM markers
* can be saved in a list for examination by the application.
jpeg_saved_marker_ptr marker_list; /* Head of list of saved markers */
/* Remaining fields are known throughout decompressor, but generally
* should not be touched by a surrounding application.
* These fields are computed during decompression startup
int max_h_samp_factor; /* largest h_samp_factor */
int max_v_samp_factor; /* largest v_samp_factor */
int min_DCT_scaled_size; /* smallest DCT_scaled_size of any component */
JDIMENSION total_iMCU_rows; /* # of iMCU rows in image */
/* The coefficient controller's input and output progress is measured in
* units of "iMCU" (interleaved MCU) rows. These are the same as MCU rows
* in fully interleaved JPEG scans, but are used whether the scan is
* interleaved or not. We define an iMCU row as v_samp_factor DCT block
* rows of each component. Therefore, the IDCT output contains
* v_samp_factor*DCT_scaled_size sample rows of a component per iMCU row.
JSAMPLE * sample_range_limit; /* table for fast range-limiting */
* These fields are valid during any one scan.
* They describe the components and MCUs actually appearing in the scan.
* Note that the decompressor output side must not use these fields.
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[D_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 */
/* This field is shared between entropy decoder and marker parser.
* It is either zero or the code of a JPEG marker that has been
* read from the data source, but has not yet been processed.
int unread_marker;
* Links to decompression subobjects (methods, private variables of modules)
struct jpeg_decomp_master * master;
struct jpeg_d_main_controller * main;
struct jpeg_d_coef_controller * coef;
struct jpeg_d_post_controller * post;
struct jpeg_input_controller * inputctl;
struct jpeg_marker_reader * marker;
struct jpeg_entropy_decoder * entropy;
struct jpeg_inverse_dct * idct;
struct jpeg_upsampler * upsample;
struct jpeg_color_deconverter * cconvert;
struct jpeg_color_quantizer * cquantize;
typedef struct {
// |--- byte_offset ---|- bit_left -|
// \------ 27 -------/ \---- 5 ----/
unsigned int bitstream_offset;
short prev_dc[3];
// remaining EOBs in EOBRUN
unsigned short EOBRUN;
// save the decoder current bit buffer, entropy->bitstate.get_buffer.
INT32 get_buffer;
// save the restart info.
unsigned short restarts_to_go;
unsigned char next_restart_num;
} huffman_offset_data;
typedef struct {
// The header starting position of this scan
unsigned int bitstream_offset;
// Number of components in this scan
int comps_in_scan;
// Number of MCUs in each row
int MCUs_per_row;
int MCU_rows_per_iMCU_row;
// The last MCU position and its dc value in this scan
huffman_offset_data prev_MCU_offset;
huffman_offset_data **offset;
} huffman_scan_header;
typedef struct {
// The number of MCUs that we sample each time as an index point
int MCU_sample_size;
// Number of scan in this image
int scan_count;
// Number of iMCUs rows in this image
int total_iMCU_rows;
// Memory used by scan struct
size_t mem_used;
huffman_scan_header *scan;
} huffman_index;
/* "Object" declarations for JPEG modules that may be supplied or called
* directly by the surrounding application.
* As with all objects in the JPEG library, these structs only define the
* publicly visible methods and state variables of a module. Additional
* private fields may exist after the public ones.
/* Error handler object */
struct jpeg_error_mgr {
/* Error exit handler: does not return to caller */
JMETHOD(void, error_exit, (j_common_ptr cinfo));
/* Conditionally emit a trace or warning message */
JMETHOD(void, emit_message, (j_common_ptr cinfo, int msg_level));
/* Routine that actually outputs a trace or error message */
JMETHOD(void, output_message, (j_common_ptr cinfo));
/* Format a message string for the most recent JPEG error or message */
JMETHOD(void, format_message, (j_common_ptr cinfo, char * buffer));
#define JMSG_LENGTH_MAX 200 /* recommended size of format_message buffer */
/* Reset error state variables at start of a new image */
JMETHOD(void, reset_error_mgr, (j_common_ptr cinfo));
/* The message ID code and any parameters are saved here.
* A message can have one string parameter or up to 8 int parameters.
int msg_code;
#define JMSG_STR_PARM_MAX 80
union {
int i[8];
} msg_parm;
/* Standard state variables for error facility */
int trace_level; /* max msg_level that will be displayed */
/* For recoverable corrupt-data errors, we emit a warning message,
* but keep going unless emit_message chooses to abort. emit_message
* should count warnings in num_warnings. The surrounding application
* can check for bad data by seeing if num_warnings is nonzero at the
* end of processing.
long num_warnings; /* number of corrupt-data warnings */
/* These fields point to the table(s) of error message strings.
* An application can change the table pointer to switch to a different
* message list (typically, to change the language in which errors are
* reported). Some applications may wish to add additional error codes
* that will be handled by the JPEG library error mechanism; the second
* table pointer is used for this purpose.
* First table includes all errors generated by JPEG library itself.
* Error code 0 is reserved for a "no such error string" message.
const char * const * jpeg_message_table; /* Library errors */
int last_jpeg_message; /* Table contains strings 0..last_jpeg_message */
/* Second table can be added by application (see cjpeg/djpeg for example).
* It contains strings numbered first_addon_message..last_addon_message.
const char * const * addon_message_table; /* Non-library errors */
int first_addon_message; /* code for first string in addon table */
int last_addon_message; /* code for last string in addon table */
/* Progress monitor object */
struct jpeg_progress_mgr {
JMETHOD(void, progress_monitor, (j_common_ptr cinfo));
long pass_counter; /* work units completed in this pass */
long pass_limit; /* total number of work units in this pass */
int completed_passes; /* passes completed so far */
int total_passes; /* total number of passes expected */
/* Data destination object for compression */
struct jpeg_destination_mgr {
JOCTET * next_output_byte; /* => next byte to write in buffer */
size_t free_in_buffer; /* # of byte spaces remaining in buffer */
JMETHOD(void, init_destination, (j_compress_ptr cinfo));
JMETHOD(boolean, empty_output_buffer, (j_compress_ptr cinfo));
JMETHOD(void, term_destination, (j_compress_ptr cinfo));
/* Data source object for decompression */
struct jpeg_source_mgr {
const JOCTET * next_input_byte; /* => next byte to read from buffer */
const JOCTET * start_input_byte; /* => first byte to read from input */
size_t bytes_in_buffer; /* # of bytes remaining in buffer */
size_t current_offset; /* current readed input offset */
JMETHOD(void, init_source, (j_decompress_ptr cinfo));
JMETHOD(boolean, fill_input_buffer, (j_decompress_ptr cinfo));
JMETHOD(void, skip_input_data, (j_decompress_ptr cinfo, long num_bytes));
JMETHOD(boolean, resync_to_restart, (j_decompress_ptr cinfo, int desired));
JMETHOD(void, term_source, (j_decompress_ptr cinfo));
JMETHOD(boolean, seek_input_data, (j_decompress_ptr cinfo, long byte_offset));
/* Memory manager object.
* Allocates "small" objects (a few K total), "large" objects (tens of K),
* and "really big" objects (virtual arrays with backing store if needed).
* The memory manager does not allow individual objects to be freed; rather,
* each created object is assigned to a pool, and whole pools can be freed
* at once. This is faster and more convenient than remembering exactly what
* to free, especially where malloc()/free() are not too speedy.
* NB: alloc routines never return NULL. They exit to error_exit if not
* successful.
#define JPOOL_PERMANENT 0 /* lasts until master record is destroyed */
#define JPOOL_IMAGE 1 /* lasts until done with image/datastream */
typedef struct jvirt_sarray_control * jvirt_sarray_ptr;
typedef struct jvirt_barray_control * jvirt_barray_ptr;
struct jpeg_memory_mgr {
/* Method pointers */
JMETHOD(void *, alloc_small, (j_common_ptr cinfo, int pool_id,
size_t sizeofobject));
JMETHOD(void FAR *, alloc_large, (j_common_ptr cinfo, int pool_id,
size_t sizeofobject));
JMETHOD(JSAMPARRAY, alloc_sarray, (j_common_ptr cinfo, int pool_id,
JDIMENSION samplesperrow,
JDIMENSION numrows));
JMETHOD(JBLOCKARRAY, alloc_barray, (j_common_ptr cinfo, int pool_id,
JDIMENSION blocksperrow,
JDIMENSION numrows));
JMETHOD(jvirt_sarray_ptr, request_virt_sarray, (j_common_ptr cinfo,
int pool_id,
boolean pre_zero,
JDIMENSION samplesperrow,
JDIMENSION maxaccess));
JMETHOD(jvirt_barray_ptr, request_virt_barray, (j_common_ptr cinfo,
int pool_id,
boolean pre_zero,
JDIMENSION blocksperrow,
JDIMENSION maxaccess));
JMETHOD(void, realize_virt_arrays, (j_common_ptr cinfo));
JMETHOD(JSAMPARRAY, access_virt_sarray, (j_common_ptr cinfo,
jvirt_sarray_ptr ptr,
JDIMENSION start_row,
JDIMENSION num_rows,
boolean writable));
JMETHOD(JBLOCKARRAY, access_virt_barray, (j_common_ptr cinfo,
jvirt_barray_ptr ptr,
JDIMENSION start_row,
JDIMENSION num_rows,
boolean writable));
JMETHOD(void, free_pool, (j_common_ptr cinfo, int pool_id));
JMETHOD(void, self_destruct, (j_common_ptr cinfo));
/* Limit on memory allocation for this JPEG object. (Note that this is
* merely advisory, not a guaranteed maximum; it only affects the space
* used for virtual-array buffers.) May be changed by outer application
* after creating the JPEG object.
long max_memory_to_use;
/* Maximum allocation request accepted by alloc_large. */
long max_alloc_chunk;
/* Routine signature for application-supplied marker processing methods.
* Need not pass marker code since it is stored in cinfo->unread_marker.
typedef JMETHOD(boolean, jpeg_marker_parser_method, (j_decompress_ptr cinfo));
/* Declarations for routines called by application.
* The JPP macro hides prototype parameters from compilers that can't cope.
* Note JPP requires double parentheses.
#define JPP(arglist) arglist
#define JPP(arglist) ()
/* Short forms of external names for systems with brain-damaged linkers.
* We shorten external names to be unique in the first six letters, which
* is good enough for all known systems.
* (If your compiler itself needs names to be unique in less than 15
* characters, you are out of luck. Get a better compiler.)
#define jpeg_std_error jStdError
#define jpeg_CreateCompress jCreaCompress
#define jpeg_CreateDecompress jCreaDecompress
#define jpeg_destroy_compress jDestCompress
#define jpeg_destroy_decompress jDestDecompress
#define jpeg_stdio_dest jStdDest
#define jpeg_stdio_src jStdSrc
#define jpeg_set_defaults jSetDefaults
#define jpeg_set_colorspace jSetColorspace
#define jpeg_default_colorspace jDefColorspace
#define jpeg_set_quality jSetQuality
#define jpeg_set_linear_quality jSetLQuality
#define jpeg_add_quant_table jAddQuantTable
#define jpeg_quality_scaling jQualityScaling
#define jpeg_simple_progression jSimProgress
#define jpeg_suppress_tables jSuppressTables
#define jpeg_alloc_quant_table jAlcQTable
#define jpeg_alloc_huff_table jAlcHTable
#define jpeg_start_compress jStrtCompress
#define jpeg_write_scanlines jWrtScanlines
#define jpeg_finish_compress jFinCompress
#define jpeg_write_raw_data jWrtRawData
#define jpeg_write_marker jWrtMarker
#define jpeg_write_m_header jWrtMHeader
#define jpeg_write_m_byte jWrtMByte
#define jpeg_write_tables jWrtTables
#define jpeg_read_header jReadHeader
#define jpeg_start_decompress jStrtDecompress
#define jpeg_read_scanlines jReadScanlines
#define jpeg_finish_decompress jFinDecompress
#define jpeg_read_raw_data jReadRawData
#define jpeg_has_multiple_scans jHasMultScn
#define jpeg_start_output jStrtOutput
#define jpeg_finish_output jFinOutput
#define jpeg_input_complete jInComplete
#define jpeg_new_colormap jNewCMap
#define jpeg_consume_input jConsumeInput
#define jpeg_calc_output_dimensions jCalcDimensions
#define jpeg_save_markers jSaveMarkers
#define jpeg_set_marker_processor jSetMarker
#define jpeg_read_coefficients jReadCoefs
#define jpeg_write_coefficients jWrtCoefs
#define jpeg_copy_critical_parameters jCopyCrit
#define jpeg_abort_compress jAbrtCompress
#define jpeg_abort_decompress jAbrtDecompress
#define jpeg_abort jAbort
#define jpeg_destroy jDestroy
#define jpeg_resync_to_restart jResyncRestart
/* Default error-management setup */
EXTERN(struct jpeg_error_mgr *) jpeg_std_error
JPP((struct jpeg_error_mgr * err));
/* Initialization of JPEG compression objects.
* jpeg_create_compress() and jpeg_create_decompress() are the exported
* names that applications should call. These expand to calls on
* jpeg_CreateCompress and jpeg_CreateDecompress with additional information
* passed for version mismatch checking.
* NB: you must set up the error-manager BEFORE calling jpeg_create_xxx.
#define jpeg_create_compress(cinfo) \
jpeg_CreateCompress((cinfo), JPEG_LIB_VERSION, \
(size_t) sizeof(struct jpeg_compress_struct))
#define jpeg_create_decompress(cinfo) \
jpeg_CreateDecompress((cinfo), JPEG_LIB_VERSION, \
(size_t) sizeof(struct jpeg_decompress_struct))
EXTERN(void) jpeg_CreateCompress JPP((j_compress_ptr cinfo,
int version, size_t structsize));
EXTERN(void) jpeg_CreateDecompress JPP((j_decompress_ptr cinfo,
int version, size_t structsize));
/* Destruction of JPEG compression objects */
EXTERN(void) jpeg_destroy_compress JPP((j_compress_ptr cinfo));
EXTERN(void) jpeg_destroy_decompress JPP((j_decompress_ptr cinfo));
/* Standard data source and destination managers: stdio streams. */
/* Caller is responsible for opening the file before and closing after. */
EXTERN(void) jpeg_stdio_dest JPP((j_compress_ptr cinfo, FILE * outfile));
EXTERN(void) jpeg_stdio_src JPP((j_decompress_ptr cinfo, FILE * infile));
/* Default parameter setup for compression */
EXTERN(void) jpeg_set_defaults JPP((j_compress_ptr cinfo));
/* Compression parameter setup aids */
EXTERN(void) jpeg_set_colorspace JPP((j_compress_ptr cinfo,
J_COLOR_SPACE colorspace));
EXTERN(void) jpeg_default_colorspace JPP((j_compress_ptr cinfo));
EXTERN(void) jpeg_set_quality JPP((j_compress_ptr cinfo, int quality,
boolean force_baseline));
EXTERN(void) jpeg_set_linear_quality JPP((j_compress_ptr cinfo,
int scale_factor,
boolean force_baseline));
EXTERN(void) jpeg_add_quant_table JPP((j_compress_ptr cinfo, int which_tbl,
const unsigned int *basic_table,
int scale_factor,
boolean force_baseline));
EXTERN(int) jpeg_quality_scaling JPP((int quality));
EXTERN(void) jpeg_simple_progression JPP((j_compress_ptr cinfo));
EXTERN(void) jpeg_suppress_tables JPP((j_compress_ptr cinfo,
boolean suppress));
EXTERN(JQUANT_TBL *) jpeg_alloc_quant_table JPP((j_common_ptr cinfo));
EXTERN(JHUFF_TBL *) jpeg_alloc_huff_table JPP((j_common_ptr cinfo));
/* Main entry points for compression */
EXTERN(void) jpeg_start_compress JPP((j_compress_ptr cinfo,
boolean write_all_tables));
EXTERN(JDIMENSION) jpeg_write_scanlines JPP((j_compress_ptr cinfo,
JSAMPARRAY scanlines,
JDIMENSION num_lines));
EXTERN(void) jpeg_finish_compress JPP((j_compress_ptr cinfo));
/* Replaces jpeg_write_scanlines when writing raw downsampled data. */
EXTERN(JDIMENSION) jpeg_write_raw_data JPP((j_compress_ptr cinfo,
JDIMENSION num_lines));
/* Write a special marker. See libjpeg.doc concerning safe usage. */
EXTERN(void) jpeg_write_marker
JPP((j_compress_ptr cinfo, int marker,
const JOCTET * dataptr, unsigned int datalen));
/* Same, but piecemeal. */
EXTERN(void) jpeg_write_m_header
JPP((j_compress_ptr cinfo, int marker, unsigned int datalen));
EXTERN(void) jpeg_write_m_byte
JPP((j_compress_ptr cinfo, int val));
/* Alternate compression function: just write an abbreviated table file */
EXTERN(void) jpeg_write_tables JPP((j_compress_ptr cinfo));
/* Decompression startup: read start of JPEG datastream to see what's there */
EXTERN(int) jpeg_read_header JPP((j_decompress_ptr cinfo,
boolean require_image));
/* Return value is one of: */
#define JPEG_SUSPENDED 0 /* Suspended due to lack of input data */
#define JPEG_HEADER_OK 1 /* Found valid image datastream */
#define JPEG_HEADER_TABLES_ONLY 2 /* Found valid table-specs-only datastream */
/* If you pass require_image = TRUE (normal case), you need not check for
* a TABLES_ONLY return code; an abbreviated file will cause an error exit.
* JPEG_SUSPENDED is only possible if you use a data source module that can
* give a suspension return (the stdio source module doesn't).
/* Main entry points for decompression */
EXTERN(boolean) jpeg_start_decompress JPP((j_decompress_ptr cinfo));
EXTERN(boolean) jpeg_start_tile_decompress JPP((j_decompress_ptr cinfo));
EXTERN(JDIMENSION) jpeg_read_scanlines JPP((j_decompress_ptr cinfo,
JSAMPARRAY scanlines,
JDIMENSION max_lines));
EXTERN(JDIMENSION) jpeg_read_scanlines_from JPP((j_decompress_ptr cinfo,
JSAMPARRAY scanlines,
int line_offset,
JDIMENSION max_lines));
EXTERN(JDIMENSION) jpeg_read_tile_scanline JPP((j_decompress_ptr cinfo,
huffman_index *index,
JSAMPARRAY scanlines));
EXTERN(void) jpeg_init_read_tile_scanline JPP((j_decompress_ptr cinfo,
huffman_index *index,
int *start_x, int *start_y,
int *width, int *height));
EXTERN(boolean) jpeg_finish_decompress JPP((j_decompress_ptr cinfo));
/* Replaces jpeg_read_scanlines when reading raw downsampled data. */
EXTERN(JDIMENSION) jpeg_read_raw_data JPP((j_decompress_ptr cinfo,
JDIMENSION max_lines));
/* Additional entry points for buffered-image mode. */
EXTERN(boolean) jpeg_has_multiple_scans JPP((j_decompress_ptr cinfo));
EXTERN(boolean) jpeg_start_output JPP((j_decompress_ptr cinfo,
int scan_number));
EXTERN(boolean) jpeg_finish_output JPP((j_decompress_ptr cinfo));
EXTERN(boolean) jpeg_input_complete JPP((j_decompress_ptr cinfo));
EXTERN(void) jpeg_new_colormap JPP((j_decompress_ptr cinfo));
EXTERN(int) jpeg_consume_input JPP((j_decompress_ptr cinfo));
/* Return value is one of: */
/* #define JPEG_SUSPENDED 0 Suspended due to lack of input data */
#define JPEG_REACHED_SOS 1 /* Reached start of new scan */
#define JPEG_REACHED_EOI 2 /* Reached end of image */
#define JPEG_ROW_COMPLETED 3 /* Completed one iMCU row */
#define JPEG_SCAN_COMPLETED 4 /* Completed last iMCU row of a scan */
/* Precalculate output dimensions for current decompression parameters. */
EXTERN(void) jpeg_calc_output_dimensions JPP((j_decompress_ptr cinfo));
/* Control saving of COM and APPn markers into marker_list. */
EXTERN(void) jpeg_save_markers
JPP((j_decompress_ptr cinfo, int marker_code,
unsigned int length_limit));
/* Install a special processing method for COM or APPn markers. */
EXTERN(void) jpeg_set_marker_processor
JPP((j_decompress_ptr cinfo, int marker_code,
jpeg_marker_parser_method routine));
/* Read or write raw DCT coefficients --- useful for lossless transcoding. */
EXTERN(jvirt_barray_ptr *) jpeg_read_coefficients JPP((j_decompress_ptr cinfo));
EXTERN(boolean) jpeg_build_huffman_index
JPP((j_decompress_ptr cinfo, huffman_index *index));
EXTERN(void) jpeg_write_coefficients JPP((j_compress_ptr cinfo,
jvirt_barray_ptr * coef_arrays));
EXTERN(void) jpeg_copy_critical_parameters JPP((j_decompress_ptr srcinfo,
j_compress_ptr dstinfo));
/* If you choose to abort compression or decompression before completing
* jpeg_finish_(de)compress, then you need to clean up to release memory,
* temporary files, etc. You can just call jpeg_destroy_(de)compress
* if you're done with the JPEG object, but if you want to clean it up and
* reuse it, call this:
EXTERN(void) jpeg_abort_compress JPP((j_compress_ptr cinfo));
EXTERN(void) jpeg_abort_decompress JPP((j_decompress_ptr cinfo));
/* Generic versions of jpeg_abort and jpeg_destroy that work on either
* flavor of JPEG object. These may be more convenient in some places.
EXTERN(void) jpeg_abort JPP((j_common_ptr cinfo));
EXTERN(void) jpeg_destroy JPP((j_common_ptr cinfo));
/* Default restart-marker-resync procedure for use by data source modules */
EXTERN(boolean) jpeg_resync_to_restart JPP((j_decompress_ptr cinfo,
int desired));
EXTERN(void) jpeg_configure_huffman_decoder(j_decompress_ptr cinfo,
huffman_offset_data offset);
EXTERN(void) jpeg_get_huffman_decoder_configuration(j_decompress_ptr cinfo,
huffman_offset_data *offset);
EXTERN(void) jpeg_create_huffman_index(j_decompress_ptr cinfo,
huffman_index *index);
EXTERN(void) jpeg_configure_huffman_index_scan(j_decompress_ptr cinfo,
huffman_index *index, int scan_no, int offset);
EXTERN(void) jpeg_destroy_huffman_index(huffman_index *index);
/* These marker codes are exported since applications and data source modules
* are likely to want to use them.
#define JPEG_RST0 0xD0 /* RST0 marker code */
#define JPEG_EOI 0xD9 /* EOI marker code */
#define JPEG_APP0 0xE0 /* APP0 marker code */
#define JPEG_COM 0xFE /* COM marker code */
/* If we have a brain-damaged compiler that emits warnings (or worse, errors)
* for structure definitions that are never filled in, keep it quiet by
* supplying dummy definitions for the various substructures.
#ifndef JPEG_INTERNALS /* will be defined in jpegint.h */
struct jvirt_sarray_control { long dummy; };
struct jvirt_barray_control { long dummy; };
struct jpeg_comp_master { long dummy; };
struct jpeg_c_main_controller { long dummy; };
struct jpeg_c_prep_controller { long dummy; };
struct jpeg_c_coef_controller { long dummy; };
struct jpeg_marker_writer { long dummy; };
struct jpeg_color_converter { long dummy; };
struct jpeg_downsampler { long dummy; };
struct jpeg_forward_dct { long dummy; };
struct jpeg_entropy_encoder { long dummy; };
struct jpeg_decomp_master { long dummy; };
struct jpeg_d_main_controller { long dummy; };
struct jpeg_d_coef_controller { long dummy; };
struct jpeg_d_post_controller { long dummy; };
struct jpeg_input_controller { long dummy; };
struct jpeg_marker_reader { long dummy; };
struct jpeg_entropy_decoder { long dummy; };
struct jpeg_inverse_dct { long dummy; };
struct jpeg_upsampler { long dummy; };
struct jpeg_color_deconverter { long dummy; };
struct jpeg_color_quantizer { long dummy; };
#endif /* JPEG_INTERNALS */
* The JPEG library modules define JPEG_INTERNALS before including this file.
* The internal structure declarations are read only when that is true.
* Applications using the library should not include jpegint.h, but may wish
* to include jerror.h.
#include "jpegint.h" /* fetch private declarations */
#include "jerror.h" /* fetch error codes too */
#endif /* JPEGLIB_H */