4 * Copyright (C) 1991-1997, Thomas G. Lane.
5 * Modified 1997-2009 by Guido Vollbeding.
6 * This file is part of the Independent JPEG Group's software.
7 * For conditions of distribution and use, see the accompanying README file.
9 * This file contains additional configuration options that customize the
10 * JPEG software for special applications or support machine-dependent
11 * optimizations. Most users will not need to touch this file.
16 * Define BITS_IN_JSAMPLE as either
17 * 8 for 8-bit sample values (the usual setting)
18 * 12 for 12-bit sample values
19 * Only 8 and 12 are legal data precisions for lossy JPEG according to the
20 * JPEG standard, and the IJG code does not support anything else!
21 * We do not support run-time selection of data precision, sorry.
24 #define BITS_IN_JSAMPLE 8 /* use 8 or 12 */
28 * Maximum number of components (color channels) allowed in JPEG image.
29 * To meet the letter of the JPEG spec, set this to 255. However, darn
30 * few applications need more than 4 channels (maybe 5 for CMYK + alpha
31 * mask). We recommend 10 as a reasonable compromise; use 4 if you are
32 * really short on memory. (Each allowed component costs a hundred or so
33 * bytes of storage, whether actually used in an image or not.)
36 #define MAX_COMPONENTS 10 /* maximum number of image components */
41 * You may need to change these if you have a machine with unusual data
42 * type sizes; for example, "char" not 8 bits, "short" not 16 bits,
43 * or "long" not 32 bits. We don't care whether "int" is 16 or 32 bits,
44 * but it had better be at least 16.
47 /* Representation of a single sample (pixel element value).
48 * We frequently allocate large arrays of these, so it's important to keep
49 * them small. But if you have memory to burn and access to char or short
50 * arrays is very slow on your hardware, you might want to change these.
53 #if BITS_IN_JSAMPLE == 8
54 /* JSAMPLE should be the smallest type that will hold the values 0..255.
55 * You can use a signed char by having GETJSAMPLE mask it with 0xFF.
58 #ifdef HAVE_UNSIGNED_CHAR
60 typedef unsigned char JSAMPLE;
61 #define GETJSAMPLE(value) ((int) (value))
63 #else /* not HAVE_UNSIGNED_CHAR */
66 #ifdef CHAR_IS_UNSIGNED
67 #define GETJSAMPLE(value) ((int) (value))
69 #define GETJSAMPLE(value) ((int) (value) & 0xFF)
70 #endif /* CHAR_IS_UNSIGNED */
72 #endif /* HAVE_UNSIGNED_CHAR */
74 #define MAXJSAMPLE 255
75 #define CENTERJSAMPLE 128
77 #endif /* BITS_IN_JSAMPLE == 8 */
80 #if BITS_IN_JSAMPLE == 12
81 /* JSAMPLE should be the smallest type that will hold the values 0..4095.
82 * On nearly all machines "short" will do nicely.
85 typedef short JSAMPLE;
86 #define GETJSAMPLE(value) ((int) (value))
88 #define MAXJSAMPLE 4095
89 #define CENTERJSAMPLE 2048
91 #endif /* BITS_IN_JSAMPLE == 12 */
94 /* Representation of a DCT frequency coefficient.
95 * This should be a signed value of at least 16 bits; "short" is usually OK.
96 * Again, we allocate large arrays of these, but you can change to int
97 * if you have memory to burn and "short" is really slow.
103 /* Compressed datastreams are represented as arrays of JOCTET.
104 * These must be EXACTLY 8 bits wide, at least once they are written to
105 * external storage. Note that when using the stdio data source/destination
106 * managers, this is also the data type passed to fread/fwrite.
109 #ifdef HAVE_UNSIGNED_CHAR
111 typedef unsigned char JOCTET;
112 #define GETJOCTET(value) (value)
114 #else /* not HAVE_UNSIGNED_CHAR */
117 #ifdef CHAR_IS_UNSIGNED
118 #define GETJOCTET(value) (value)
120 #define GETJOCTET(value) ((value) & 0xFF)
121 #endif /* CHAR_IS_UNSIGNED */
123 #endif /* HAVE_UNSIGNED_CHAR */
126 /* These typedefs are used for various table entries and so forth.
127 * They must be at least as wide as specified; but making them too big
128 * won't cost a huge amount of memory, so we don't provide special
129 * extraction code like we did for JSAMPLE. (In other words, these
130 * typedefs live at a different point on the speed/space tradeoff curve.)
133 /* UINT8 must hold at least the values 0..255. */
135 #ifdef HAVE_UNSIGNED_CHAR
136 typedef unsigned char UINT8;
137 #else /* not HAVE_UNSIGNED_CHAR */
138 #ifdef CHAR_IS_UNSIGNED
140 #else /* not CHAR_IS_UNSIGNED */
142 #endif /* CHAR_IS_UNSIGNED */
143 #endif /* HAVE_UNSIGNED_CHAR */
145 /* UINT16 must hold at least the values 0..65535. */
147 #ifdef HAVE_UNSIGNED_SHORT
148 typedef unsigned short UINT16;
149 #else /* not HAVE_UNSIGNED_SHORT */
150 typedef unsigned int UINT16;
151 #endif /* HAVE_UNSIGNED_SHORT */
153 /* INT16 must hold at least the values -32768..32767. */
155 #ifndef XMD_H /* X11/xmd.h correctly defines INT16 */
159 /* INT32 must hold at least signed 32-bit values. */
161 #ifndef XMD_H /* X11/xmd.h correctly defines INT32 */
162 #ifndef _BASETSD_H_ /* Microsoft defines it in basetsd.h */
163 #ifndef _BASETSD_H /* MinGW is slightly different */
164 #ifndef QGLOBAL_H /* Qt defines it in qglobal.h */
171 /* Datatype used for image dimensions. The JPEG standard only supports
172 * images up to 64K*64K due to 16-bit fields in SOF markers. Therefore
173 * "unsigned int" is sufficient on all machines. However, if you need to
174 * handle larger images and you don't mind deviating from the spec, you
175 * can change this datatype.
178 typedef unsigned int JDIMENSION;
180 #define JPEG_MAX_DIMENSION 65500L /* a tad under 64K to prevent overflows */
183 /* These macros are used in all function definitions and extern declarations.
184 * You could modify them if you need to change function linkage conventions;
185 * in particular, you'll need to do that to make the library a Windows DLL.
186 * Another application is to make all functions global for use with debuggers
187 * or code profilers that require it.
190 /* a function called through method pointers: */
191 #define METHODDEF(type) static type
192 /* a function used only in its module: */
193 #define LOCAL(type) static type
194 /* a function referenced thru EXTERNs: */
195 #define GLOBAL(type) type
196 /* a reference to a GLOBAL function: */
197 #define EXTERN(type) extern type
200 /* This macro is used to declare a "method", that is, a function pointer.
201 * We want to supply prototype parameters if the compiler can cope.
202 * Note that the arglist parameter must be parenthesized!
203 * Again, you can customize this if you need special linkage keywords.
206 #ifdef HAVE_PROTOTYPES
207 #define JMETHOD(type,methodname,arglist) type (*methodname) arglist
209 #define JMETHOD(type,methodname,arglist) type (*methodname) ()
213 /* Here is the pseudo-keyword for declaring pointers that must be "far"
214 * on 80x86 machines. Most of the specialized coding for 80x86 is handled
215 * by just saying "FAR *" where such a pointer is needed. In a few places
216 * explicit coding is needed; see uses of the NEED_FAR_POINTERS symbol.
220 #ifdef NEED_FAR_POINTERS
229 * On a few systems, type boolean and/or its values FALSE, TRUE may appear
230 * in standard header files. Or you may have conflicts with application-
231 * specific header files that you want to include together with these files.
232 * Defining HAVE_BOOLEAN before including jpeglib.h should make it work.
238 #ifndef FALSE /* in case these macros already exist */
239 #define FALSE 0 /* values of boolean */
247 * The remaining options affect code selection within the JPEG library,
248 * but they don't need to be visible to most applications using the library.
249 * To minimize application namespace pollution, the symbols won't be
250 * defined unless JPEG_INTERNALS or JPEG_INTERNAL_OPTIONS has been defined.
253 #ifdef JPEG_INTERNALS
254 #define JPEG_INTERNAL_OPTIONS
257 #ifdef JPEG_INTERNAL_OPTIONS
261 * These defines indicate whether to include various optional functions.
262 * Undefining some of these symbols will produce a smaller but less capable
263 * library. Note that you can leave certain source files out of the
264 * compilation/linking process if you've #undef'd the corresponding symbols.
265 * (You may HAVE to do that if your compiler doesn't like null source files.)
268 /* Capability options common to encoder and decoder: */
270 #define DCT_ISLOW_SUPPORTED /* slow but accurate integer algorithm */
271 #define DCT_IFAST_SUPPORTED /* faster, less accurate integer method */
272 #define DCT_FLOAT_SUPPORTED /* floating-point: accurate, fast on fast HW */
274 /* Encoder capability options: */
276 #define C_ARITH_CODING_SUPPORTED /* Arithmetic coding back end? */
277 #define C_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */
278 #define C_PROGRESSIVE_SUPPORTED /* Progressive JPEG? (Requires MULTISCAN)*/
279 #define DCT_SCALING_SUPPORTED /* Input rescaling via DCT? (Requires DCT_ISLOW)*/
280 #define ENTROPY_OPT_SUPPORTED /* Optimization of entropy coding parms? */
281 /* Note: if you selected 12-bit data precision, it is dangerous to turn off
282 * ENTROPY_OPT_SUPPORTED. The standard Huffman tables are only good for 8-bit
283 * precision, so jchuff.c normally uses entropy optimization to compute
284 * usable tables for higher precision. If you don't want to do optimization,
285 * you'll have to supply different default Huffman tables.
286 * The exact same statements apply for progressive JPEG: the default tables
287 * don't work for progressive mode. (This may get fixed, however.)
289 #define INPUT_SMOOTHING_SUPPORTED /* Input image smoothing option? */
291 /* Decoder capability options: */
293 #define D_ARITH_CODING_SUPPORTED /* Arithmetic coding back end? */
294 #define D_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */
295 #define D_PROGRESSIVE_SUPPORTED /* Progressive JPEG? (Requires MULTISCAN)*/
296 #define IDCT_SCALING_SUPPORTED /* Output rescaling via IDCT? */
297 #define SAVE_MARKERS_SUPPORTED /* jpeg_save_markers() needed? */
298 #define BLOCK_SMOOTHING_SUPPORTED /* Block smoothing? (Progressive only) */
299 #undef UPSAMPLE_SCALING_SUPPORTED /* Output rescaling at upsample stage? */
300 #define UPSAMPLE_MERGING_SUPPORTED /* Fast path for sloppy upsampling? */
301 #define QUANT_1PASS_SUPPORTED /* 1-pass color quantization? */
302 #define QUANT_2PASS_SUPPORTED /* 2-pass color quantization? */
304 /* more capability options later, no doubt */
308 * Ordering of RGB data in scanlines passed to or from the application.
309 * If your application wants to deal with data in the order B,G,R, just
310 * change these macros. You can also deal with formats such as R,G,B,X
311 * (one extra byte per pixel) by changing RGB_PIXELSIZE. Note that changing
312 * the offsets will also change the order in which colormap data is organized.
314 * 1. The sample applications cjpeg,djpeg do NOT support modified RGB formats.
315 * 2. These macros only affect RGB<=>YCbCr color conversion, so they are not
316 * useful if you are using JPEG color spaces other than YCbCr or grayscale.
317 * 3. The color quantizer modules will not behave desirably if RGB_PIXELSIZE
318 * is not 3 (they don't understand about dummy color components!). So you
319 * can't use color quantization if you change that value.
322 #define RGB_RED 0 /* Offset of Red in an RGB scanline element */
323 #define RGB_GREEN 1 /* Offset of Green */
324 #define RGB_BLUE 2 /* Offset of Blue */
325 #define RGB_PIXELSIZE 3 /* JSAMPLEs per RGB scanline element */
328 /* Definitions for speed-related optimizations. */
331 /* If your compiler supports inline functions, define INLINE
332 * as the inline keyword; otherwise define it as empty.
336 #ifdef __GNUC__ /* for instance, GNU C knows about inline */
337 #define INLINE __inline__
340 #define INLINE /* default is to define it as empty */
345 /* On some machines (notably 68000 series) "int" is 32 bits, but multiplying
346 * two 16-bit shorts is faster than multiplying two ints. Define MULTIPLIER
347 * as short on such a machine. MULTIPLIER must be at least 16 bits wide.
351 #define MULTIPLIER int /* type for fastest integer multiply */
355 /* FAST_FLOAT should be either float or double, whichever is done faster
356 * by your compiler. (Note that this type is only used in the floating point
357 * DCT routines, so it only matters if you've defined DCT_FLOAT_SUPPORTED.)
358 * Typically, float is faster in ANSI C compilers, while double is faster in
359 * pre-ANSI compilers (because they insist on converting to double anyway).
360 * The code below therefore chooses float if we have ANSI-style prototypes.
364 #ifdef HAVE_PROTOTYPES
365 #define FAST_FLOAT float
367 #define FAST_FLOAT double
371 #endif /* JPEG_INTERNAL_OPTIONS */