4 * This file was part of the Independent JPEG Group's software:
5 * Copyright (C) 1991-1997, Thomas G. Lane.
6 * Modified 1997-2009 by Guido Vollbeding.
7 * Lossless JPEG Modifications:
8 * Copyright (C) 1999, Ken Murchison.
9 * libjpeg-turbo Modifications:
10 * Copyright (C) 2009, 2011, 2014-2015, 2018, 2020, 2022, D. R. Commander.
11 * For conditions of distribution and use, see the accompanying README.ijg
14 * This file contains additional configuration options that customize the
15 * JPEG software for special applications or support machine-dependent
16 * optimizations. Most users will not need to touch this file.
21 * Maximum number of components (color channels) allowed in JPEG image.
22 * To meet the letter of Rec. ITU-T T.81 | ISO/IEC 10918-1, set this to 255.
23 * However, darn few applications need more than 4 channels (maybe 5 for CMYK +
24 * alpha mask). We recommend 10 as a reasonable compromise; use 4 if you are
25 * really short on memory. (Each allowed component costs a hundred or so
26 * bytes of storage, whether actually used in an image or not.)
29 #define MAX_COMPONENTS 10 /* maximum number of image components */
34 * You may need to change these if you have a machine with unusual data
35 * type sizes; for example, "char" not 8 bits, "short" not 16 bits,
36 * or "long" not 32 bits. We don't care whether "int" is 16 or 32 bits,
37 * but it had better be at least 16.
40 /* Representation of a single sample (pixel element value).
41 * We frequently allocate large arrays of these, so it's important to keep
42 * them small. But if you have memory to burn and access to char or short
43 * arrays is very slow on your hardware, you might want to change these.
46 /* JSAMPLE should be the smallest type that will hold the values 0..255. */
48 typedef unsigned char JSAMPLE;
49 #define GETJSAMPLE(value) ((int)(value))
51 #define MAXJSAMPLE 255
52 #define CENTERJSAMPLE 128
55 /* J12SAMPLE should be the smallest type that will hold the values 0..4095. */
57 typedef short J12SAMPLE;
59 #define MAXJ12SAMPLE 4095
60 #define CENTERJ12SAMPLE 2048
63 /* J16SAMPLE should be the smallest type that will hold the values 0..65535. */
65 typedef unsigned short J16SAMPLE;
67 #define MAXJ16SAMPLE 65535
68 #define CENTERJ16SAMPLE 32768
71 /* Representation of a DCT frequency coefficient.
72 * This should be a signed value of at least 16 bits; "short" is usually OK.
73 * Again, we allocate large arrays of these, but you can change to int
74 * if you have memory to burn and "short" is really slow.
80 /* Compressed datastreams are represented as arrays of JOCTET.
81 * These must be EXACTLY 8 bits wide, at least once they are written to
82 * external storage. Note that when using the stdio data source/destination
83 * managers, this is also the data type passed to fread/fwrite.
86 typedef unsigned char JOCTET;
87 #define GETJOCTET(value) (value)
90 /* These typedefs are used for various table entries and so forth.
91 * They must be at least as wide as specified; but making them too big
92 * won't cost a huge amount of memory, so we don't provide special
93 * extraction code like we did for JSAMPLE. (In other words, these
94 * typedefs live at a different point on the speed/space tradeoff curve.)
97 /* UINT8 must hold at least the values 0..255. */
99 typedef unsigned char UINT8;
101 /* UINT16 must hold at least the values 0..65535. */
103 typedef unsigned short UINT16;
105 /* INT16 must hold at least the values -32768..32767. */
107 #ifndef XMD_H /* X11/xmd.h correctly defines INT16 */
111 /* INT32 must hold at least signed 32-bit values.
113 * NOTE: The INT32 typedef dates back to libjpeg v5 (1994.) Integers were
114 * sometimes 16-bit back then (MS-DOS), which is why INT32 is typedef'd to
115 * long. It also wasn't common (or at least as common) in 1994 for INT32 to be
116 * defined by platform headers. Since then, however, INT32 is defined in
117 * several other common places:
119 * Xmd.h (X11 header) typedefs INT32 to int on 64-bit platforms and long on
120 * 32-bit platforms (i.e always a 32-bit signed type.)
122 * basetsd.h (Win32 header) typedefs INT32 to int (always a 32-bit signed type
123 * on modern platforms.)
125 * qglobal.h (Qt header) typedefs INT32 to int (always a 32-bit signed type on
128 * This is a recipe for conflict, since "long" and "int" aren't always
129 * compatible types. Since the definition of INT32 has technically been part
130 * of the libjpeg API for more than 20 years, we can't remove it, but we do not
131 * use it internally any longer. We instead define a separate type (JLONG)
132 * for internal use, which ensures that internal behavior will always be the
133 * same regardless of any external headers that may be included.
136 #ifndef XMD_H /* X11/xmd.h correctly defines INT32 */
137 #ifndef _BASETSD_H_ /* Microsoft defines it in basetsd.h */
138 #ifndef _BASETSD_H /* MinGW is slightly different */
139 #ifndef QGLOBAL_H /* Qt defines it in qglobal.h */
146 /* Datatype used for image dimensions. The JPEG standard only supports
147 * images up to 64K*64K due to 16-bit fields in SOF markers. Therefore
148 * "unsigned int" is sufficient on all machines. However, if you need to
149 * handle larger images and you don't mind deviating from the spec, you
150 * can change this datatype. (Note that changing this datatype will
151 * potentially require modifying the SIMD code. The x86-64 SIMD extensions,
152 * in particular, assume a 32-bit JDIMENSION.)
155 typedef unsigned int JDIMENSION;
157 #define JPEG_MAX_DIMENSION 65500L /* a tad under 64K to prevent overflows */
160 /* These macros are used in all function definitions and extern declarations.
161 * You could modify them if you need to change function linkage conventions;
162 * in particular, you'll need to do that to make the library a Windows DLL.
163 * Another application is to make all functions global for use with debuggers
164 * or code profilers that require it.
167 /* a function called through method pointers: */
168 #define METHODDEF(type) static type
169 /* a function used only in its module: */
170 #define LOCAL(type) static type
171 /* a function referenced thru EXTERNs: */
172 #define GLOBAL(type) type
173 /* a reference to a GLOBAL function: */
174 #define EXTERN(type) extern type
177 /* Originally, this macro was used as a way of defining function prototypes
178 * for both modern compilers as well as older compilers that did not support
179 * prototype parameters. libjpeg-turbo has never supported these older,
180 * non-ANSI compilers, but the macro is still included because there is some
181 * software out there that uses it.
184 #define JMETHOD(type, methodname, arglist) type (*methodname) arglist
187 /* libjpeg-turbo no longer supports platforms that have far symbols (MS-DOS),
188 * but again, some software relies on this macro.
196 * On a few systems, type boolean and/or its values FALSE, TRUE may appear
197 * in standard header files. Or you may have conflicts with application-
198 * specific header files that you want to include together with these files.
199 * Defining HAVE_BOOLEAN before including jpeglib.h should make it work.
205 #ifndef FALSE /* in case these macros already exist */
206 #define FALSE 0 /* values of boolean */
214 * The remaining options affect code selection within the JPEG library,
215 * but they don't need to be visible to most applications using the library.
216 * To minimize application namespace pollution, the symbols won't be
217 * defined unless JPEG_INTERNALS or JPEG_INTERNAL_OPTIONS has been defined.
220 #ifdef JPEG_INTERNALS
221 #define JPEG_INTERNAL_OPTIONS
224 #ifdef JPEG_INTERNAL_OPTIONS
228 * These defines indicate whether to include various optional functions.
229 * Undefining some of these symbols will produce a smaller but less capable
230 * library. Note that you can leave certain source files out of the
231 * compilation/linking process if you've #undef'd the corresponding symbols.
232 * (You may HAVE to do that if your compiler doesn't like null source files.)
235 /* Capability options common to encoder and decoder: */
237 #define DCT_ISLOW_SUPPORTED /* accurate integer method */
238 #define DCT_IFAST_SUPPORTED /* less accurate int method [legacy feature] */
239 #define DCT_FLOAT_SUPPORTED /* floating-point method [legacy feature] */
241 /* Encoder capability options: */
243 #define C_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */
244 #define C_PROGRESSIVE_SUPPORTED /* Progressive JPEG? (Requires MULTISCAN)*/
245 #define C_LOSSLESS_SUPPORTED /* Lossless JPEG? */
246 #define ENTROPY_OPT_SUPPORTED /* Optimization of entropy coding parms? */
247 /* Note: if you selected 12-bit data precision, it is dangerous to turn off
248 * ENTROPY_OPT_SUPPORTED. The standard Huffman tables are only good for 8-bit
249 * precision, so jchuff.c normally uses entropy optimization to compute
250 * usable tables for higher precision. If you don't want to do optimization,
251 * you'll have to supply different default Huffman tables.
252 * The exact same statements apply for progressive and lossless JPEG:
253 * the default tables don't work for progressive mode or lossless mode.
254 * (This may get fixed, however.)
256 #define INPUT_SMOOTHING_SUPPORTED /* Input image smoothing option? */
258 /* Decoder capability options: */
260 #define D_MULTISCAN_FILES_SUPPORTED /* Multiple-scan JPEG files? */
261 #define D_PROGRESSIVE_SUPPORTED /* Progressive JPEG? (Requires MULTISCAN)*/
262 #define D_LOSSLESS_SUPPORTED /* Lossless JPEG? */
263 #define SAVE_MARKERS_SUPPORTED /* jpeg_save_markers() needed? */
264 #define BLOCK_SMOOTHING_SUPPORTED /* Block smoothing? (Progressive only) */
265 #define IDCT_SCALING_SUPPORTED /* Output rescaling via IDCT? */
266 #undef UPSAMPLE_SCALING_SUPPORTED /* Output rescaling at upsample stage? */
267 #define UPSAMPLE_MERGING_SUPPORTED /* Fast path for sloppy upsampling? */
268 #define QUANT_1PASS_SUPPORTED /* 1-pass color quantization? */
269 #define QUANT_2PASS_SUPPORTED /* 2-pass color quantization? */
271 /* more capability options later, no doubt */
275 * The RGB_RED, RGB_GREEN, RGB_BLUE, and RGB_PIXELSIZE macros are a vestigial
276 * feature of libjpeg. The idea was that, if an application developer needed
277 * to compress from/decompress to a BGR/BGRX/RGBX/XBGR/XRGB buffer, they could
278 * change these macros, rebuild libjpeg, and link their application statically
279 * with it. In reality, few people ever did this, because there were some
280 * severe restrictions involved (cjpeg and djpeg no longer worked properly,
281 * compressing/decompressing RGB JPEGs no longer worked properly, and the color
282 * quantizer wouldn't work with pixel sizes other than 3.) Furthermore, since
283 * all of the O/S-supplied versions of libjpeg were built with the default
284 * values of RGB_RED, RGB_GREEN, RGB_BLUE, and RGB_PIXELSIZE, many applications
285 * have come to regard these values as immutable.
287 * The libjpeg-turbo colorspace extensions provide a much cleaner way of
288 * compressing from/decompressing to buffers with arbitrary component orders
289 * and pixel sizes. Thus, we do not support changing the values of RGB_RED,
290 * RGB_GREEN, RGB_BLUE, or RGB_PIXELSIZE. In addition to the restrictions
291 * listed above, changing these values will also break the SIMD extensions and
292 * the regression tests.
295 #define RGB_RED 0 /* Offset of Red in an RGB scanline element */
296 #define RGB_GREEN 1 /* Offset of Green */
297 #define RGB_BLUE 2 /* Offset of Blue */
298 #define RGB_PIXELSIZE 3 /* JSAMPLEs per RGB scanline element */
300 #define JPEG_NUMCS 17
302 #define EXT_RGB_RED 0
303 #define EXT_RGB_GREEN 1
304 #define EXT_RGB_BLUE 2
305 #define EXT_RGB_PIXELSIZE 3
307 #define EXT_RGBX_RED 0
308 #define EXT_RGBX_GREEN 1
309 #define EXT_RGBX_BLUE 2
310 #define EXT_RGBX_PIXELSIZE 4
312 #define EXT_BGR_RED 2
313 #define EXT_BGR_GREEN 1
314 #define EXT_BGR_BLUE 0
315 #define EXT_BGR_PIXELSIZE 3
317 #define EXT_BGRX_RED 2
318 #define EXT_BGRX_GREEN 1
319 #define EXT_BGRX_BLUE 0
320 #define EXT_BGRX_PIXELSIZE 4
322 #define EXT_XBGR_RED 3
323 #define EXT_XBGR_GREEN 2
324 #define EXT_XBGR_BLUE 1
325 #define EXT_XBGR_PIXELSIZE 4
327 #define EXT_XRGB_RED 1
328 #define EXT_XRGB_GREEN 2
329 #define EXT_XRGB_BLUE 3
330 #define EXT_XRGB_PIXELSIZE 4
332 static const int rgb_red[JPEG_NUMCS] = {
333 -1, -1, RGB_RED, -1, -1, -1, EXT_RGB_RED, EXT_RGBX_RED,
334 EXT_BGR_RED, EXT_BGRX_RED, EXT_XBGR_RED, EXT_XRGB_RED,
335 EXT_RGBX_RED, EXT_BGRX_RED, EXT_XBGR_RED, EXT_XRGB_RED,
339 static const int rgb_green[JPEG_NUMCS] = {
340 -1, -1, RGB_GREEN, -1, -1, -1, EXT_RGB_GREEN, EXT_RGBX_GREEN,
341 EXT_BGR_GREEN, EXT_BGRX_GREEN, EXT_XBGR_GREEN, EXT_XRGB_GREEN,
342 EXT_RGBX_GREEN, EXT_BGRX_GREEN, EXT_XBGR_GREEN, EXT_XRGB_GREEN,
346 static const int rgb_blue[JPEG_NUMCS] = {
347 -1, -1, RGB_BLUE, -1, -1, -1, EXT_RGB_BLUE, EXT_RGBX_BLUE,
348 EXT_BGR_BLUE, EXT_BGRX_BLUE, EXT_XBGR_BLUE, EXT_XRGB_BLUE,
349 EXT_RGBX_BLUE, EXT_BGRX_BLUE, EXT_XBGR_BLUE, EXT_XRGB_BLUE,
353 static const int rgb_pixelsize[JPEG_NUMCS] = {
354 -1, -1, RGB_PIXELSIZE, -1, -1, -1, EXT_RGB_PIXELSIZE, EXT_RGBX_PIXELSIZE,
355 EXT_BGR_PIXELSIZE, EXT_BGRX_PIXELSIZE, EXT_XBGR_PIXELSIZE, EXT_XRGB_PIXELSIZE,
356 EXT_RGBX_PIXELSIZE, EXT_BGRX_PIXELSIZE, EXT_XBGR_PIXELSIZE, EXT_XRGB_PIXELSIZE,
360 /* Definitions for speed-related optimizations. */
362 /* On some machines (notably 68000 series) "int" is 32 bits, but multiplying
363 * two 16-bit shorts is faster than multiplying two ints. Define MULTIPLIER
364 * as short on such a machine. MULTIPLIER must be at least 16 bits wide.
369 #define MULTIPLIER int /* type for fastest integer multiply */
371 #define MULTIPLIER short /* prefer 16-bit with SIMD for parellelism */
376 /* FAST_FLOAT should be either float or double, whichever is done faster
377 * by your compiler. (Note that this type is only used in the floating point
378 * DCT routines, so it only matters if you've defined DCT_FLOAT_SUPPORTED.)
382 #define FAST_FLOAT float
385 #endif /* JPEG_INTERNAL_OPTIONS */