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transupp.h
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1/*
2 * transupp.h
3 *
4 * Copyright (C) 1997-2019, Thomas G. Lane, Guido Vollbeding.
5 * This file is part of the Independent JPEG Group's software.
6 * For conditions of distribution and use, see the accompanying README file.
7 *
8 * This file contains declarations for image transformation routines and
9 * other utility code used by the jpegtran sample application. These are
10 * NOT part of the core JPEG library. But we keep these routines separate
11 * from jpegtran.c to ease the task of maintaining jpegtran-like programs
12 * that have other user interfaces.
13 *
14 * NOTE: all the routines declared here have very specific requirements
15 * about when they are to be executed during the reading and writing of the
16 * source and destination files. See the comments in transupp.c, or see
17 * jpegtran.c for an example of correct usage.
18 */
19
20/* If you happen not to want the image transform support, disable it here */
21#ifndef TRANSFORMS_SUPPORTED
22#define TRANSFORMS_SUPPORTED 1 /* 0 disables transform code */
23#endif
24
25/*
26 * Although rotating and flipping data expressed as DCT coefficients is not
27 * hard, there is an asymmetry in the JPEG format specification for images
28 * whose dimensions aren't multiples of the iMCU size. The right and bottom
29 * image edges are padded out to the next iMCU boundary with junk data; but
30 * no padding is possible at the top and left edges. If we were to flip
31 * the whole image including the pad data, then pad garbage would become
32 * visible at the top and/or left, and real pixels would disappear into the
33 * pad margins --- perhaps permanently, since encoders & decoders may not
34 * bother to preserve DCT blocks that appear to be completely outside the
35 * nominal image area. So, we have to exclude any partial iMCUs from the
36 * basic transformation.
37 *
38 * Transpose is the only transformation that can handle partial iMCUs at the
39 * right and bottom edges completely cleanly. flip_h can flip partial iMCUs
40 * at the bottom, but leaves any partial iMCUs at the right edge untouched.
41 * Similarly flip_v leaves any partial iMCUs at the bottom edge untouched.
42 * The other transforms are defined as combinations of these basic transforms
43 * and process edge blocks in a way that preserves the equivalence.
44 *
45 * The "trim" option causes untransformable partial iMCUs to be dropped;
46 * this is not strictly lossless, but it usually gives the best-looking
47 * result for odd-size images. Note that when this option is active,
48 * the expected mathematical equivalences between the transforms may not hold.
49 * (For example, -rot 270 -trim trims only the bottom edge, but -rot 90 -trim
50 * followed by -rot 180 -trim trims both edges.)
51 *
52 * We also offer a lossless-crop option, which discards data outside a given
53 * image region but losslessly preserves what is inside. Like the rotate and
54 * flip transforms, lossless crop is restricted by the current JPEG format: the
55 * upper left corner of the selected region must fall on an iMCU boundary. If
56 * this does not hold for the given crop parameters, we silently move the upper
57 * left corner up and/or left to make it so, simultaneously increasing the
58 * region dimensions to keep the lower right crop corner unchanged. (Thus, the
59 * output image covers at least the requested region, but may cover more.)
60 * The adjustment of the region dimensions may be optionally disabled.
61 *
62 * A complementary lossless-wipe option is provided to discard (gray out) data
63 * inside a given image region while losslessly preserving what is outside.
64 * Another option is lossless-drop, which replaces data at a given image
65 * position by another image. Both source images must have the same
66 * subsampling values. It is best if they also have the same quantization,
67 * otherwise quantization adaption occurs. The trim option can be used with
68 * the drop option to requantize the drop file to the source file.
69 *
70 * We also provide a lossless-resize option, which is kind of a lossless-crop
71 * operation in the DCT coefficient block domain - it discards higher-order
72 * coefficients and losslessly preserves lower-order coefficients of a
73 * sub-block.
74 *
75 * Rotate/flip transform, resize, and crop can be requested together in a
76 * single invocation. The crop is applied last --- that is, the crop region
77 * is specified in terms of the destination image after transform/resize.
78 *
79 * We also offer a "force to grayscale" option, which simply discards the
80 * chrominance channels of a YCbCr image. This is lossless in the sense that
81 * the luminance channel is preserved exactly. It's not the same kind of
82 * thing as the rotate/flip transformations, but it's convenient to handle it
83 * as part of this package, mainly because the transformation routines have to
84 * be aware of the option to know how many components to work on.
85 */
86
87
88/* Short forms of external names for systems with brain-damaged linkers. */
89
90#ifdef NEED_SHORT_EXTERNAL_NAMES
91#define jtransform_parse_crop_spec jTrParCrop
92#define jtransform_request_workspace jTrRequest
93#define jtransform_adjust_parameters jTrAdjust
94#define jtransform_execute_transform jTrExec
95#define jtransform_perfect_transform jTrPerfect
96#define jcopy_markers_setup jCMrkSetup
97#define jcopy_markers_execute jCMrkExec
98#endif /* NEED_SHORT_EXTERNAL_NAMES */
99
100
101/*
102 * Codes for supported types of image transformations.
103 */
104
105typedef enum {
106 JXFORM_NONE, /* no transformation */
107 JXFORM_FLIP_H, /* horizontal flip */
108 JXFORM_FLIP_V, /* vertical flip */
109 JXFORM_TRANSPOSE, /* transpose across UL-to-LR axis */
110 JXFORM_TRANSVERSE, /* transpose across UR-to-LL axis */
111 JXFORM_ROT_90, /* 90-degree clockwise rotation */
112 JXFORM_ROT_180, /* 180-degree rotation */
113 JXFORM_ROT_270, /* 270-degree clockwise (or 90 ccw) */
114 JXFORM_WIPE, /* wipe */
115 JXFORM_DROP /* drop */
117
118/*
119 * Codes for crop parameters, which can individually be unspecified,
120 * positive or negative for xoffset or yoffset,
121 * positive or force or reflect for width or height.
122 */
123
124typedef enum {
131
132/*
133 * Transform parameters struct.
134 * NB: application must not change any elements of this struct after
135 * calling jtransform_request_workspace.
136 */
137
138typedef struct {
139 /* Options: set by caller */
140 JXFORM_CODE transform; /* image transform operator */
141 boolean perfect; /* if TRUE, fail if partial MCUs are requested */
142 boolean trim; /* if TRUE, trim partial MCUs as needed */
143 boolean force_grayscale; /* if TRUE, convert color image to grayscale */
144 boolean crop; /* if TRUE, crop or wipe source image, or drop */
145
146 /* Crop parameters: application need not set these unless crop is TRUE.
147 * These can be filled in by jtransform_parse_crop_spec().
148 */
149 JDIMENSION crop_width; /* Width of selected region */
150 JCROP_CODE crop_width_set; /* (force disables adjustment) */
151 JDIMENSION crop_height; /* Height of selected region */
152 JCROP_CODE crop_height_set; /* (force disables adjustment) */
153 JDIMENSION crop_xoffset; /* X offset of selected region */
154 JCROP_CODE crop_xoffset_set; /* (negative measures from right edge) */
155 JDIMENSION crop_yoffset; /* Y offset of selected region */
156 JCROP_CODE crop_yoffset_set; /* (negative measures from bottom edge) */
157
158 /* Drop parameters: set by caller for drop request */
161
162 /* Internal workspace: caller should not touch these */
163 int num_components; /* # of components in workspace */
164 jvirt_barray_ptr * workspace_coef_arrays; /* workspace for transformations */
165 JDIMENSION output_width; /* cropped destination dimensions */
167 JDIMENSION x_crop_offset; /* destination crop offsets measured in iMCUs */
169 JDIMENSION drop_width; /* drop/wipe dimensions measured in iMCUs */
171 int iMCU_sample_width; /* destination iMCU size */
174
175
176#if TRANSFORMS_SUPPORTED
177
178/* Parse a crop specification (written in X11 geometry style) */
179EXTERN(boolean) jtransform_parse_crop_spec
180 JPP((jpeg_transform_info *info, const char *spec));
181/* Request any required workspace */
182EXTERN(boolean) jtransform_request_workspace
184/* Adjust output image parameters */
185EXTERN(jvirt_barray_ptr *) jtransform_adjust_parameters
187 jvirt_barray_ptr *src_coef_arrays,
189/* Execute the actual transformation, if any */
190EXTERN(void) jtransform_execute_transform
192 jvirt_barray_ptr *src_coef_arrays,
194/* Determine whether lossless transformation is perfectly
195 * possible for a specified image and transformation.
196 */
197EXTERN(boolean) jtransform_perfect_transform
199 int MCU_width, int MCU_height,
201
202/* jtransform_execute_transform used to be called
203 * jtransform_execute_transformation, but some compilers complain about
204 * routine names that long. This macro is here to avoid breaking any
205 * old source code that uses the original name...
206 */
207#define jtransform_execute_transformation jtransform_execute_transform
208
209#endif /* TRANSFORMS_SUPPORTED */
210
211
212/*
213 * Support for copying optional markers from source to destination file.
214 */
215
216typedef enum {
217 JCOPYOPT_NONE, /* copy no optional markers */
218 JCOPYOPT_COMMENTS, /* copy only comment (COM) markers */
219 JCOPYOPT_ALL /* copy all optional markers */
221
222#define JCOPYOPT_DEFAULT JCOPYOPT_COMMENTS /* recommended default */
223
224/* Setup decompression object to save desired markers in memory */
227/* Copy markers saved in the given source object to the destination object */
GLuint GLenum GLenum transform
Definition: glext.h:9407
unsigned int JDIMENSION
Definition: jmorecfg.h:229
#define JPP(arglist)
Definition: jpeglib.h:877
int image_height
int image_width
JDIMENSION crop_height
Definition: transupp.h:151
JCROP_CODE crop_yoffset_set
Definition: transupp.h:156
boolean force_grayscale
Definition: transupp.h:143
JDIMENSION output_height
Definition: transupp.h:166
JCROP_CODE crop_height_set
Definition: transupp.h:152
JDIMENSION drop_height
Definition: transupp.h:170
j_decompress_ptr drop_ptr
Definition: transupp.h:159
JDIMENSION drop_width
Definition: transupp.h:169
JDIMENSION crop_yoffset
Definition: transupp.h:155
jvirt_barray_ptr * workspace_coef_arrays
Definition: transupp.h:164
JDIMENSION crop_xoffset
Definition: transupp.h:153
JCROP_CODE crop_xoffset_set
Definition: transupp.h:154
JCROP_CODE crop_width_set
Definition: transupp.h:150
JXFORM_CODE transform
Definition: transupp.h:140
JDIMENSION crop_width
Definition: transupp.h:149
JDIMENSION output_width
Definition: transupp.h:165
JDIMENSION x_crop_offset
Definition: transupp.h:167
JDIMENSION y_crop_offset
Definition: transupp.h:168
jvirt_barray_ptr * drop_coef_arrays
Definition: transupp.h:160
Definition: getopt.h:109
jcopy_markers_setup(j_decompress_ptr srcinfo, JCOPY_OPTION option)
Definition: transupp.c:2367
jcopy_markers_execute(j_decompress_ptr srcinfo, j_compress_ptr dstinfo, JCOPY_OPTION option)
Definition: transupp.c:2392
JXFORM_CODE
Definition: transupp.h:105
@ JXFORM_DROP
Definition: transupp.h:115
@ JXFORM_FLIP_H
Definition: transupp.h:107
@ JXFORM_ROT_270
Definition: transupp.h:113
@ JXFORM_TRANSPOSE
Definition: transupp.h:109
@ JXFORM_TRANSVERSE
Definition: transupp.h:110
@ JXFORM_NONE
Definition: transupp.h:106
@ JXFORM_WIPE
Definition: transupp.h:114
@ JXFORM_ROT_180
Definition: transupp.h:112
@ JXFORM_FLIP_V
Definition: transupp.h:108
@ JXFORM_ROT_90
Definition: transupp.h:111
EXTERN(void) jcopy_markers_setup JPP((j_decompress_ptr srcinfo
JCOPY_OPTION
Definition: transupp.h:216
@ JCOPYOPT_NONE
Definition: transupp.h:217
@ JCOPYOPT_COMMENTS
Definition: transupp.h:218
@ JCOPYOPT_ALL
Definition: transupp.h:219
j_compress_ptr dstinfo
Definition: transupp.h:229
JCROP_CODE
Definition: transupp.h:124
@ JCROP_FORCE
Definition: transupp.h:128
@ JCROP_POS
Definition: transupp.h:126
@ JCROP_UNSET
Definition: transupp.h:125
@ JCROP_NEG
Definition: transupp.h:127
@ JCROP_REFLECT
Definition: transupp.h:129