4
* Copyright (C) 1997-2009, 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.
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.
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.
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 */
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.
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.
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.)
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 JPEG format: the upper
55
* left corner of the selected region must fall on an iMCU boundary. If this
56
* does not hold for the given crop parameters, we silently move the upper left
57
* corner up and/or left to make it so, simultaneously increasing the region
58
* dimensions to keep the lower right crop corner unchanged. (Thus, the
59
* output image covers at least the requested region, but may cover more.)
61
* We also provide a lossless-resize option, which is kind of a lossless-crop
62
* operation in the DCT coefficient block domain - it discards higher-order
63
* coefficients and losslessly preserves lower-order coefficients of a
66
* Rotate/flip transform, resize, and crop can be requested together in a
67
* single invocation. The crop is applied last --- that is, the crop region
68
* is specified in terms of the destination image after transform/resize.
70
* We also offer a "force to grayscale" option, which simply discards the
71
* chrominance channels of a YCbCr image. This is lossless in the sense that
72
* the luminance channel is preserved exactly. It's not the same kind of
73
* thing as the rotate/flip transformations, but it's convenient to handle it
74
* as part of this package, mainly because the transformation routines have to
75
* be aware of the option to know how many components to work on.
79
/* Short forms of external names for systems with brain-damaged linkers. */
81
#ifdef NEED_SHORT_EXTERNAL_NAMES
82
#define jtransform_parse_crop_spec jTrParCrop
83
#define jtransform_request_workspace jTrRequest
84
#define jtransform_adjust_parameters jTrAdjust
85
#define jtransform_execute_transform jTrExec
86
#define jtransform_perfect_transform jTrPerfect
87
#define jcopy_markers_setup jCMrkSetup
88
#define jcopy_markers_execute jCMrkExec
89
#endif /* NEED_SHORT_EXTERNAL_NAMES */
93
* Codes for supported types of image transformations.
97
JXFORM_NONE, /* no transformation */
98
JXFORM_FLIP_H, /* horizontal flip */
99
JXFORM_FLIP_V, /* vertical flip */
100
JXFORM_TRANSPOSE, /* transpose across UL-to-LR axis */
101
JXFORM_TRANSVERSE, /* transpose across UR-to-LL axis */
102
JXFORM_ROT_90, /* 90-degree clockwise rotation */
103
JXFORM_ROT_180, /* 180-degree rotation */
104
JXFORM_ROT_270 /* 270-degree clockwise (or 90 ccw) */
108
* Codes for crop parameters, which can individually be unspecified,
109
* positive, or negative. (Negative width or height makes no sense, though.)
119
* Transform parameters struct.
120
* NB: application must not change any elements of this struct after
121
* calling jtransform_request_workspace.
125
/* Options: set by caller */
126
JXFORM_CODE transform; /* image transform operator */
127
boolean perfect; /* if TRUE, fail if partial MCUs are requested */
128
boolean trim; /* if TRUE, trim partial MCUs as needed */
129
boolean force_grayscale; /* if TRUE, convert color image to grayscale */
130
boolean crop; /* if TRUE, crop source image */
132
/* Crop parameters: application need not set these unless crop is TRUE.
133
* These can be filled in by jtransform_parse_crop_spec().
135
JDIMENSION crop_width; /* Width of selected region */
136
JCROP_CODE crop_width_set;
137
JDIMENSION crop_height; /* Height of selected region */
138
JCROP_CODE crop_height_set;
139
JDIMENSION crop_xoffset; /* X offset of selected region */
140
JCROP_CODE crop_xoffset_set; /* (negative measures from right edge) */
141
JDIMENSION crop_yoffset; /* Y offset of selected region */
142
JCROP_CODE crop_yoffset_set; /* (negative measures from bottom edge) */
144
/* Internal workspace: caller should not touch these */
145
int num_components; /* # of components in workspace */
146
jvirt_barray_ptr * workspace_coef_arrays; /* workspace for transformations */
147
JDIMENSION output_width; /* cropped destination dimensions */
148
JDIMENSION output_height;
149
JDIMENSION x_crop_offset; /* destination crop offsets measured in iMCUs */
150
JDIMENSION y_crop_offset;
151
int iMCU_sample_width; /* destination iMCU size */
152
int iMCU_sample_height;
153
} jpeg_transform_info;
156
#if TRANSFORMS_SUPPORTED
158
/* Parse a crop specification (written in X11 geometry style) */
159
EXTERN(boolean) jtransform_parse_crop_spec
160
JPP((jpeg_transform_info *info, const char *spec));
161
/* Request any required workspace */
162
EXTERN(boolean) jtransform_request_workspace
163
JPP((j_decompress_ptr srcinfo, jpeg_transform_info *info));
164
/* Adjust output image parameters */
165
EXTERN(jvirt_barray_ptr *) jtransform_adjust_parameters
166
JPP((j_decompress_ptr srcinfo, j_compress_ptr dstinfo,
167
jvirt_barray_ptr *src_coef_arrays,
168
jpeg_transform_info *info));
169
/* Execute the actual transformation, if any */
170
EXTERN(void) jtransform_execute_transform
171
JPP((j_decompress_ptr srcinfo, j_compress_ptr dstinfo,
172
jvirt_barray_ptr *src_coef_arrays,
173
jpeg_transform_info *info));
174
/* Determine whether lossless transformation is perfectly
175
* possible for a specified image and transformation.
177
EXTERN(boolean) jtransform_perfect_transform
178
JPP((JDIMENSION image_width, JDIMENSION image_height,
179
int MCU_width, int MCU_height,
180
JXFORM_CODE transform));
182
/* jtransform_execute_transform used to be called
183
* jtransform_execute_transformation, but some compilers complain about
184
* routine names that long. This macro is here to avoid breaking any
185
* old source code that uses the original name...
187
#define jtransform_execute_transformation jtransform_execute_transform
189
#endif /* TRANSFORMS_SUPPORTED */
193
* Support for copying optional markers from source to destination file.
197
JCOPYOPT_NONE, /* copy no optional markers */
198
JCOPYOPT_COMMENTS, /* copy only comment (COM) markers */
199
JCOPYOPT_ALL /* copy all optional markers */
202
#define JCOPYOPT_DEFAULT JCOPYOPT_COMMENTS /* recommended default */
204
/* Setup decompression object to save desired markers in memory */
205
EXTERN(void) jcopy_markers_setup
206
JPP((j_decompress_ptr srcinfo, JCOPY_OPTION option));
207
/* Copy markers saved in the given source object to the destination object */
208
EXTERN(void) jcopy_markers_execute
209
JPP((j_decompress_ptr srcinfo, j_compress_ptr dstinfo,
210
JCOPY_OPTION option));
added
removed
lib/libjpeg-80/transupp.h
