Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 1 | /* |
| 2 | * transupp.h |
| 3 | * |
Guido Vollbeding | 5829cb2 | 2012-01-15 00:00:00 +0000 | [diff] [blame] | 4 | * Copyright (C) 1997-2011, Thomas G. Lane, Guido Vollbeding. |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 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 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 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 | * |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 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.) |
Guido Vollbeding | 5829cb2 | 2012-01-15 00:00:00 +0000 | [diff] [blame] | 60 | * The adjustment of the region dimensions may be optionally disabled. |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 61 | * |
Guido Vollbeding | 989630f | 2010-01-10 00:00:00 +0000 | [diff] [blame] | 62 | * We also provide a lossless-resize option, which is kind of a lossless-crop |
| 63 | * operation in the DCT coefficient block domain - it discards higher-order |
| 64 | * coefficients and losslessly preserves lower-order coefficients of a |
| 65 | * sub-block. |
| 66 | * |
| 67 | * Rotate/flip transform, resize, and crop can be requested together in a |
| 68 | * single invocation. The crop is applied last --- that is, the crop region |
| 69 | * is specified in terms of the destination image after transform/resize. |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 70 | * |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 71 | * We also offer a "force to grayscale" option, which simply discards the |
| 72 | * chrominance channels of a YCbCr image. This is lossless in the sense that |
| 73 | * the luminance channel is preserved exactly. It's not the same kind of |
| 74 | * thing as the rotate/flip transformations, but it's convenient to handle it |
| 75 | * as part of this package, mainly because the transformation routines have to |
| 76 | * be aware of the option to know how many components to work on. |
| 77 | */ |
| 78 | |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 79 | |
| 80 | /* Short forms of external names for systems with brain-damaged linkers. */ |
| 81 | |
| 82 | #ifdef NEED_SHORT_EXTERNAL_NAMES |
| 83 | #define jtransform_parse_crop_spec jTrParCrop |
| 84 | #define jtransform_request_workspace jTrRequest |
| 85 | #define jtransform_adjust_parameters jTrAdjust |
| 86 | #define jtransform_execute_transform jTrExec |
| 87 | #define jtransform_perfect_transform jTrPerfect |
| 88 | #define jcopy_markers_setup jCMrkSetup |
| 89 | #define jcopy_markers_execute jCMrkExec |
| 90 | #endif /* NEED_SHORT_EXTERNAL_NAMES */ |
| 91 | |
| 92 | |
| 93 | /* |
| 94 | * Codes for supported types of image transformations. |
| 95 | */ |
| 96 | |
| 97 | typedef enum { |
| 98 | JXFORM_NONE, /* no transformation */ |
| 99 | JXFORM_FLIP_H, /* horizontal flip */ |
| 100 | JXFORM_FLIP_V, /* vertical flip */ |
| 101 | JXFORM_TRANSPOSE, /* transpose across UL-to-LR axis */ |
| 102 | JXFORM_TRANSVERSE, /* transpose across UR-to-LL axis */ |
| 103 | JXFORM_ROT_90, /* 90-degree clockwise rotation */ |
| 104 | JXFORM_ROT_180, /* 180-degree rotation */ |
| 105 | JXFORM_ROT_270 /* 270-degree clockwise (or 90 ccw) */ |
| 106 | } JXFORM_CODE; |
| 107 | |
| 108 | /* |
| 109 | * Codes for crop parameters, which can individually be unspecified, |
Guido Vollbeding | 5829cb2 | 2012-01-15 00:00:00 +0000 | [diff] [blame] | 110 | * positive or negative for xoffset or yoffset, |
| 111 | * positive or forced for width or height. |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 112 | */ |
| 113 | |
| 114 | typedef enum { |
Guido Vollbeding | 5829cb2 | 2012-01-15 00:00:00 +0000 | [diff] [blame] | 115 | JCROP_UNSET, |
| 116 | JCROP_POS, |
| 117 | JCROP_NEG, |
| 118 | JCROP_FORCE |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 119 | } JCROP_CODE; |
| 120 | |
| 121 | /* |
| 122 | * Transform parameters struct. |
| 123 | * NB: application must not change any elements of this struct after |
| 124 | * calling jtransform_request_workspace. |
| 125 | */ |
| 126 | |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 127 | typedef struct { |
| 128 | /* Options: set by caller */ |
| 129 | JXFORM_CODE transform; /* image transform operator */ |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 130 | boolean perfect; /* if TRUE, fail if partial MCUs are requested */ |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 131 | boolean trim; /* if TRUE, trim partial MCUs as needed */ |
| 132 | boolean force_grayscale; /* if TRUE, convert color image to grayscale */ |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 133 | boolean crop; /* if TRUE, crop source image */ |
DRC | ba5ea51 | 2011-03-04 03:20:34 +0000 | [diff] [blame] | 134 | boolean slow_hflip; /* For best performance, the JXFORM_FLIP_H transform |
| 135 | normally modifies the source coefficients in place. |
| 136 | Setting this to TRUE will instead use a slower, |
| 137 | double-buffered algorithm, which leaves the source |
| 138 | coefficients in tact (necessary if other transformed |
| 139 | images must be generated from the same set of |
| 140 | coefficients. */ |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 141 | |
| 142 | /* Crop parameters: application need not set these unless crop is TRUE. |
| 143 | * These can be filled in by jtransform_parse_crop_spec(). |
| 144 | */ |
| 145 | JDIMENSION crop_width; /* Width of selected region */ |
Guido Vollbeding | 5829cb2 | 2012-01-15 00:00:00 +0000 | [diff] [blame] | 146 | JCROP_CODE crop_width_set; /* (forced disables adjustment) */ |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 147 | JDIMENSION crop_height; /* Height of selected region */ |
Guido Vollbeding | 5829cb2 | 2012-01-15 00:00:00 +0000 | [diff] [blame] | 148 | JCROP_CODE crop_height_set; /* (forced disables adjustment) */ |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 149 | JDIMENSION crop_xoffset; /* X offset of selected region */ |
| 150 | JCROP_CODE crop_xoffset_set; /* (negative measures from right edge) */ |
| 151 | JDIMENSION crop_yoffset; /* Y offset of selected region */ |
| 152 | JCROP_CODE crop_yoffset_set; /* (negative measures from bottom edge) */ |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 153 | |
| 154 | /* Internal workspace: caller should not touch these */ |
| 155 | int num_components; /* # of components in workspace */ |
| 156 | jvirt_barray_ptr * workspace_coef_arrays; /* workspace for transformations */ |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 157 | JDIMENSION output_width; /* cropped destination dimensions */ |
| 158 | JDIMENSION output_height; |
| 159 | JDIMENSION x_crop_offset; /* destination crop offsets measured in iMCUs */ |
| 160 | JDIMENSION y_crop_offset; |
Guido Vollbeding | 989630f | 2010-01-10 00:00:00 +0000 | [diff] [blame] | 161 | int iMCU_sample_width; /* destination iMCU size */ |
| 162 | int iMCU_sample_height; |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 163 | } jpeg_transform_info; |
| 164 | |
| 165 | |
| 166 | #if TRANSFORMS_SUPPORTED |
| 167 | |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 168 | /* Parse a crop specification (written in X11 geometry style) */ |
| 169 | EXTERN(boolean) jtransform_parse_crop_spec |
| 170 | JPP((jpeg_transform_info *info, const char *spec)); |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 171 | /* Request any required workspace */ |
Guido Vollbeding | 989630f | 2010-01-10 00:00:00 +0000 | [diff] [blame] | 172 | EXTERN(boolean) jtransform_request_workspace |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 173 | JPP((j_decompress_ptr srcinfo, jpeg_transform_info *info)); |
| 174 | /* Adjust output image parameters */ |
| 175 | EXTERN(jvirt_barray_ptr *) jtransform_adjust_parameters |
| 176 | JPP((j_decompress_ptr srcinfo, j_compress_ptr dstinfo, |
| 177 | jvirt_barray_ptr *src_coef_arrays, |
| 178 | jpeg_transform_info *info)); |
| 179 | /* Execute the actual transformation, if any */ |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 180 | EXTERN(void) jtransform_execute_transform |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 181 | JPP((j_decompress_ptr srcinfo, j_compress_ptr dstinfo, |
| 182 | jvirt_barray_ptr *src_coef_arrays, |
| 183 | jpeg_transform_info *info)); |
Guido Vollbeding | 5996a25 | 2009-06-27 00:00:00 +0000 | [diff] [blame] | 184 | /* Determine whether lossless transformation is perfectly |
| 185 | * possible for a specified image and transformation. |
| 186 | */ |
| 187 | EXTERN(boolean) jtransform_perfect_transform |
| 188 | JPP((JDIMENSION image_width, JDIMENSION image_height, |
| 189 | int MCU_width, int MCU_height, |
| 190 | JXFORM_CODE transform)); |
| 191 | |
| 192 | /* jtransform_execute_transform used to be called |
| 193 | * jtransform_execute_transformation, but some compilers complain about |
| 194 | * routine names that long. This macro is here to avoid breaking any |
| 195 | * old source code that uses the original name... |
| 196 | */ |
| 197 | #define jtransform_execute_transformation jtransform_execute_transform |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 198 | |
| 199 | #endif /* TRANSFORMS_SUPPORTED */ |
| 200 | |
| 201 | |
| 202 | /* |
| 203 | * Support for copying optional markers from source to destination file. |
| 204 | */ |
| 205 | |
| 206 | typedef enum { |
| 207 | JCOPYOPT_NONE, /* copy no optional markers */ |
| 208 | JCOPYOPT_COMMENTS, /* copy only comment (COM) markers */ |
| 209 | JCOPYOPT_ALL /* copy all optional markers */ |
| 210 | } JCOPY_OPTION; |
| 211 | |
| 212 | #define JCOPYOPT_DEFAULT JCOPYOPT_COMMENTS /* recommended default */ |
| 213 | |
| 214 | /* Setup decompression object to save desired markers in memory */ |
| 215 | EXTERN(void) jcopy_markers_setup |
| 216 | JPP((j_decompress_ptr srcinfo, JCOPY_OPTION option)); |
| 217 | /* Copy markers saved in the given source object to the destination object */ |
| 218 | EXTERN(void) jcopy_markers_execute |
| 219 | JPP((j_decompress_ptr srcinfo, j_compress_ptr dstinfo, |
| 220 | JCOPY_OPTION option)); |