1 // Copyright 2011 Google Inc. All Rights Reserved. 2 // 3 // Use of this source code is governed by a BSD-style license 4 // that can be found in the COPYING file in the root of the source 5 // tree. An additional intellectual property rights grant can be found 6 // in the file PATENTS. All contributing project authors may 7 // be found in the AUTHORS file in the root of the source tree. 8 // ----------------------------------------------------------------------------- 9 // 10 // WebP encoder: main interface 11 // 12 // Author: Skal (pascal.massimino (at) gmail.com) 13 14 #ifndef WEBP_WEBP_ENCODE_H_ 15 #define WEBP_WEBP_ENCODE_H_ 16 17 #include "./types.h" 18 19 #ifdef __cplusplus 20 extern "C" { 21 #endif 22 23 #define WEBP_ENCODER_ABI_VERSION 0x020e // MAJOR(8b) + MINOR(8b) 24 25 // Note: forward declaring enumerations is not allowed in (strict) C and C++, 26 // the types are left here for reference. 27 // typedef enum WebPImageHint WebPImageHint; 28 // typedef enum WebPEncCSP WebPEncCSP; 29 // typedef enum WebPPreset WebPPreset; 30 // typedef enum WebPEncodingError WebPEncodingError; 31 typedef struct WebPConfig WebPConfig; 32 typedef struct WebPPicture WebPPicture; // main structure for I/O 33 typedef struct WebPAuxStats WebPAuxStats; 34 typedef struct WebPMemoryWriter WebPMemoryWriter; 35 36 // Return the encoder's version number, packed in hexadecimal using 8bits for 37 // each of major/minor/revision. E.g: v2.5.7 is 0x020507. 38 WEBP_EXTERN int WebPGetEncoderVersion(void); 39 40 //------------------------------------------------------------------------------ 41 // One-stop-shop call! No questions asked: 42 43 // Returns the size of the compressed data (pointed to by *output), or 0 if 44 // an error occurred. The compressed data must be released by the caller 45 // using the call 'WebPFree(*output)'. 46 // These functions compress using the lossy format, and the quality_factor 47 // can go from 0 (smaller output, lower quality) to 100 (best quality, 48 // larger output). 49 WEBP_EXTERN size_t WebPEncodeRGB(const uint8_t* rgb, 50 int width, int height, int stride, 51 float quality_factor, uint8_t** output); 52 WEBP_EXTERN size_t WebPEncodeBGR(const uint8_t* bgr, 53 int width, int height, int stride, 54 float quality_factor, uint8_t** output); 55 WEBP_EXTERN size_t WebPEncodeRGBA(const uint8_t* rgba, 56 int width, int height, int stride, 57 float quality_factor, uint8_t** output); 58 WEBP_EXTERN size_t WebPEncodeBGRA(const uint8_t* bgra, 59 int width, int height, int stride, 60 float quality_factor, uint8_t** output); 61 62 // These functions are the equivalent of the above, but compressing in a 63 // lossless manner. Files are usually larger than lossy format, but will 64 // not suffer any compression loss. 65 WEBP_EXTERN size_t WebPEncodeLosslessRGB(const uint8_t* rgb, 66 int width, int height, int stride, 67 uint8_t** output); 68 WEBP_EXTERN size_t WebPEncodeLosslessBGR(const uint8_t* bgr, 69 int width, int height, int stride, 70 uint8_t** output); 71 WEBP_EXTERN size_t WebPEncodeLosslessRGBA(const uint8_t* rgba, 72 int width, int height, int stride, 73 uint8_t** output); 74 WEBP_EXTERN size_t WebPEncodeLosslessBGRA(const uint8_t* bgra, 75 int width, int height, int stride, 76 uint8_t** output); 77 78 // Releases memory returned by the WebPEncode*() functions above. 79 WEBP_EXTERN void WebPFree(void* ptr); 80 81 //------------------------------------------------------------------------------ 82 // Coding parameters 83 84 // Image characteristics hint for the underlying encoder. 85 typedef enum WebPImageHint { 86 WEBP_HINT_DEFAULT = 0, // default preset. 87 WEBP_HINT_PICTURE, // digital picture, like portrait, inner shot 88 WEBP_HINT_PHOTO, // outdoor photograph, with natural lighting 89 WEBP_HINT_GRAPH, // Discrete tone image (graph, map-tile etc). 90 WEBP_HINT_LAST 91 } WebPImageHint; 92 93 // Compression parameters. 94 struct WebPConfig { 95 int lossless; // Lossless encoding (0=lossy(default), 1=lossless). 96 float quality; // between 0 and 100. For lossy, 0 gives the smallest 97 // size and 100 the largest. For lossless, this 98 // parameter is the amount of effort put into the 99 // compression: 0 is the fastest but gives larger 100 // files compared to the slowest, but best, 100. 101 int method; // quality/speed trade-off (0=fast, 6=slower-better) 102 103 WebPImageHint image_hint; // Hint for image type (lossless only for now). 104 105 int target_size; // if non-zero, set the desired target size in bytes. 106 // Takes precedence over the 'compression' parameter. 107 float target_PSNR; // if non-zero, specifies the minimal distortion to 108 // try to achieve. Takes precedence over target_size. 109 int segments; // maximum number of segments to use, in [1..4] 110 int sns_strength; // Spatial Noise Shaping. 0=off, 100=maximum. 111 int filter_strength; // range: [0 = off .. 100 = strongest] 112 int filter_sharpness; // range: [0 = off .. 7 = least sharp] 113 int filter_type; // filtering type: 0 = simple, 1 = strong (only used 114 // if filter_strength > 0 or autofilter > 0) 115 int autofilter; // Auto adjust filter's strength [0 = off, 1 = on] 116 int alpha_compression; // Algorithm for encoding the alpha plane (0 = none, 117 // 1 = compressed with WebP lossless). Default is 1. 118 int alpha_filtering; // Predictive filtering method for alpha plane. 119 // 0: none, 1: fast, 2: best. Default if 1. 120 int alpha_quality; // Between 0 (smallest size) and 100 (lossless). 121 // Default is 100. 122 int pass; // number of entropy-analysis passes (in [1..10]). 123 124 int show_compressed; // if true, export the compressed picture back. 125 // In-loop filtering is not applied. 126 int preprocessing; // preprocessing filter: 127 // 0=none, 1=segment-smooth, 2=pseudo-random dithering 128 int partitions; // log2(number of token partitions) in [0..3]. Default 129 // is set to 0 for easier progressive decoding. 130 int partition_limit; // quality degradation allowed to fit the 512k limit 131 // on prediction modes coding (0: no degradation, 132 // 100: maximum possible degradation). 133 int emulate_jpeg_size; // If true, compression parameters will be remapped 134 // to better match the expected output size from 135 // JPEG compression. Generally, the output size will 136 // be similar but the degradation will be lower. 137 int thread_level; // If non-zero, try and use multi-threaded encoding. 138 int low_memory; // If set, reduce memory usage (but increase CPU use). 139 140 int near_lossless; // Near lossless encoding [0 = max loss .. 100 = off 141 // (default)]. 142 int exact; // if non-zero, preserve the exact RGB values under 143 // transparent area. Otherwise, discard this invisible 144 // RGB information for better compression. The default 145 // value is 0. 146 147 int use_delta_palette; // reserved for future lossless feature 148 int use_sharp_yuv; // if needed, use sharp (and slow) RGB->YUV conversion 149 150 uint32_t pad[2]; // padding for later use 151 }; 152 153 // Enumerate some predefined settings for WebPConfig, depending on the type 154 // of source picture. These presets are used when calling WebPConfigPreset(). 155 typedef enum WebPPreset { 156 WEBP_PRESET_DEFAULT = 0, // default preset. 157 WEBP_PRESET_PICTURE, // digital picture, like portrait, inner shot 158 WEBP_PRESET_PHOTO, // outdoor photograph, with natural lighting 159 WEBP_PRESET_DRAWING, // hand or line drawing, with high-contrast details 160 WEBP_PRESET_ICON, // small-sized colorful images 161 WEBP_PRESET_TEXT // text-like 162 } WebPPreset; 163 164 // Internal, version-checked, entry point 165 WEBP_EXTERN int WebPConfigInitInternal(WebPConfig*, WebPPreset, float, int); 166 167 // Should always be called, to initialize a fresh WebPConfig structure before 168 // modification. Returns false in case of version mismatch. WebPConfigInit() 169 // must have succeeded before using the 'config' object. 170 // Note that the default values are lossless=0 and quality=75. 171 static WEBP_INLINE int WebPConfigInit(WebPConfig* config) { 172 return WebPConfigInitInternal(config, WEBP_PRESET_DEFAULT, 75.f, 173 WEBP_ENCODER_ABI_VERSION); 174 } 175 176 // This function will initialize the configuration according to a predefined 177 // set of parameters (referred to by 'preset') and a given quality factor. 178 // This function can be called as a replacement to WebPConfigInit(). Will 179 // return false in case of error. 180 static WEBP_INLINE int WebPConfigPreset(WebPConfig* config, 181 WebPPreset preset, float quality) { 182 return WebPConfigInitInternal(config, preset, quality, 183 WEBP_ENCODER_ABI_VERSION); 184 } 185 186 // Activate the lossless compression mode with the desired efficiency level 187 // between 0 (fastest, lowest compression) and 9 (slower, best compression). 188 // A good default level is '6', providing a fair tradeoff between compression 189 // speed and final compressed size. 190 // This function will overwrite several fields from config: 'method', 'quality' 191 // and 'lossless'. Returns false in case of parameter error. 192 WEBP_EXTERN int WebPConfigLosslessPreset(WebPConfig* config, int level); 193 194 // Returns true if 'config' is non-NULL and all configuration parameters are 195 // within their valid ranges. 196 WEBP_EXTERN int WebPValidateConfig(const WebPConfig* config); 197 198 //------------------------------------------------------------------------------ 199 // Input / Output 200 // Structure for storing auxiliary statistics. 201 202 struct WebPAuxStats { 203 int coded_size; // final size 204 205 float PSNR[5]; // peak-signal-to-noise ratio for Y/U/V/All/Alpha 206 int block_count[3]; // number of intra4/intra16/skipped macroblocks 207 int header_bytes[2]; // approximate number of bytes spent for header 208 // and mode-partition #0 209 int residual_bytes[3][4]; // approximate number of bytes spent for 210 // DC/AC/uv coefficients for each (0..3) segments. 211 int segment_size[4]; // number of macroblocks in each segments 212 int segment_quant[4]; // quantizer values for each segments 213 int segment_level[4]; // filtering strength for each segments [0..63] 214 215 int alpha_data_size; // size of the transparency data 216 int layer_data_size; // size of the enhancement layer data 217 218 // lossless encoder statistics 219 uint32_t lossless_features; // bit0:predictor bit1:cross-color transform 220 // bit2:subtract-green bit3:color indexing 221 int histogram_bits; // number of precision bits of histogram 222 int transform_bits; // precision bits for transform 223 int cache_bits; // number of bits for color cache lookup 224 int palette_size; // number of color in palette, if used 225 int lossless_size; // final lossless size 226 int lossless_hdr_size; // lossless header (transform, huffman etc) size 227 int lossless_data_size; // lossless image data size 228 229 uint32_t pad[2]; // padding for later use 230 }; 231 232 // Signature for output function. Should return true if writing was successful. 233 // data/data_size is the segment of data to write, and 'picture' is for 234 // reference (and so one can make use of picture->custom_ptr). 235 typedef int (*WebPWriterFunction)(const uint8_t* data, size_t data_size, 236 const WebPPicture* picture); 237 238 // WebPMemoryWrite: a special WebPWriterFunction that writes to memory using 239 // the following WebPMemoryWriter object (to be set as a custom_ptr). 240 struct WebPMemoryWriter { 241 uint8_t* mem; // final buffer (of size 'max_size', larger than 'size'). 242 size_t size; // final size 243 size_t max_size; // total capacity 244 uint32_t pad[1]; // padding for later use 245 }; 246 247 // The following must be called first before any use. 248 WEBP_EXTERN void WebPMemoryWriterInit(WebPMemoryWriter* writer); 249 250 // The following must be called to deallocate writer->mem memory. The 'writer' 251 // object itself is not deallocated. 252 WEBP_EXTERN void WebPMemoryWriterClear(WebPMemoryWriter* writer); 253 // The custom writer to be used with WebPMemoryWriter as custom_ptr. Upon 254 // completion, writer.mem and writer.size will hold the coded data. 255 // writer.mem must be freed by calling WebPMemoryWriterClear. 256 WEBP_EXTERN int WebPMemoryWrite(const uint8_t* data, size_t data_size, 257 const WebPPicture* picture); 258 259 // Progress hook, called from time to time to report progress. It can return 260 // false to request an abort of the encoding process, or true otherwise if 261 // everything is OK. 262 typedef int (*WebPProgressHook)(int percent, const WebPPicture* picture); 263 264 // Color spaces. 265 typedef enum WebPEncCSP { 266 // chroma sampling 267 WEBP_YUV420 = 0, // 4:2:0 268 WEBP_YUV420A = 4, // alpha channel variant 269 WEBP_CSP_UV_MASK = 3, // bit-mask to get the UV sampling factors 270 WEBP_CSP_ALPHA_BIT = 4 // bit that is set if alpha is present 271 } WebPEncCSP; 272 273 // Encoding error conditions. 274 typedef enum WebPEncodingError { 275 VP8_ENC_OK = 0, 276 VP8_ENC_ERROR_OUT_OF_MEMORY, // memory error allocating objects 277 VP8_ENC_ERROR_BITSTREAM_OUT_OF_MEMORY, // memory error while flushing bits 278 VP8_ENC_ERROR_NULL_PARAMETER, // a pointer parameter is NULL 279 VP8_ENC_ERROR_INVALID_CONFIGURATION, // configuration is invalid 280 VP8_ENC_ERROR_BAD_DIMENSION, // picture has invalid width/height 281 VP8_ENC_ERROR_PARTITION0_OVERFLOW, // partition is bigger than 512k 282 VP8_ENC_ERROR_PARTITION_OVERFLOW, // partition is bigger than 16M 283 VP8_ENC_ERROR_BAD_WRITE, // error while flushing bytes 284 VP8_ENC_ERROR_FILE_TOO_BIG, // file is bigger than 4G 285 VP8_ENC_ERROR_USER_ABORT, // abort request by user 286 VP8_ENC_ERROR_LAST // list terminator. always last. 287 } WebPEncodingError; 288 289 // maximum width/height allowed (inclusive), in pixels 290 #define WEBP_MAX_DIMENSION 16383 291 292 // Main exchange structure (input samples, output bytes, statistics) 293 struct WebPPicture { 294 // INPUT 295 ////////////// 296 // Main flag for encoder selecting between ARGB or YUV input. 297 // It is recommended to use ARGB input (*argb, argb_stride) for lossless 298 // compression, and YUV input (*y, *u, *v, etc.) for lossy compression 299 // since these are the respective native colorspace for these formats. 300 int use_argb; 301 302 // YUV input (mostly used for input to lossy compression) 303 WebPEncCSP colorspace; // colorspace: should be YUV420 for now (=Y'CbCr). 304 int width, height; // dimensions (less or equal to WEBP_MAX_DIMENSION) 305 uint8_t *y, *u, *v; // pointers to luma/chroma planes. 306 int y_stride, uv_stride; // luma/chroma strides. 307 uint8_t* a; // pointer to the alpha plane 308 int a_stride; // stride of the alpha plane 309 uint32_t pad1[2]; // padding for later use 310 311 // ARGB input (mostly used for input to lossless compression) 312 uint32_t* argb; // Pointer to argb (32 bit) plane. 313 int argb_stride; // This is stride in pixels units, not bytes. 314 uint32_t pad2[3]; // padding for later use 315 316 // OUTPUT 317 /////////////// 318 // Byte-emission hook, to store compressed bytes as they are ready. 319 WebPWriterFunction writer; // can be NULL 320 void* custom_ptr; // can be used by the writer. 321 322 // map for extra information (only for lossy compression mode) 323 int extra_info_type; // 1: intra type, 2: segment, 3: quant 324 // 4: intra-16 prediction mode, 325 // 5: chroma prediction mode, 326 // 6: bit cost, 7: distortion 327 uint8_t* extra_info; // if not NULL, points to an array of size 328 // ((width + 15) / 16) * ((height + 15) / 16) that 329 // will be filled with a macroblock map, depending 330 // on extra_info_type. 331 332 // STATS AND REPORTS 333 /////////////////////////// 334 // Pointer to side statistics (updated only if not NULL) 335 WebPAuxStats* stats; 336 337 // Error code for the latest error encountered during encoding 338 WebPEncodingError error_code; 339 340 // If not NULL, report progress during encoding. 341 WebPProgressHook progress_hook; 342 343 void* user_data; // this field is free to be set to any value and 344 // used during callbacks (like progress-report e.g.). 345 346 uint32_t pad3[3]; // padding for later use 347 348 // Unused for now 349 uint8_t *pad4, *pad5; 350 uint32_t pad6[8]; // padding for later use 351 352 // PRIVATE FIELDS 353 //////////////////// 354 void* memory_; // row chunk of memory for yuva planes 355 void* memory_argb_; // and for argb too. 356 void* pad7[2]; // padding for later use 357 }; 358 359 // Internal, version-checked, entry point 360 WEBP_EXTERN int WebPPictureInitInternal(WebPPicture*, int); 361 362 // Should always be called, to initialize the structure. Returns false in case 363 // of version mismatch. WebPPictureInit() must have succeeded before using the 364 // 'picture' object. 365 // Note that, by default, use_argb is false and colorspace is WEBP_YUV420. 366 static WEBP_INLINE int WebPPictureInit(WebPPicture* picture) { 367 return WebPPictureInitInternal(picture, WEBP_ENCODER_ABI_VERSION); 368 } 369 370 //------------------------------------------------------------------------------ 371 // WebPPicture utils 372 373 // Convenience allocation / deallocation based on picture->width/height: 374 // Allocate y/u/v buffers as per colorspace/width/height specification. 375 // Note! This function will free the previous buffer if needed. 376 // Returns false in case of memory error. 377 WEBP_EXTERN int WebPPictureAlloc(WebPPicture* picture); 378 379 // Release the memory allocated by WebPPictureAlloc() or WebPPictureImport*(). 380 // Note that this function does _not_ free the memory used by the 'picture' 381 // object itself. 382 // Besides memory (which is reclaimed) all other fields of 'picture' are 383 // preserved. 384 WEBP_EXTERN void WebPPictureFree(WebPPicture* picture); 385 386 // Copy the pixels of *src into *dst, using WebPPictureAlloc. Upon return, *dst 387 // will fully own the copied pixels (this is not a view). The 'dst' picture need 388 // not be initialized as its content is overwritten. 389 // Returns false in case of memory allocation error. 390 WEBP_EXTERN int WebPPictureCopy(const WebPPicture* src, WebPPicture* dst); 391 392 // Compute the single distortion for packed planes of samples. 393 // 'src' will be compared to 'ref', and the raw distortion stored into 394 // '*distortion'. The refined metric (log(MSE), log(1 - ssim),...' will be 395 // stored in '*result'. 396 // 'x_step' is the horizontal stride (in bytes) between samples. 397 // 'src/ref_stride' is the byte distance between rows. 398 // Returns false in case of error (bad parameter, memory allocation error, ...). 399 WEBP_EXTERN int WebPPlaneDistortion(const uint8_t* src, size_t src_stride, 400 const uint8_t* ref, size_t ref_stride, 401 int width, int height, 402 size_t x_step, 403 int type, // 0 = PSNR, 1 = SSIM, 2 = LSIM 404 float* distortion, float* result); 405 406 // Compute PSNR, SSIM or LSIM distortion metric between two pictures. Results 407 // are in dB, stored in result[] in the B/G/R/A/All order. The distortion is 408 // always performed using ARGB samples. Hence if the input is YUV(A), the 409 // picture will be internally converted to ARGB (just for the measurement). 410 // Warning: this function is rather CPU-intensive. 411 WEBP_EXTERN int WebPPictureDistortion( 412 const WebPPicture* src, const WebPPicture* ref, 413 int metric_type, // 0 = PSNR, 1 = SSIM, 2 = LSIM 414 float result[5]); 415 416 // self-crops a picture to the rectangle defined by top/left/width/height. 417 // Returns false in case of memory allocation error, or if the rectangle is 418 // outside of the source picture. 419 // The rectangle for the view is defined by the top-left corner pixel 420 // coordinates (left, top) as well as its width and height. This rectangle 421 // must be fully be comprised inside the 'src' source picture. If the source 422 // picture uses the YUV420 colorspace, the top and left coordinates will be 423 // snapped to even values. 424 WEBP_EXTERN int WebPPictureCrop(WebPPicture* picture, 425 int left, int top, int width, int height); 426 427 // Extracts a view from 'src' picture into 'dst'. The rectangle for the view 428 // is defined by the top-left corner pixel coordinates (left, top) as well 429 // as its width and height. This rectangle must be fully be comprised inside 430 // the 'src' source picture. If the source picture uses the YUV420 colorspace, 431 // the top and left coordinates will be snapped to even values. 432 // Picture 'src' must out-live 'dst' picture. Self-extraction of view is allowed 433 // ('src' equal to 'dst') as a mean of fast-cropping (but note that doing so, 434 // the original dimension will be lost). Picture 'dst' need not be initialized 435 // with WebPPictureInit() if it is different from 'src', since its content will 436 // be overwritten. 437 // Returns false in case of memory allocation error or invalid parameters. 438 WEBP_EXTERN int WebPPictureView(const WebPPicture* src, 439 int left, int top, int width, int height, 440 WebPPicture* dst); 441 442 // Returns true if the 'picture' is actually a view and therefore does 443 // not own the memory for pixels. 444 WEBP_EXTERN int WebPPictureIsView(const WebPPicture* picture); 445 446 // Rescale a picture to new dimension width x height. 447 // If either 'width' or 'height' (but not both) is 0 the corresponding 448 // dimension will be calculated preserving the aspect ratio. 449 // No gamma correction is applied. 450 // Returns false in case of error (invalid parameter or insufficient memory). 451 WEBP_EXTERN int WebPPictureRescale(WebPPicture* pic, int width, int height); 452 453 // Colorspace conversion function to import RGB samples. 454 // Previous buffer will be free'd, if any. 455 // *rgb buffer should have a size of at least height * rgb_stride. 456 // Returns false in case of memory error. 457 WEBP_EXTERN int WebPPictureImportRGB( 458 WebPPicture* picture, const uint8_t* rgb, int rgb_stride); 459 // Same, but for RGBA buffer. 460 WEBP_EXTERN int WebPPictureImportRGBA( 461 WebPPicture* picture, const uint8_t* rgba, int rgba_stride); 462 // Same, but for RGBA buffer. Imports the RGB direct from the 32-bit format 463 // input buffer ignoring the alpha channel. Avoids needing to copy the data 464 // to a temporary 24-bit RGB buffer to import the RGB only. 465 WEBP_EXTERN int WebPPictureImportRGBX( 466 WebPPicture* picture, const uint8_t* rgbx, int rgbx_stride); 467 468 // Variants of the above, but taking BGR(A|X) input. 469 WEBP_EXTERN int WebPPictureImportBGR( 470 WebPPicture* picture, const uint8_t* bgr, int bgr_stride); 471 WEBP_EXTERN int WebPPictureImportBGRA( 472 WebPPicture* picture, const uint8_t* bgra, int bgra_stride); 473 WEBP_EXTERN int WebPPictureImportBGRX( 474 WebPPicture* picture, const uint8_t* bgrx, int bgrx_stride); 475 476 // Converts picture->argb data to the YUV420A format. The 'colorspace' 477 // parameter is deprecated and should be equal to WEBP_YUV420. 478 // Upon return, picture->use_argb is set to false. The presence of real 479 // non-opaque transparent values is detected, and 'colorspace' will be 480 // adjusted accordingly. Note that this method is lossy. 481 // Returns false in case of error. 482 WEBP_EXTERN int WebPPictureARGBToYUVA(WebPPicture* picture, 483 WebPEncCSP /*colorspace = WEBP_YUV420*/); 484 485 // Same as WebPPictureARGBToYUVA(), but the conversion is done using 486 // pseudo-random dithering with a strength 'dithering' between 487 // 0.0 (no dithering) and 1.0 (maximum dithering). This is useful 488 // for photographic picture. 489 WEBP_EXTERN int WebPPictureARGBToYUVADithered( 490 WebPPicture* picture, WebPEncCSP colorspace, float dithering); 491 492 // Performs 'sharp' RGBA->YUVA420 downsampling and colorspace conversion. 493 // Downsampling is handled with extra care in case of color clipping. This 494 // method is roughly 2x slower than WebPPictureARGBToYUVA() but produces better 495 // and sharper YUV representation. 496 // Returns false in case of error. 497 WEBP_EXTERN int WebPPictureSharpARGBToYUVA(WebPPicture* picture); 498 // kept for backward compatibility: 499 WEBP_EXTERN int WebPPictureSmartARGBToYUVA(WebPPicture* picture); 500 501 // Converts picture->yuv to picture->argb and sets picture->use_argb to true. 502 // The input format must be YUV_420 or YUV_420A. The conversion from YUV420 to 503 // ARGB incurs a small loss too. 504 // Note that the use of this colorspace is discouraged if one has access to the 505 // raw ARGB samples, since using YUV420 is comparatively lossy. 506 // Returns false in case of error. 507 WEBP_EXTERN int WebPPictureYUVAToARGB(WebPPicture* picture); 508 509 // Helper function: given a width x height plane of RGBA or YUV(A) samples 510 // clean-up or smoothen the YUV or RGB samples under fully transparent area, 511 // to help compressibility (no guarantee, though). 512 WEBP_EXTERN void WebPCleanupTransparentArea(WebPPicture* picture); 513 514 // Scan the picture 'picture' for the presence of non fully opaque alpha values. 515 // Returns true in such case. Otherwise returns false (indicating that the 516 // alpha plane can be ignored altogether e.g.). 517 WEBP_EXTERN int WebPPictureHasTransparency(const WebPPicture* picture); 518 519 // Remove the transparency information (if present) by blending the color with 520 // the background color 'background_rgb' (specified as 24bit RGB triplet). 521 // After this call, all alpha values are reset to 0xff. 522 WEBP_EXTERN void WebPBlendAlpha(WebPPicture* pic, uint32_t background_rgb); 523 524 //------------------------------------------------------------------------------ 525 // Main call 526 527 // Main encoding call, after config and picture have been initialized. 528 // 'picture' must be less than 16384x16384 in dimension (cf WEBP_MAX_DIMENSION), 529 // and the 'config' object must be a valid one. 530 // Returns false in case of error, true otherwise. 531 // In case of error, picture->error_code is updated accordingly. 532 // 'picture' can hold the source samples in both YUV(A) or ARGB input, depending 533 // on the value of 'picture->use_argb'. It is highly recommended to use 534 // the former for lossy encoding, and the latter for lossless encoding 535 // (when config.lossless is true). Automatic conversion from one format to 536 // another is provided but they both incur some loss. 537 WEBP_EXTERN int WebPEncode(const WebPConfig* config, WebPPicture* picture); 538 539 //------------------------------------------------------------------------------ 540 541 #ifdef __cplusplus 542 } // extern "C" 543 #endif 544 545 #endif /* WEBP_WEBP_ENCODE_H_ */ 546
