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@gmail.com)
13
14#ifndef WEBP_WEBP_ENCODE_H_
15#define WEBP_WEBP_ENCODE_H_
16
17#include "./types.h"
18
19#ifdef __cplusplus
20extern "C" {
21#endif
22
23#define WEBP_ENCODER_ABI_VERSION 0x020f // 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;
31typedef struct WebPConfig WebPConfig;
32typedef struct WebPPicture WebPPicture; // main structure for I/O
33typedef struct WebPAuxStats WebPAuxStats;
34typedef 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.
38WEBP_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).
49WEBP_EXTERN size_t WebPEncodeRGB(const uint8_t* rgb,
50 int width, int height, int stride,
51 float quality_factor, uint8_t** output);
52WEBP_EXTERN size_t WebPEncodeBGR(const uint8_t* bgr,
53 int width, int height, int stride,
54 float quality_factor, uint8_t** output);
55WEBP_EXTERN size_t WebPEncodeRGBA(const uint8_t* rgba,
56 int width, int height, int stride,
57 float quality_factor, uint8_t** output);
58WEBP_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// Note these functions, like the lossy versions, use the library's default
66// settings. For lossless this means 'exact' is disabled. RGB values in
67// transparent areas will be modified to improve compression. To avoid this,
68// use WebPEncode() and set WebPConfig::exact to 1.
69WEBP_EXTERN size_t WebPEncodeLosslessRGB(const uint8_t* rgb,
70 int width, int height, int stride,
71 uint8_t** output);
72WEBP_EXTERN size_t WebPEncodeLosslessBGR(const uint8_t* bgr,
73 int width, int height, int stride,
74 uint8_t** output);
75WEBP_EXTERN size_t WebPEncodeLosslessRGBA(const uint8_t* rgba,
76 int width, int height, int stride,
77 uint8_t** output);
78WEBP_EXTERN size_t WebPEncodeLosslessBGRA(const uint8_t* bgra,
79 int width, int height, int stride,
80 uint8_t** output);
81
82//------------------------------------------------------------------------------
83// Coding parameters
84
85// Image characteristics hint for the underlying encoder.
86typedef enum WebPImageHint {
87 WEBP_HINT_DEFAULT = 0, // default preset.
88 WEBP_HINT_PICTURE, // digital picture, like portrait, inner shot
89 WEBP_HINT_PHOTO, // outdoor photograph, with natural lighting
90 WEBP_HINT_GRAPH, // Discrete tone image (graph, map-tile etc).
91 WEBP_HINT_LAST
92} WebPImageHint;
93
94// Compression parameters.
95struct WebPConfig {
96 int lossless; // Lossless encoding (0=lossy(default), 1=lossless).
97 float quality; // between 0 and 100. For lossy, 0 gives the smallest
98 // size and 100 the largest. For lossless, this
99 // parameter is the amount of effort put into the
100 // compression: 0 is the fastest but gives larger
101 // files compared to the slowest, but best, 100.
102 int method; // quality/speed trade-off (0=fast, 6=slower-better)
103
104 WebPImageHint image_hint; // Hint for image type (lossless only for now).
105
106 int target_size; // if non-zero, set the desired target size in bytes.
107 // Takes precedence over the 'compression' parameter.
108 float target_PSNR; // if non-zero, specifies the minimal distortion to
109 // try to achieve. Takes precedence over target_size.
110 int segments; // maximum number of segments to use, in [1..4]
111 int sns_strength; // Spatial Noise Shaping. 0=off, 100=maximum.
112 int filter_strength; // range: [0 = off .. 100 = strongest]
113 int filter_sharpness; // range: [0 = off .. 7 = least sharp]
114 int filter_type; // filtering type: 0 = simple, 1 = strong (only used
115 // if filter_strength > 0 or autofilter > 0)
116 int autofilter; // Auto adjust filter's strength [0 = off, 1 = on]
117 int alpha_compression; // Algorithm for encoding the alpha plane (0 = none,
118 // 1 = compressed with WebP lossless). Default is 1.
119 int alpha_filtering; // Predictive filtering method for alpha plane.
120 // 0: none, 1: fast, 2: best. Default if 1.
121 int alpha_quality; // Between 0 (smallest size) and 100 (lossless).
122 // Default is 100.
123 int pass; // number of entropy-analysis passes (in [1..10]).
124
125 int show_compressed; // if true, export the compressed picture back.
126 // In-loop filtering is not applied.
127 int preprocessing; // preprocessing filter:
128 // 0=none, 1=segment-smooth, 2=pseudo-random dithering
129 int partitions; // log2(number of token partitions) in [0..3]. Default
130 // is set to 0 for easier progressive decoding.
131 int partition_limit; // quality degradation allowed to fit the 512k limit
132 // on prediction modes coding (0: no degradation,
133 // 100: maximum possible degradation).
134 int emulate_jpeg_size; // If true, compression parameters will be remapped
135 // to better match the expected output size from
136 // JPEG compression. Generally, the output size will
137 // be similar but the degradation will be lower.
138 int thread_level; // If non-zero, try and use multi-threaded encoding.
139 int low_memory; // If set, reduce memory usage (but increase CPU use).
140
141 int near_lossless; // Near lossless encoding [0 = max loss .. 100 = off
142 // (default)].
143 int exact; // if non-zero, preserve the exact RGB values under
144 // transparent area. Otherwise, discard this invisible
145 // RGB information for better compression. The default
146 // value is 0.
147
148 int use_delta_palette; // reserved for future lossless feature
149 int use_sharp_yuv; // if needed, use sharp (and slow) RGB->YUV conversion
150
151 uint32_t pad[2]; // padding for later use
152};
153
154// Enumerate some predefined settings for WebPConfig, depending on the type
155// of source picture. These presets are used when calling WebPConfigPreset().
156typedef enum WebPPreset {
157 WEBP_PRESET_DEFAULT = 0, // default preset.
158 WEBP_PRESET_PICTURE, // digital picture, like portrait, inner shot
159 WEBP_PRESET_PHOTO, // outdoor photograph, with natural lighting
160 WEBP_PRESET_DRAWING, // hand or line drawing, with high-contrast details
161 WEBP_PRESET_ICON, // small-sized colorful images
162 WEBP_PRESET_TEXT // text-like
163} WebPPreset;
164
165// Internal, version-checked, entry point
166WEBP_EXTERN int WebPConfigInitInternal(WebPConfig*, WebPPreset, float, int);
167
168// Should always be called, to initialize a fresh WebPConfig structure before
169// modification. Returns false in case of version mismatch. WebPConfigInit()
170// must have succeeded before using the 'config' object.
171// Note that the default values are lossless=0 and quality=75.
172static WEBP_INLINE int WebPConfigInit(WebPConfig* config) {
173 return WebPConfigInitInternal(config, WEBP_PRESET_DEFAULT, 75.f,
174 WEBP_ENCODER_ABI_VERSION);
175}
176
177// This function will initialize the configuration according to a predefined
178// set of parameters (referred to by 'preset') and a given quality factor.
179// This function can be called as a replacement to WebPConfigInit(). Will
180// return false in case of error.
181static WEBP_INLINE int WebPConfigPreset(WebPConfig* config,
182 WebPPreset preset, float quality) {
183 return WebPConfigInitInternal(config, preset, quality,
184 WEBP_ENCODER_ABI_VERSION);
185}
186
187// Activate the lossless compression mode with the desired efficiency level
188// between 0 (fastest, lowest compression) and 9 (slower, best compression).
189// A good default level is '6', providing a fair tradeoff between compression
190// speed and final compressed size.
191// This function will overwrite several fields from config: 'method', 'quality'
192// and 'lossless'. Returns false in case of parameter error.
193WEBP_EXTERN int WebPConfigLosslessPreset(WebPConfig* config, int level);
194
195// Returns true if 'config' is non-NULL and all configuration parameters are
196// within their valid ranges.
197WEBP_EXTERN int WebPValidateConfig(const WebPConfig* config);
198
199//------------------------------------------------------------------------------
200// Input / Output
201// Structure for storing auxiliary statistics.
202
203struct WebPAuxStats {
204 int coded_size; // final size
205
206 float PSNR[5]; // peak-signal-to-noise ratio for Y/U/V/All/Alpha
207 int block_count[3]; // number of intra4/intra16/skipped macroblocks
208 int header_bytes[2]; // approximate number of bytes spent for header
209 // and mode-partition #0
210 int residual_bytes[3][4]; // approximate number of bytes spent for
211 // DC/AC/uv coefficients for each (0..3) segments.
212 int segment_size[4]; // number of macroblocks in each segments
213 int segment_quant[4]; // quantizer values for each segments
214 int segment_level[4]; // filtering strength for each segments [0..63]
215
216 int alpha_data_size; // size of the transparency data
217 int layer_data_size; // size of the enhancement layer data
218
219 // lossless encoder statistics
220 uint32_t lossless_features; // bit0:predictor bit1:cross-color transform
221 // bit2:subtract-green bit3:color indexing
222 int histogram_bits; // number of precision bits of histogram
223 int transform_bits; // precision bits for transform
224 int cache_bits; // number of bits for color cache lookup
225 int palette_size; // number of color in palette, if used
226 int lossless_size; // final lossless size
227 int lossless_hdr_size; // lossless header (transform, huffman etc) size
228 int lossless_data_size; // lossless image data size
229
230 uint32_t pad[2]; // padding for later use
231};
232
233// Signature for output function. Should return true if writing was successful.
234// data/data_size is the segment of data to write, and 'picture' is for
235// reference (and so one can make use of picture->custom_ptr).
236typedef int (*WebPWriterFunction)(const uint8_t* data, size_t data_size,
237 const WebPPicture* picture);
238
239// WebPMemoryWrite: a special WebPWriterFunction that writes to memory using
240// the following WebPMemoryWriter object (to be set as a custom_ptr).
241struct WebPMemoryWriter {
242 uint8_t* mem; // final buffer (of size 'max_size', larger than 'size').
243 size_t size; // final size
244 size_t max_size; // total capacity
245 uint32_t pad[1]; // padding for later use
246};
247
248// The following must be called first before any use.
249WEBP_EXTERN void WebPMemoryWriterInit(WebPMemoryWriter* writer);
250
251// The following must be called to deallocate writer->mem memory. The 'writer'
252// object itself is not deallocated.
253WEBP_EXTERN void WebPMemoryWriterClear(WebPMemoryWriter* writer);
254// The custom writer to be used with WebPMemoryWriter as custom_ptr. Upon
255// completion, writer.mem and writer.size will hold the coded data.
256// writer.mem must be freed by calling WebPMemoryWriterClear.
257WEBP_EXTERN int WebPMemoryWrite(const uint8_t* data, size_t data_size,
258 const WebPPicture* picture);
259
260// Progress hook, called from time to time to report progress. It can return
261// false to request an abort of the encoding process, or true otherwise if
262// everything is OK.
263typedef int (*WebPProgressHook)(int percent, const WebPPicture* picture);
264
265// Color spaces.
266typedef enum WebPEncCSP {
267 // chroma sampling
268 WEBP_YUV420 = 0, // 4:2:0
269 WEBP_YUV420A = 4, // alpha channel variant
270 WEBP_CSP_UV_MASK = 3, // bit-mask to get the UV sampling factors
271 WEBP_CSP_ALPHA_BIT = 4 // bit that is set if alpha is present
272} WebPEncCSP;
273
274// Encoding error conditions.
275typedef enum WebPEncodingError {
276 VP8_ENC_OK = 0,
277 VP8_ENC_ERROR_OUT_OF_MEMORY, // memory error allocating objects
278 VP8_ENC_ERROR_BITSTREAM_OUT_OF_MEMORY, // memory error while flushing bits
279 VP8_ENC_ERROR_NULL_PARAMETER, // a pointer parameter is NULL
280 VP8_ENC_ERROR_INVALID_CONFIGURATION, // configuration is invalid
281 VP8_ENC_ERROR_BAD_DIMENSION, // picture has invalid width/height
282 VP8_ENC_ERROR_PARTITION0_OVERFLOW, // partition is bigger than 512k
283 VP8_ENC_ERROR_PARTITION_OVERFLOW, // partition is bigger than 16M
284 VP8_ENC_ERROR_BAD_WRITE, // error while flushing bytes
285 VP8_ENC_ERROR_FILE_TOO_BIG, // file is bigger than 4G
286 VP8_ENC_ERROR_USER_ABORT, // abort request by user
287 VP8_ENC_ERROR_LAST // list terminator. always last.
288} WebPEncodingError;
289
290// maximum width/height allowed (inclusive), in pixels
291#define WEBP_MAX_DIMENSION 16383
292
293// Main exchange structure (input samples, output bytes, statistics)
294struct WebPPicture {
295 // INPUT
296 //////////////
297 // Main flag for encoder selecting between ARGB or YUV input.
298 // It is recommended to use ARGB input (*argb, argb_stride) for lossless
299 // compression, and YUV input (*y, *u, *v, etc.) for lossy compression
300 // since these are the respective native colorspace for these formats.
301 int use_argb;
302
303 // YUV input (mostly used for input to lossy compression)
304 WebPEncCSP colorspace; // colorspace: should be YUV420 for now (=Y'CbCr).
305 int width, height; // dimensions (less or equal to WEBP_MAX_DIMENSION)
306 uint8_t* y, *u, *v; // pointers to luma/chroma planes.
307 int y_stride, uv_stride; // luma/chroma strides.
308 uint8_t* a; // pointer to the alpha plane
309 int a_stride; // stride of the alpha plane
310 uint32_t pad1[2]; // padding for later use
311
312 // ARGB input (mostly used for input to lossless compression)
313 uint32_t* argb; // Pointer to argb (32 bit) plane.
314 int argb_stride; // This is stride in pixels units, not bytes.
315 uint32_t pad2[3]; // padding for later use
316
317 // OUTPUT
318 ///////////////
319 // Byte-emission hook, to store compressed bytes as they are ready.
320 WebPWriterFunction writer; // can be NULL
321 void* custom_ptr; // can be used by the writer.
322
323 // map for extra information (only for lossy compression mode)
324 int extra_info_type; // 1: intra type, 2: segment, 3: quant
325 // 4: intra-16 prediction mode,
326 // 5: chroma prediction mode,
327 // 6: bit cost, 7: distortion
328 uint8_t* extra_info; // if not NULL, points to an array of size
329 // ((width + 15) / 16) * ((height + 15) / 16) that
330 // will be filled with a macroblock map, depending
331 // on extra_info_type.
332
333 // STATS AND REPORTS
334 ///////////////////////////
335 // Pointer to side statistics (updated only if not NULL)
336 WebPAuxStats* stats;
337
338 // Error code for the latest error encountered during encoding
339 WebPEncodingError error_code;
340
341 // If not NULL, report progress during encoding.
342 WebPProgressHook progress_hook;
343
344 void* user_data; // this field is free to be set to any value and
345 // used during callbacks (like progress-report e.g.).
346
347 uint32_t pad3[3]; // padding for later use
348
349 // Unused for now
350 uint8_t* pad4, *pad5;
351 uint32_t pad6[8]; // padding for later use
352
353 // PRIVATE FIELDS
354 ////////////////////
355 void* memory_; // row chunk of memory for yuva planes
356 void* memory_argb_; // and for argb too.
357 void* pad7[2]; // padding for later use
358};
359
360// Internal, version-checked, entry point
361WEBP_EXTERN int WebPPictureInitInternal(WebPPicture*, int);
362
363// Should always be called, to initialize the structure. Returns false in case
364// of version mismatch. WebPPictureInit() must have succeeded before using the
365// 'picture' object.
366// Note that, by default, use_argb is false and colorspace is WEBP_YUV420.
367static WEBP_INLINE int WebPPictureInit(WebPPicture* picture) {
368 return WebPPictureInitInternal(picture, WEBP_ENCODER_ABI_VERSION);
369}
370
371//------------------------------------------------------------------------------
372// WebPPicture utils
373
374// Convenience allocation / deallocation based on picture->width/height:
375// Allocate y/u/v buffers as per colorspace/width/height specification.
376// Note! This function will free the previous buffer if needed.
377// Returns false in case of memory error.
378WEBP_EXTERN int WebPPictureAlloc(WebPPicture* picture);
379
380// Release the memory allocated by WebPPictureAlloc() or WebPPictureImport*().
381// Note that this function does _not_ free the memory used by the 'picture'
382// object itself.
383// Besides memory (which is reclaimed) all other fields of 'picture' are
384// preserved.
385WEBP_EXTERN void WebPPictureFree(WebPPicture* picture);
386
387// Copy the pixels of *src into *dst, using WebPPictureAlloc. Upon return, *dst
388// will fully own the copied pixels (this is not a view). The 'dst' picture need
389// not be initialized as its content is overwritten.
390// Returns false in case of memory allocation error.
391WEBP_EXTERN int WebPPictureCopy(const WebPPicture* src, WebPPicture* dst);
392
393// Compute the single distortion for packed planes of samples.
394// 'src' will be compared to 'ref', and the raw distortion stored into
395// '*distortion'. The refined metric (log(MSE), log(1 - ssim),...' will be
396// stored in '*result'.
397// 'x_step' is the horizontal stride (in bytes) between samples.
398// 'src/ref_stride' is the byte distance between rows.
399// Returns false in case of error (bad parameter, memory allocation error, ...).
400WEBP_EXTERN int WebPPlaneDistortion(const uint8_t* src, size_t src_stride,
401 const uint8_t* ref, size_t ref_stride,
402 int width, int height,
403 size_t x_step,
404 int type, // 0 = PSNR, 1 = SSIM, 2 = LSIM
405 float* distortion, float* result);
406
407// Compute PSNR, SSIM or LSIM distortion metric between two pictures. Results
408// are in dB, stored in result[] in the B/G/R/A/All order. The distortion is
409// always performed using ARGB samples. Hence if the input is YUV(A), the
410// picture will be internally converted to ARGB (just for the measurement).
411// Warning: this function is rather CPU-intensive.
412WEBP_EXTERN int WebPPictureDistortion(
413 const WebPPicture* src, const WebPPicture* ref,
414 int metric_type, // 0 = PSNR, 1 = SSIM, 2 = LSIM
415 float result[5]);
416
417// self-crops a picture to the rectangle defined by top/left/width/height.
418// Returns false in case of memory allocation error, or if the rectangle is
419// outside of the source picture.
420// The rectangle for the view is defined by the top-left corner pixel
421// coordinates (left, top) as well as its width and height. This rectangle
422// must be fully be comprised inside the 'src' source picture. If the source
423// picture uses the YUV420 colorspace, the top and left coordinates will be
424// snapped to even values.
425WEBP_EXTERN int WebPPictureCrop(WebPPicture* picture,
426 int left, int top, int width, int height);
427
428// Extracts a view from 'src' picture into 'dst'. The rectangle for the view
429// is defined by the top-left corner pixel coordinates (left, top) as well
430// as its width and height. This rectangle must be fully be comprised inside
431// the 'src' source picture. If the source picture uses the YUV420 colorspace,
432// the top and left coordinates will be snapped to even values.
433// Picture 'src' must out-live 'dst' picture. Self-extraction of view is allowed
434// ('src' equal to 'dst') as a mean of fast-cropping (but note that doing so,
435// the original dimension will be lost). Picture 'dst' need not be initialized
436// with WebPPictureInit() if it is different from 'src', since its content will
437// be overwritten.
438// Returns false in case of memory allocation error or invalid parameters.
439WEBP_EXTERN int WebPPictureView(const WebPPicture* src,
440 int left, int top, int width, int height,
441 WebPPicture* dst);
442
443// Returns true if the 'picture' is actually a view and therefore does
444// not own the memory for pixels.
445WEBP_EXTERN int WebPPictureIsView(const WebPPicture* picture);
446
447// Rescale a picture to new dimension width x height.
448// If either 'width' or 'height' (but not both) is 0 the corresponding
449// dimension will be calculated preserving the aspect ratio.
450// No gamma correction is applied.
451// Returns false in case of error (invalid parameter or insufficient memory).
452WEBP_EXTERN int WebPPictureRescale(WebPPicture* pic, int width, int height);
453
454// Colorspace conversion function to import RGB samples.
455// Previous buffer will be free'd, if any.
456// *rgb buffer should have a size of at least height * rgb_stride.
457// Returns false in case of memory error.
458WEBP_EXTERN int WebPPictureImportRGB(
459 WebPPicture* picture, const uint8_t* rgb, int rgb_stride);
460// Same, but for RGBA buffer.
461WEBP_EXTERN int WebPPictureImportRGBA(
462 WebPPicture* picture, const uint8_t* rgba, int rgba_stride);
463// Same, but for RGBA buffer. Imports the RGB direct from the 32-bit format
464// input buffer ignoring the alpha channel. Avoids needing to copy the data
465// to a temporary 24-bit RGB buffer to import the RGB only.
466WEBP_EXTERN int WebPPictureImportRGBX(
467 WebPPicture* picture, const uint8_t* rgbx, int rgbx_stride);
468
469// Variants of the above, but taking BGR(A|X) input.
470WEBP_EXTERN int WebPPictureImportBGR(
471 WebPPicture* picture, const uint8_t* bgr, int bgr_stride);
472WEBP_EXTERN int WebPPictureImportBGRA(
473 WebPPicture* picture, const uint8_t* bgra, int bgra_stride);
474WEBP_EXTERN int WebPPictureImportBGRX(
475 WebPPicture* picture, const uint8_t* bgrx, int bgrx_stride);
476
477// Converts picture->argb data to the YUV420A format. The 'colorspace'
478// parameter is deprecated and should be equal to WEBP_YUV420.
479// Upon return, picture->use_argb is set to false. The presence of real
480// non-opaque transparent values is detected, and 'colorspace' will be
481// adjusted accordingly. Note that this method is lossy.
482// Returns false in case of error.
483WEBP_EXTERN int WebPPictureARGBToYUVA(WebPPicture* picture,
484 WebPEncCSP /*colorspace = WEBP_YUV420*/);
485
486// Same as WebPPictureARGBToYUVA(), but the conversion is done using
487// pseudo-random dithering with a strength 'dithering' between
488// 0.0 (no dithering) and 1.0 (maximum dithering). This is useful
489// for photographic picture.
490WEBP_EXTERN int WebPPictureARGBToYUVADithered(
491 WebPPicture* picture, WebPEncCSP colorspace, float dithering);
492
493// Performs 'sharp' RGBA->YUVA420 downsampling and colorspace conversion.
494// Downsampling is handled with extra care in case of color clipping. This
495// method is roughly 2x slower than WebPPictureARGBToYUVA() but produces better
496// and sharper YUV representation.
497// Returns false in case of error.
498WEBP_EXTERN int WebPPictureSharpARGBToYUVA(WebPPicture* picture);
499// kept for backward compatibility:
500WEBP_EXTERN int WebPPictureSmartARGBToYUVA(WebPPicture* picture);
501
502// Converts picture->yuv to picture->argb and sets picture->use_argb to true.
503// The input format must be YUV_420 or YUV_420A. The conversion from YUV420 to
504// ARGB incurs a small loss too.
505// Note that the use of this colorspace is discouraged if one has access to the
506// raw ARGB samples, since using YUV420 is comparatively lossy.
507// Returns false in case of error.
508WEBP_EXTERN int WebPPictureYUVAToARGB(WebPPicture* picture);
509
510// Helper function: given a width x height plane of RGBA or YUV(A) samples
511// clean-up or smoothen the YUV or RGB samples under fully transparent area,
512// to help compressibility (no guarantee, though).
513WEBP_EXTERN void WebPCleanupTransparentArea(WebPPicture* picture);
514
515// Scan the picture 'picture' for the presence of non fully opaque alpha values.
516// Returns true in such case. Otherwise returns false (indicating that the
517// alpha plane can be ignored altogether e.g.).
518WEBP_EXTERN int WebPPictureHasTransparency(const WebPPicture* picture);
519
520// Remove the transparency information (if present) by blending the color with
521// the background color 'background_rgb' (specified as 24bit RGB triplet).
522// After this call, all alpha values are reset to 0xff.
523WEBP_EXTERN void WebPBlendAlpha(WebPPicture* pic, uint32_t background_rgb);
524
525//------------------------------------------------------------------------------
526// Main call
527
528// Main encoding call, after config and picture have been initialized.
529// 'picture' must be less than 16384x16384 in dimension (cf WEBP_MAX_DIMENSION),
530// and the 'config' object must be a valid one.
531// Returns false in case of error, true otherwise.
532// In case of error, picture->error_code is updated accordingly.
533// 'picture' can hold the source samples in both YUV(A) or ARGB input, depending
534// on the value of 'picture->use_argb'. It is highly recommended to use
535// the former for lossy encoding, and the latter for lossless encoding
536// (when config.lossless is true). Automatic conversion from one format to
537// another is provided but they both incur some loss.
538WEBP_EXTERN int WebPEncode(const WebPConfig* config, WebPPicture* picture);
539
540//------------------------------------------------------------------------------
541
542#ifdef __cplusplus
543} // extern "C"
544#endif
545
546#endif // WEBP_WEBP_ENCODE_H_
547