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