| // Copyright 2011 Google Inc. All Rights Reserved. |
| // |
| // Use of this source code is governed by a BSD-style license |
| // that can be found in the COPYING file in the root of the source |
| // tree. An additional intellectual property rights grant can be found |
| // in the file PATENTS. All contributing project authors may |
| // be found in the AUTHORS file in the root of the source tree. |
| // ----------------------------------------------------------------------------- |
| // |
| // WebP encoder: main interface |
| // |
| // Author: Skal (pascal.massimino@gmail.com) |
| |
| #ifndef WEBP_WEBP_ENCODE_H_ |
| #define WEBP_WEBP_ENCODE_H_ |
| |
| #include "./types.h" |
| |
| #ifdef __cplusplus |
| extern "C" { |
| #endif |
| |
| #define WEBP_ENCODER_ABI_VERSION 0x0210 // MAJOR(8b) + MINOR(8b) |
| |
| // Note: forward declaring enumerations is not allowed in (strict) C and C++, |
| // the types are left here for reference. |
| // typedef enum WebPImageHint WebPImageHint; |
| // typedef enum WebPEncCSP WebPEncCSP; |
| // typedef enum WebPPreset WebPPreset; |
| // typedef enum WebPEncodingError WebPEncodingError; |
| typedef struct WebPConfig WebPConfig; |
| typedef struct WebPPicture WebPPicture; // main structure for I/O |
| typedef struct WebPAuxStats WebPAuxStats; |
| typedef struct WebPMemoryWriter WebPMemoryWriter; |
| |
| // Return the encoder's version number, packed in hexadecimal using 8bits for |
| // each of major/minor/revision. E.g: v2.5.7 is 0x020507. |
| WEBP_EXTERN int WebPGetEncoderVersion(void); |
| |
| //------------------------------------------------------------------------------ |
| // One-stop-shop call! No questions asked: |
| |
| // Returns the size of the compressed data (pointed to by *output), or 0 if |
| // an error occurred. The compressed data must be released by the caller |
| // using the call 'WebPFree(*output)'. |
| // These functions compress using the lossy format, and the quality_factor |
| // can go from 0 (smaller output, lower quality) to 100 (best quality, |
| // larger output). |
| WEBP_EXTERN size_t WebPEncodeRGB(const uint8_t* rgb, |
| int width, int height, int stride, |
| float quality_factor, uint8_t** output); |
| WEBP_EXTERN size_t WebPEncodeBGR(const uint8_t* bgr, |
| int width, int height, int stride, |
| float quality_factor, uint8_t** output); |
| WEBP_EXTERN size_t WebPEncodeRGBA(const uint8_t* rgba, |
| int width, int height, int stride, |
| float quality_factor, uint8_t** output); |
| WEBP_EXTERN size_t WebPEncodeBGRA(const uint8_t* bgra, |
| int width, int height, int stride, |
| float quality_factor, uint8_t** output); |
| |
| // These functions are the equivalent of the above, but compressing in a |
| // lossless manner. Files are usually larger than lossy format, but will |
| // not suffer any compression loss. |
| // Note these functions, like the lossy versions, use the library's default |
| // settings. For lossless this means 'exact' is disabled. RGB values in |
| // transparent areas will be modified to improve compression. To avoid this, |
| // use WebPEncode() and set WebPConfig::exact to 1. |
| WEBP_EXTERN size_t WebPEncodeLosslessRGB(const uint8_t* rgb, |
| int width, int height, int stride, |
| uint8_t** output); |
| WEBP_EXTERN size_t WebPEncodeLosslessBGR(const uint8_t* bgr, |
| int width, int height, int stride, |
| uint8_t** output); |
| WEBP_EXTERN size_t WebPEncodeLosslessRGBA(const uint8_t* rgba, |
| int width, int height, int stride, |
| uint8_t** output); |
| WEBP_EXTERN size_t WebPEncodeLosslessBGRA(const uint8_t* bgra, |
| int width, int height, int stride, |
| uint8_t** output); |
| |
| //------------------------------------------------------------------------------ |
| // Coding parameters |
| |
| // Image characteristics hint for the underlying encoder. |
| typedef enum WebPImageHint { |
| WEBP_HINT_DEFAULT = 0, // default preset. |
| WEBP_HINT_PICTURE, // digital picture, like portrait, inner shot |
| WEBP_HINT_PHOTO, // outdoor photograph, with natural lighting |
| WEBP_HINT_GRAPH, // Discrete tone image (graph, map-tile etc). |
| WEBP_HINT_LAST |
| } WebPImageHint; |
| |
| // Compression parameters. |
| struct WebPConfig { |
| int lossless; // Lossless encoding (0=lossy(default), 1=lossless). |
| float quality; // between 0 and 100. For lossy, 0 gives the smallest |
| // size and 100 the largest. For lossless, this |
| // parameter is the amount of effort put into the |
| // compression: 0 is the fastest but gives larger |
| // files compared to the slowest, but best, 100. |
| int method; // quality/speed trade-off (0=fast, 6=slower-better) |
| |
| WebPImageHint image_hint; // Hint for image type (lossless only for now). |
| |
| int target_size; // if non-zero, set the desired target size in bytes. |
| // Takes precedence over the 'compression' parameter. |
| float target_PSNR; // if non-zero, specifies the minimal distortion to |
| // try to achieve. Takes precedence over target_size. |
| int segments; // maximum number of segments to use, in [1..4] |
| int sns_strength; // Spatial Noise Shaping. 0=off, 100=maximum. |
| int filter_strength; // range: [0 = off .. 100 = strongest] |
| int filter_sharpness; // range: [0 = off .. 7 = least sharp] |
| int filter_type; // filtering type: 0 = simple, 1 = strong (only used |
| // if filter_strength > 0 or autofilter > 0) |
| int autofilter; // Auto adjust filter's strength [0 = off, 1 = on] |
| int alpha_compression; // Algorithm for encoding the alpha plane (0 = none, |
| // 1 = compressed with WebP lossless). Default is 1. |
| int alpha_filtering; // Predictive filtering method for alpha plane. |
| // 0: none, 1: fast, 2: best. Default if 1. |
| int alpha_quality; // Between 0 (smallest size) and 100 (lossless). |
| // Default is 100. |
| int pass; // number of entropy-analysis passes (in [1..10]). |
| |
| int show_compressed; // if true, export the compressed picture back. |
| // In-loop filtering is not applied. |
| int preprocessing; // preprocessing filter: |
| // 0=none, 1=segment-smooth, 2=pseudo-random dithering |
| int partitions; // log2(number of token partitions) in [0..3]. Default |
| // is set to 0 for easier progressive decoding. |
| int partition_limit; // quality degradation allowed to fit the 512k limit |
| // on prediction modes coding (0: no degradation, |
| // 100: maximum possible degradation). |
| int emulate_jpeg_size; // If true, compression parameters will be remapped |
| // to better match the expected output size from |
| // JPEG compression. Generally, the output size will |
| // be similar but the degradation will be lower. |
| int thread_level; // If non-zero, try and use multi-threaded encoding. |
| int low_memory; // If set, reduce memory usage (but increase CPU use). |
| |
| int near_lossless; // Near lossless encoding [0 = max loss .. 100 = off |
| // (default)]. |
| int exact; // if non-zero, preserve the exact RGB values under |
| // transparent area. Otherwise, discard this invisible |
| // RGB information for better compression. The default |
| // value is 0. |
| |
| int use_delta_palette; // reserved for future lossless feature |
| int use_sharp_yuv; // if needed, use sharp (and slow) RGB->YUV conversion |
| |
| int qmin; // minimum permissible quality factor |
| int qmax; // maximum permissible quality factor |
| }; |
| |
| // Enumerate some predefined settings for WebPConfig, depending on the type |
| // of source picture. These presets are used when calling WebPConfigPreset(). |
| typedef enum WebPPreset { |
| WEBP_PRESET_DEFAULT = 0, // default preset. |
| WEBP_PRESET_PICTURE, // digital picture, like portrait, inner shot |
| WEBP_PRESET_PHOTO, // outdoor photograph, with natural lighting |
| WEBP_PRESET_DRAWING, // hand or line drawing, with high-contrast details |
| WEBP_PRESET_ICON, // small-sized colorful images |
| WEBP_PRESET_TEXT // text-like |
| } WebPPreset; |
| |
| // Internal, version-checked, entry point |
| WEBP_EXTERN int WebPConfigInitInternal(WebPConfig*, WebPPreset, float, int); |
| |
| // Should always be called, to initialize a fresh WebPConfig structure before |
| // modification. Returns false in case of version mismatch. WebPConfigInit() |
| // must have succeeded before using the 'config' object. |
| // Note that the default values are lossless=0 and quality=75. |
| static WEBP_INLINE int WebPConfigInit(WebPConfig* config) { |
| return WebPConfigInitInternal(config, WEBP_PRESET_DEFAULT, 75.f, |
| WEBP_ENCODER_ABI_VERSION); |
| } |
| |
| // This function will initialize the configuration according to a predefined |
| // set of parameters (referred to by 'preset') and a given quality factor. |
| // This function can be called as a replacement to WebPConfigInit(). Will |
| // return false in case of error. |
| static WEBP_INLINE int WebPConfigPreset(WebPConfig* config, |
| WebPPreset preset, float quality) { |
| return WebPConfigInitInternal(config, preset, quality, |
| WEBP_ENCODER_ABI_VERSION); |
| } |
| |
| // Activate the lossless compression mode with the desired efficiency level |
| // between 0 (fastest, lowest compression) and 9 (slower, best compression). |
| // A good default level is '6', providing a fair tradeoff between compression |
| // speed and final compressed size. |
| // This function will overwrite several fields from config: 'method', 'quality' |
| // and 'lossless'. Returns false in case of parameter error. |
| WEBP_EXTERN int WebPConfigLosslessPreset(WebPConfig* config, int level); |
| |
| // Returns true if 'config' is non-NULL and all configuration parameters are |
| // within their valid ranges. |
| WEBP_EXTERN int WebPValidateConfig(const WebPConfig* config); |
| |
| //------------------------------------------------------------------------------ |
| // Input / Output |
| // Structure for storing auxiliary statistics. |
| |
| struct WebPAuxStats { |
| int coded_size; // final size |
| |
| float PSNR[5]; // peak-signal-to-noise ratio for Y/U/V/All/Alpha |
| int block_count[3]; // number of intra4/intra16/skipped macroblocks |
| int header_bytes[2]; // approximate number of bytes spent for header |
| // and mode-partition #0 |
| int residual_bytes[3][4]; // approximate number of bytes spent for |
| // DC/AC/uv coefficients for each (0..3) segments. |
| int segment_size[4]; // number of macroblocks in each segments |
| int segment_quant[4]; // quantizer values for each segments |
| int segment_level[4]; // filtering strength for each segments [0..63] |
| |
| int alpha_data_size; // size of the transparency data |
| int layer_data_size; // size of the enhancement layer data |
| |
| // lossless encoder statistics |
| uint32_t lossless_features; // bit0:predictor bit1:cross-color transform |
| // bit2:subtract-green bit3:color indexing |
| int histogram_bits; // number of precision bits of histogram |
| int transform_bits; // precision bits for transform |
| int cache_bits; // number of bits for color cache lookup |
| int palette_size; // number of color in palette, if used |
| int lossless_size; // final lossless size |
| int lossless_hdr_size; // lossless header (transform, huffman etc) size |
| int lossless_data_size; // lossless image data size |
| |
| uint32_t pad[2]; // padding for later use |
| }; |
| |
| // Signature for output function. Should return true if writing was successful. |
| // data/data_size is the segment of data to write, and 'picture' is for |
| // reference (and so one can make use of picture->custom_ptr). |
| typedef int (*WebPWriterFunction)(const uint8_t* data, size_t data_size, |
| const WebPPicture* picture); |
| |
| // WebPMemoryWrite: a special WebPWriterFunction that writes to memory using |
| // the following WebPMemoryWriter object (to be set as a custom_ptr). |
| struct WebPMemoryWriter { |
| uint8_t* mem; // final buffer (of size 'max_size', larger than 'size'). |
| size_t size; // final size |
| size_t max_size; // total capacity |
| uint32_t pad[1]; // padding for later use |
| }; |
| |
| // The following must be called first before any use. |
| WEBP_EXTERN void WebPMemoryWriterInit(WebPMemoryWriter* writer); |
| |
| // The following must be called to deallocate writer->mem memory. The 'writer' |
| // object itself is not deallocated. |
| WEBP_EXTERN void WebPMemoryWriterClear(WebPMemoryWriter* writer); |
| // The custom writer to be used with WebPMemoryWriter as custom_ptr. Upon |
| // completion, writer.mem and writer.size will hold the coded data. |
| // writer.mem must be freed by calling WebPMemoryWriterClear. |
| WEBP_EXTERN int WebPMemoryWrite(const uint8_t* data, size_t data_size, |
| const WebPPicture* picture); |
| |
| // Progress hook, called from time to time to report progress. It can return |
| // false to request an abort of the encoding process, or true otherwise if |
| // everything is OK. |
| typedef int (*WebPProgressHook)(int percent, const WebPPicture* picture); |
| |
| // Color spaces. |
| typedef enum WebPEncCSP { |
| // chroma sampling |
| WEBP_YUV420 = 0, // 4:2:0 |
| WEBP_YUV420A = 4, // alpha channel variant |
| WEBP_CSP_UV_MASK = 3, // bit-mask to get the UV sampling factors |
| WEBP_CSP_ALPHA_BIT = 4 // bit that is set if alpha is present |
| } WebPEncCSP; |
| |
| // Encoding error conditions. |
| typedef enum WebPEncodingError { |
| VP8_ENC_OK = 0, |
| VP8_ENC_ERROR_OUT_OF_MEMORY, // memory error allocating objects |
| VP8_ENC_ERROR_BITSTREAM_OUT_OF_MEMORY, // memory error while flushing bits |
| VP8_ENC_ERROR_NULL_PARAMETER, // a pointer parameter is NULL |
| VP8_ENC_ERROR_INVALID_CONFIGURATION, // configuration is invalid |
| VP8_ENC_ERROR_BAD_DIMENSION, // picture has invalid width/height |
| VP8_ENC_ERROR_PARTITION0_OVERFLOW, // partition is bigger than 512k |
| VP8_ENC_ERROR_PARTITION_OVERFLOW, // partition is bigger than 16M |
| VP8_ENC_ERROR_BAD_WRITE, // error while flushing bytes |
| VP8_ENC_ERROR_FILE_TOO_BIG, // file is bigger than 4G |
| VP8_ENC_ERROR_USER_ABORT, // abort request by user |
| VP8_ENC_ERROR_LAST // list terminator. always last. |
| } WebPEncodingError; |
| |
| // maximum width/height allowed (inclusive), in pixels |
| #define WEBP_MAX_DIMENSION 16383 |
| |
| // Main exchange structure (input samples, output bytes, statistics) |
| struct WebPPicture { |
| // INPUT |
| ////////////// |
| // Main flag for encoder selecting between ARGB or YUV input. |
| // It is recommended to use ARGB input (*argb, argb_stride) for lossless |
| // compression, and YUV input (*y, *u, *v, etc.) for lossy compression |
| // since these are the respective native colorspace for these formats. |
| int use_argb; |
| |
| // YUV input (mostly used for input to lossy compression) |
| WebPEncCSP colorspace; // colorspace: should be YUV420 for now (=Y'CbCr). |
| int width, height; // dimensions (less or equal to WEBP_MAX_DIMENSION) |
| uint8_t* y, *u, *v; // pointers to luma/chroma planes. |
| int y_stride, uv_stride; // luma/chroma strides. |
| uint8_t* a; // pointer to the alpha plane |
| int a_stride; // stride of the alpha plane |
| uint32_t pad1[2]; // padding for later use |
| |
| // ARGB input (mostly used for input to lossless compression) |
| uint32_t* argb; // Pointer to argb (32 bit) plane. |
| int argb_stride; // This is stride in pixels units, not bytes. |
| uint32_t pad2[3]; // padding for later use |
| |
| // OUTPUT |
| /////////////// |
| // Byte-emission hook, to store compressed bytes as they are ready. |
| WebPWriterFunction writer; // can be NULL |
| void* custom_ptr; // can be used by the writer. |
| |
| // map for extra information (only for lossy compression mode) |
| int extra_info_type; // 1: intra type, 2: segment, 3: quant |
| // 4: intra-16 prediction mode, |
| // 5: chroma prediction mode, |
| // 6: bit cost, 7: distortion |
| uint8_t* extra_info; // if not NULL, points to an array of size |
| // ((width + 15) / 16) * ((height + 15) / 16) that |
| // will be filled with a macroblock map, depending |
| // on extra_info_type. |
| |
| // STATS AND REPORTS |
| /////////////////////////// |
| // Pointer to side statistics (updated only if not NULL) |
| WebPAuxStats* stats; |
| |
| // Error code for the latest error encountered during encoding |
| WebPEncodingError error_code; |
| |
| // If not NULL, report progress during encoding. |
| WebPProgressHook progress_hook; |
| |
| void* user_data; // this field is free to be set to any value and |
| // used during callbacks (like progress-report e.g.). |
| |
| uint32_t pad3[3]; // padding for later use |
| |
| // Unused for now |
| uint8_t* pad4, *pad5; |
| uint32_t pad6[8]; // padding for later use |
| |
| // PRIVATE FIELDS |
| //////////////////// |
| void* memory_; // row chunk of memory for yuva planes |
| void* memory_argb_; // and for argb too. |
| void* pad7[2]; // padding for later use |
| }; |
| |
| // Internal, version-checked, entry point |
| WEBP_EXTERN int WebPPictureInitInternal(WebPPicture*, int); |
| |
| // Should always be called, to initialize the structure. Returns false in case |
| // of version mismatch. WebPPictureInit() must have succeeded before using the |
| // 'picture' object. |
| // Note that, by default, use_argb is false and colorspace is WEBP_YUV420. |
| static WEBP_INLINE int WebPPictureInit(WebPPicture* picture) { |
| return WebPPictureInitInternal(picture, WEBP_ENCODER_ABI_VERSION); |
| } |
| |
| //------------------------------------------------------------------------------ |
| // WebPPicture utils |
| |
| // Convenience allocation / deallocation based on picture->width/height: |
| // Allocate y/u/v buffers as per colorspace/width/height specification. |
| // Note! This function will free the previous buffer if needed. |
| // Returns false in case of memory error. |
| WEBP_EXTERN int WebPPictureAlloc(WebPPicture* picture); |
| |
| // Release the memory allocated by WebPPictureAlloc() or WebPPictureImport*(). |
| // Note that this function does _not_ free the memory used by the 'picture' |
| // object itself. |
| // Besides memory (which is reclaimed) all other fields of 'picture' are |
| // preserved. |
| WEBP_EXTERN void WebPPictureFree(WebPPicture* picture); |
| |
| // Copy the pixels of *src into *dst, using WebPPictureAlloc. Upon return, *dst |
| // will fully own the copied pixels (this is not a view). The 'dst' picture need |
| // not be initialized as its content is overwritten. |
| // Returns false in case of memory allocation error. |
| WEBP_EXTERN int WebPPictureCopy(const WebPPicture* src, WebPPicture* dst); |
| |
| // Compute the single distortion for packed planes of samples. |
| // 'src' will be compared to 'ref', and the raw distortion stored into |
| // '*distortion'. The refined metric (log(MSE), log(1 - ssim),...' will be |
| // stored in '*result'. |
| // 'x_step' is the horizontal stride (in bytes) between samples. |
| // 'src/ref_stride' is the byte distance between rows. |
| // Returns false in case of error (bad parameter, memory allocation error, ...). |
| WEBP_EXTERN int WebPPlaneDistortion(const uint8_t* src, size_t src_stride, |
| const uint8_t* ref, size_t ref_stride, |
| int width, int height, |
| size_t x_step, |
| int type, // 0 = PSNR, 1 = SSIM, 2 = LSIM |
| float* distortion, float* result); |
| |
| // Compute PSNR, SSIM or LSIM distortion metric between two pictures. Results |
| // are in dB, stored in result[] in the B/G/R/A/All order. The distortion is |
| // always performed using ARGB samples. Hence if the input is YUV(A), the |
| // picture will be internally converted to ARGB (just for the measurement). |
| // Warning: this function is rather CPU-intensive. |
| WEBP_EXTERN int WebPPictureDistortion( |
| const WebPPicture* src, const WebPPicture* ref, |
| int metric_type, // 0 = PSNR, 1 = SSIM, 2 = LSIM |
| float result[5]); |
| |
| // self-crops a picture to the rectangle defined by top/left/width/height. |
| // Returns false in case of memory allocation error, or if the rectangle is |
| // outside of the source picture. |
| // The rectangle for the view is defined by the top-left corner pixel |
| // coordinates (left, top) as well as its width and height. This rectangle |
| // must be fully be comprised inside the 'src' source picture. If the source |
| // picture uses the YUV420 colorspace, the top and left coordinates will be |
| // snapped to even values. |
| WEBP_EXTERN int WebPPictureCrop(WebPPicture* picture, |
| int left, int top, int width, int height); |
| |
| // Extracts a view from 'src' picture into 'dst'. The rectangle for the view |
| // is defined by the top-left corner pixel coordinates (left, top) as well |
| // as its width and height. This rectangle must be fully be comprised inside |
| // the 'src' source picture. If the source picture uses the YUV420 colorspace, |
| // the top and left coordinates will be snapped to even values. |
| // Picture 'src' must out-live 'dst' picture. Self-extraction of view is allowed |
| // ('src' equal to 'dst') as a mean of fast-cropping (but note that doing so, |
| // the original dimension will be lost). Picture 'dst' need not be initialized |
| // with WebPPictureInit() if it is different from 'src', since its content will |
| // be overwritten. |
| // Returns false in case of memory allocation error or invalid parameters. |
| WEBP_EXTERN int WebPPictureView(const WebPPicture* src, |
| int left, int top, int width, int height, |
| WebPPicture* dst); |
| |
| // Returns true if the 'picture' is actually a view and therefore does |
| // not own the memory for pixels. |
| WEBP_EXTERN int WebPPictureIsView(const WebPPicture* picture); |
| |
| // Rescale a picture to new dimension width x height. |
| // If either 'width' or 'height' (but not both) is 0 the corresponding |
| // dimension will be calculated preserving the aspect ratio. |
| // No gamma correction is applied. |
| // Returns false in case of error (invalid parameter or insufficient memory). |
| WEBP_EXTERN int WebPPictureRescale(WebPPicture* pic, int width, int height); |
| |
| // Colorspace conversion function to import RGB samples. |
| // Previous buffer will be free'd, if any. |
| // *rgb buffer should have a size of at least height * rgb_stride. |
| // Returns false in case of memory error. |
| WEBP_EXTERN int WebPPictureImportRGB( |
| WebPPicture* picture, const uint8_t* rgb, int rgb_stride); |
| // Same, but for RGBA buffer. |
| WEBP_EXTERN int WebPPictureImportRGBA( |
| WebPPicture* picture, const uint8_t* rgba, int rgba_stride); |
| // Same, but for RGBA buffer. Imports the RGB direct from the 32-bit format |
| // input buffer ignoring the alpha channel. Avoids needing to copy the data |
| // to a temporary 24-bit RGB buffer to import the RGB only. |
| WEBP_EXTERN int WebPPictureImportRGBX( |
| WebPPicture* picture, const uint8_t* rgbx, int rgbx_stride); |
| |
| // Variants of the above, but taking BGR(A|X) input. |
| WEBP_EXTERN int WebPPictureImportBGR( |
| WebPPicture* picture, const uint8_t* bgr, int bgr_stride); |
| WEBP_EXTERN int WebPPictureImportBGRA( |
| WebPPicture* picture, const uint8_t* bgra, int bgra_stride); |
| WEBP_EXTERN int WebPPictureImportBGRX( |
| WebPPicture* picture, const uint8_t* bgrx, int bgrx_stride); |
| |
| // Converts picture->argb data to the YUV420A format. The 'colorspace' |
| // parameter is deprecated and should be equal to WEBP_YUV420. |
| // Upon return, picture->use_argb is set to false. The presence of real |
| // non-opaque transparent values is detected, and 'colorspace' will be |
| // adjusted accordingly. Note that this method is lossy. |
| // Returns false in case of error. |
| WEBP_EXTERN int WebPPictureARGBToYUVA(WebPPicture* picture, |
| WebPEncCSP /*colorspace = WEBP_YUV420*/); |
| |
| // Same as WebPPictureARGBToYUVA(), but the conversion is done using |
| // pseudo-random dithering with a strength 'dithering' between |
| // 0.0 (no dithering) and 1.0 (maximum dithering). This is useful |
| // for photographic picture. |
| WEBP_EXTERN int WebPPictureARGBToYUVADithered( |
| WebPPicture* picture, WebPEncCSP colorspace, float dithering); |
| |
| // Performs 'sharp' RGBA->YUVA420 downsampling and colorspace conversion. |
| // Downsampling is handled with extra care in case of color clipping. This |
| // method is roughly 2x slower than WebPPictureARGBToYUVA() but produces better |
| // and sharper YUV representation. |
| // Returns false in case of error. |
| WEBP_EXTERN int WebPPictureSharpARGBToYUVA(WebPPicture* picture); |
| // kept for backward compatibility: |
| WEBP_EXTERN int WebPPictureSmartARGBToYUVA(WebPPicture* picture); |
| |
| // Converts picture->yuv to picture->argb and sets picture->use_argb to true. |
| // The input format must be YUV_420 or YUV_420A. The conversion from YUV420 to |
| // ARGB incurs a small loss too. |
| // Note that the use of this colorspace is discouraged if one has access to the |
| // raw ARGB samples, since using YUV420 is comparatively lossy. |
| // Returns false in case of error. |
| WEBP_EXTERN int WebPPictureYUVAToARGB(WebPPicture* picture); |
| |
| // Helper function: given a width x height plane of RGBA or YUV(A) samples |
| // clean-up or smoothen the YUV or RGB samples under fully transparent area, |
| // to help compressibility (no guarantee, though). |
| WEBP_EXTERN void WebPCleanupTransparentArea(WebPPicture* picture); |
| |
| // Scan the picture 'picture' for the presence of non fully opaque alpha values. |
| // Returns true in such case. Otherwise returns false (indicating that the |
| // alpha plane can be ignored altogether e.g.). |
| WEBP_EXTERN int WebPPictureHasTransparency(const WebPPicture* picture); |
| |
| // Remove the transparency information (if present) by blending the color with |
| // the background color 'background_rgb' (specified as 24bit RGB triplet). |
| // After this call, all alpha values are reset to 0xff. |
| WEBP_EXTERN void WebPBlendAlpha(WebPPicture* pic, uint32_t background_rgb); |
| |
| //------------------------------------------------------------------------------ |
| // Main call |
| |
| // Main encoding call, after config and picture have been initialized. |
| // 'picture' must be less than 16384x16384 in dimension (cf WEBP_MAX_DIMENSION), |
| // and the 'config' object must be a valid one. |
| // Returns false in case of error, true otherwise. |
| // In case of error, picture->error_code is updated accordingly. |
| // 'picture' can hold the source samples in both YUV(A) or ARGB input, depending |
| // on the value of 'picture->use_argb'. It is highly recommended to use |
| // the former for lossy encoding, and the latter for lossless encoding |
| // (when config.lossless is true). Automatic conversion from one format to |
| // another is provided but they both incur some loss. |
| WEBP_EXTERN int WebPEncode(const WebPConfig* config, WebPPicture* picture); |
| |
| //------------------------------------------------------------------------------ |
| |
| #ifdef __cplusplus |
| } // extern "C" |
| #endif |
| |
| #endif // WEBP_WEBP_ENCODE_H_ |
