Edit File: webpimg.h
/*===========================================================================* - Copyright 2010 Google Inc. - - This code is licensed under the same terms as WebM: - Software License Agreement: http://www.webmproject.org/license/software/ - Additional IP Rights Grant: http://www.webmproject.org/license/additional/ *===========================================================================*/ /* * Encoding/Decoding of WebP still image compression format. * * 1. WebPDecode: Takes an array of bytes (string) corresponding to the WebP * encoded image and generates output in the YUV format with * the color components U, V subsampled to 1/2 resolution along * each dimension. * * 2. YUV420toRGBA: Converts from YUV (with color subsampling) such as produced * by the WebPDecode routine into 32 bits per pixel RGBA data * array. This data array can be directly used by the Leptonica * Pix in-memory image format. * * 3. WebPEncode: Takes a Y, U, V data buffers (with color components U and V * subsampled to 1/2 resolution) and generates the WebP string * * 4. RGBAToYUV420: Generates Y, U, V data (with color subsampling) from 32 bits * per pixel RGBA data buffer. The resulting YUV data can be * directly fed into the WebPEncode routine. * * 5. AdjustColorspace: * * 6. AdjustColorspaceBack: */ #ifndef THIRD_PARTY_VP8_VP8IMG_H_ #define THIRD_PARTY_VP8_VP8IMG_H_ #ifdef __cplusplus extern "C" { #endif /* __cplusplus */ typedef unsigned char uint8; typedef unsigned int uint32; typedef enum WebPResultType { webp_success = 0, webp_failure = -1 } WebPResult; /* Takes an array of bytes (string) corresponding to the WebP * encoded image and generates output in the YUV format with * the color components U, V subsampled to 1/2 resolution along * each dimension. * Input: * 1. data: the WebP data stream (array of bytes) * 2. data_size: count of bytes in the WebP data stream * * Output: * 3. p_Y/p_U/p_V : pointer to the Y/U/V data buffer (this routine will * allocate memory for the buffer, fill the buffer with * appropriate data and transfer owner ship of the buffer * to caller. Caller is responsible for freeing the memory). * Note that the memory for Y, U, V buffers is alloacted * in one chunk, hence one should call free(*p_Y) only. * Do not try to free the U and V buffers. * * 6. p_width: this routine returns the width of the decoded image here * 7. p_height: this routine returns the width of the decoded image here * Return: success/failure */ WebPResult WebPDecode(const uint8* data, int data_size, uint8** p_Y, uint8** p_U, uint8** p_V, int* p_width, int* p_height); /* WebPEncode: Takes a Y, U, V data buffers (with color components U and V * subsampled to 1/2 resolution) and generates the WebP string. * Input: * 1, 2, 3. Y, U, V: The input YUV data buffers * 4, 5. y_width, y_height: The width and height of the image whose data * is in Y, U, V. This matches the Y plane. The U * and V planes typically have 1/2 width and * height. * 6. y_stride: The width (in bytes) of one row of Y data. This may not * match width if there is end of row padding (e.g., for 32 * bit row alignment). * 7. QP: the quantization parameter. This parameter controls the * compression vs quality tradeoff. Use smaller numbers for better * quality (compression will be lesser) and vice versa. 20 is a * good optimal value. * Output: * 8. p_out: the output array of bytes corresponding to the encoded WebP * image. This routine allocates memory for the buffer, fills it * with appropriate values and transfers ownership to caller. * Caller responsible for freeing of memory. * Return: success/failure */ WebPResult WebPEncode(const uint8* Y, const uint8* U, const uint8* V, int y_width, int y_height, int y_stride, int uv_width, int uv_height, int uv_stride, int QP, unsigned char** p_out, int* p_out_size_bytes, double* psnr); /* Converts from YUV (with color subsampling) such as produced by the WebPDecode * routine into 32 bits per pixel RGBA data array. This data array can be * directly used by the Leptonica Pix in-memory image format. * Input: * 1, 2, 3. Y, U, V: the input data buffers * 4. pixwpl: the desired words per line corresponding to the supplied * output pixdata. * 5. width, height: the dimensions of the image whose data resides in Y, * U, V. * Output: * 6. pixdata: the output data buffer. Caller should allocate * height * pixwpl bytes of memory before calling this routine. */ void YUV420toRGBA(uint8* Y, uint8* U, uint8* V, int words_per_line, int width, int height, uint32* pixdata); /* Generates Y, U, V data (with color subsampling) from 32 bits * per pixel RGBA data buffer. The resulting YUV data can be directly fed into * the WebPEncode routine. * Input: * 1. pix data input rgba data buffer * 2. words per line corresponding to pixdata * 3, 4. image width and height respectively * Output: * 5, 6, 7. Output YUV data buffers */ void RGBAToYUV420(uint32* pixdata, int words_per_line, int width, int height, uint8* Y, uint8* U, uint8* V); /* This function adjust from YUV420J (jpeg decoding) to YUV420 (webp input) * Hints: http://en.wikipedia.org/wiki/YCbCr */ void AdjustColorspace(uint8* Y, uint8* U, uint8* V, int width, int height); /* Inverse function: convert from YUV420 to YUV420J */ void AdjustColorspaceBack(uint8* Y, uint8* U, uint8* V, int width, int height); /* Checks WebP image header and outputs height and width information of * the image * * Input: * 1. data: the WebP data stream (array of bytes) * 2. data_size: count of bytes in the WebP data stream * * Outut: * width/height: width and height of the image * * Return: success/failure */ WebPResult WebPGetInfo(const uint8* data, int data_size, int *width, int *height); #ifdef __cplusplus } #endif /* __cplusplus */ #endif /* THIRD_PARTY_VP8_VP8IMG_H_ */
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