third_party/libwebp/utils/filters.h

   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 // Spatial prediction using various filters
  11 //
  12 // Author: Urvang (urvang@google.com)
  13
  14 #ifndef WEBP_UTILS_FILTERS_H_
  15 #define WEBP_UTILS_FILTERS_H_
  16
  17 #include "../webp/types.h"
  18
  19 #if defined(__cplusplus) || defined(c_plusplus)
  20 extern "C" {
  21 #endif
  22
  23 // Filters.
  24 typedef enum {
  25   WEBP_FILTER_NONE = 0,
  26   WEBP_FILTER_HORIZONTAL,
  27   WEBP_FILTER_VERTICAL,
  28   WEBP_FILTER_GRADIENT,
  29   WEBP_FILTER_LAST = WEBP_FILTER_GRADIENT + 1,  // end marker
  30   WEBP_FILTER_BEST,
  31   WEBP_FILTER_FAST
  32 } WEBP_FILTER_TYPE;
  33
  34 typedef void (*WebPFilterFunc)(const uint8_t* in, int width, int height,
  35                                int stride, uint8_t* out);
  36 typedef void (*WebPUnfilterFunc)(int width, int height, int stride,
  37                                  uint8_t* data);
  38
  39 // Filter the given data using the given predictor.
  40 // 'in' corresponds to a 2-dimensional pixel array of size (stride * height)
  41 // in raster order.
  42 // 'stride' is number of bytes per scan line (with possible padding).
  43 // 'out' should be pre-allocated.
  44 extern const WebPFilterFunc WebPFilters[WEBP_FILTER_LAST];
  45
  46 // In-place reconstruct the original data from the given filtered data.
  47 extern const WebPUnfilterFunc WebPUnfilters[WEBP_FILTER_LAST];
  48
  49 // Fast estimate of a potentially good filter.
  50 extern WEBP_FILTER_TYPE EstimateBestFilter(const uint8_t* data,
  51                                            int width, int height, int stride);
  52
  53 #if defined(__cplusplus) || defined(c_plusplus)
  54 }    // extern "C"
  55 #endif
  56
  57 #endif  /* WEBP_UTILS_FILTERS_H_ */