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#ifdef __cplusplus
20extern "C" {
21#endif
22
23// Filters.
24typedef 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
34typedef void (*WebPFilterFunc)(const uint8_t* in, int width, int height,
35                               int stride, uint8_t* out);
36typedef void (*WebPUnfilterFunc)(int width, int height, int stride,
37                                 int row, int num_rows, 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.
44extern const WebPFilterFunc WebPFilters[WEBP_FILTER_LAST];
45
46// In-place reconstruct the original data from the given filtered data.
47// The reconstruction will be done for 'num_rows' rows starting from 'row'
48// (assuming rows upto 'row - 1' are already reconstructed).
49extern const WebPUnfilterFunc WebPUnfilters[WEBP_FILTER_LAST];
50
51// Fast estimate of a potentially good filter.
52WEBP_FILTER_TYPE EstimateBestFilter(const uint8_t* data,
53                                    int width, int height, int stride);
54
55#ifdef __cplusplus
56}    // extern "C"
57#endif
58
59#endif  /* WEBP_UTILS_FILTERS_H_ */
60