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intfeaturespace.h
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1 // Copyright 2010 Google Inc. All Rights Reserved.
2 // Author: rays@google.com (Ray Smith)
4 // File: intfeaturespace.h
5 // Description: Indexed feature space based on INT_FEATURE_STRUCT.
6 // Created: Wed Mar 24 10:55:30 PDT 2010
7 //
8 // Licensed under the Apache License, Version 2.0 (the "License");
9 // you may not use this file except in compliance with the License.
10 // You may obtain a copy of the License at
11 // http://www.apache.org/licenses/LICENSE-2.0
12 // Unless required by applicable law or agreed to in writing, software
13 // distributed under the License is distributed on an "AS IS" BASIS,
14 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 // See the License for the specific language governing permissions and
16 // limitations under the License.
17 //
19
20 #ifndef TESSERACT_CLASSIFY_INTFEATURESPACE_H__
21 #define TESSERACT_CLASSIFY_INTFEATURESPACE_H__
22
23 #include "genericvector.h"
24 #include "intproto.h"
25
26 // Extent of x,y,theta in the input feature space. [0,255].
27 const int kIntFeatureExtent = 256;
28 // Extent of x,y,theta dimensions in the quantized feature space.
29 const int kBoostXYBuckets = 16;
30 const int kBoostDirBuckets = 16;
31
32 namespace tesseract {
33
34 class IndexMap;
35
36 // Down-sampling quantization of the INT_FEATURE_STRUCT feature space and
37 // conversion to a single scalar index value, used as a binary feature space.
38 class IntFeatureSpace {
39 public:
40 IntFeatureSpace();
41 // Default copy constructors and assignment OK!
42
43 // Setup the feature space with the given dimensions.
44 void Init(uinT8 xbuckets, uinT8 ybuckets, uinT8 thetabuckets);
45
46 // Serializes the feature space definition to the given file.
47 // Returns false on error.
48 bool Serialize(FILE* fp) const;
49
50 // DeSerializes the feature space definition from the given file.
51 // If swap is true, the data is big/little-endian swapped.
52 // Returns false on error.
53 bool DeSerialize(bool swap, FILE* fp);
54
55 // Returns the total size of the feature space.
56 int Size() const {
57 return static_cast<int>(x_buckets_) * y_buckets_ * theta_buckets_;
58 }
59 // Returns an INT_FEATURE_STRUCT corresponding to the given index.
60 // This is the inverse of the Index member.
61 INT_FEATURE_STRUCT PositionFromIndex(int index) const;
62
63 // Returns a 1-dimensional index corresponding to the given feature value.
64 // Range is [0, Size()-1]. Inverse of PositionFromIndex member.
65 int Index(const INT_FEATURE_STRUCT& f) const {
66 return (XBucket(f.X) * y_buckets_ + YBucket(f.Y)) * theta_buckets_ +
67 ThetaBucket(f.Theta);
68 }
69 // Bulk calls to Index. Maps the given array of features to a vector of
70 // inT32 indices in the same order as the input.
71 void IndexFeatures(const INT_FEATURE_STRUCT* features, int num_features,
72 GenericVector<int>* mapped_features) const;
73 // Bulk calls to Index. Maps the given array of features to a vector of
74 // sorted inT32 indices.
75 void IndexAndSortFeatures(const INT_FEATURE_STRUCT* features,
76 int num_features,
77 GenericVector<int>* sorted_features) const;
78 // Returns a feature space index for the given x,y position in a display
79 // window, or -1 if the feature is a miss.
80 int XYToFeatureIndex(int x, int y) const;
81
82 protected:
83 // Converters to generate indices for individual feature dimensions.
84 int XBucket(int x) const {
85 int bucket = x * x_buckets_ / kIntFeatureExtent;
86 return ClipToRange(bucket, 0, static_cast<int>(x_buckets_) - 1);
87 }
88 int YBucket(int y) const {
89 int bucket = y * y_buckets_ / kIntFeatureExtent;
90 return ClipToRange(bucket, 0, static_cast<int>(y_buckets_) - 1);
91 }
92 // Use DivRounded for theta so that exactly vertical and horizontal are in
93 // the middle of a bucket. The Modulo takes care of the wrap-around.
94 int ThetaBucket(int theta) const {
95 int bucket = DivRounded(theta * theta_buckets_, kIntFeatureExtent);
96 return Modulo(bucket, theta_buckets_);
97 }
98 // Returns an INT_FEATURE_STRUCT corresponding to the given buckets.
99 INT_FEATURE_STRUCT PositionFromBuckets(int x, int y, int theta) const;
100
101 // Feature space definition - serialized.
102 uinT8 x_buckets_;
103 uinT8 y_buckets_;
104 uinT8 theta_buckets_;
105 };
106
107 } // namespace tesseract.
108
109
110 #endif // TESSERACT_CLASSIFY_INTFEATURESPACE_H__