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normfeat.cpp
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1 /******************************************************************************
2 ** Filename: normfeat.c
3 ** Purpose: Definition of char normalization features.
4 ** Author: Dan Johnson
5 ** History: 12/14/90, DSJ, Created.
6 **
7 ** (c) Copyright Hewlett-Packard Company, 1988.
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 ******************************************************************************/
21 #include "normfeat.h"
22
23 #include "intfx.h"
24 #include "featdefs.h"
25 #include "mfoutline.h"
26
31 // Return the length of the outline in baseline normalized form.
32 FLOAT32 ActualOutlineLength(FEATURE Feature) {
33 return (Feature->Params[CharNormLength] * LENGTH_COMPRESSION);
34 }
35
36
37 /*---------------------------------------------------------------------------*/
38 // Return the character normalization feature for a blob.
39 //
40 // The features returned are in a scale where the x-height has been
41 // normalized to live in the region y = [-0.25 .. 0.25]. Example ranges
42 // for English below are based on the Linux font collection on 2009-12-04:
43 //
44 // Params[CharNormY]
45 // The y coordinate of the grapheme's centroid.
46 // English: [-0.27, 0.71]
47 //
48 // Params[CharNormLength]
49 // The length of the grapheme's outline (tiny segments discarded),
50 // divided by 10.0=LENGTH_COMPRESSION.
51 // English: [0.16, 0.85]
52 //
53 // Params[CharNormRx]
54 // The radius of gyration about the x axis, as measured from CharNormY.
55 // English: [0.011, 0.34]
56 //
57 // Params[CharNormRy]
58 // The radius of gyration about the y axis, as measured from
59 // the x center of the grapheme's bounding box.
60 // English: [0.011, 0.31]
61 //
62 FEATURE_SET ExtractCharNormFeatures(TBLOB *blob, const DENORM& denorm) {
63 FEATURE_SET feature_set = NewFeatureSet(1);
64 FEATURE feature = NewFeature(&CharNormDesc);
65
66 INT_FEATURE_ARRAY blfeatures;
67 INT_FEATURE_ARRAY cnfeatures;
68 INT_FX_RESULT_STRUCT FXInfo;
69
70 ExtractIntFeat(blob, denorm, blfeatures, cnfeatures, &FXInfo);
71
72 feature->Params[CharNormY] =
73 MF_SCALE_FACTOR * (FXInfo.Ymean - BASELINE_OFFSET);
74 feature->Params[CharNormLength] =
75 MF_SCALE_FACTOR * FXInfo.Length / LENGTH_COMPRESSION;
76 feature->Params[CharNormRx] = MF_SCALE_FACTOR * FXInfo.Rx;
77 feature->Params[CharNormRy] = MF_SCALE_FACTOR * FXInfo.Ry;
78
79 AddFeature(feature_set, feature);
80
81 return feature_set;
82 } /* ExtractCharNormFeatures */