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76 lines
3.0 KiB
C++
76 lines
3.0 KiB
C++
/******************************************************************************
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** Filename: normfeat.c
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** Purpose: Definition of char normalization features.
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** Author: Dan Johnson
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** History: 12/14/90, DSJ, Created.
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**
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** (c) Copyright Hewlett-Packard Company, 1988.
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** Licensed under the Apache License, Version 2.0 (the "License");
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** you may not use this file except in compliance with the License.
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** You may obtain a copy of the License at
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** http://www.apache.org/licenses/LICENSE-2.0
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** Unless required by applicable law or agreed to in writing, software
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** distributed under the License is distributed on an "AS IS" BASIS,
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** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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** See the License for the specific language governing permissions and
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** limitations under the License.
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******************************************************************************/
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/*----------------------------------------------------------------------------
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Include Files and Type Defines
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----------------------------------------------------------------------------*/
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#include "normfeat.h"
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#include "intfx.h"
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#include "featdefs.h"
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#include "mfoutline.h"
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/*----------------------------------------------------------------------------
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Public Code
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----------------------------------------------------------------------------*/
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/** Return the length of the outline in baseline normalized form. */
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FLOAT32 ActualOutlineLength(FEATURE Feature) {
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return (Feature->Params[CharNormLength] * LENGTH_COMPRESSION);
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}
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/**
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* Return the character normalization feature for a blob.
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*
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* The features returned are in a scale where the x-height has been
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* normalized to live in the region y = [-0.25 .. 0.25]. Example ranges
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* for English below are based on the Linux font collection on 2009-12-04:
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*
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* - Params[CharNormY]
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* - The y coordinate of the grapheme's centroid.
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* - English: [-0.27, 0.71]
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*
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* - Params[CharNormLength]
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* - The length of the grapheme's outline (tiny segments discarded),
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* divided by 10.0=LENGTH_COMPRESSION.
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* - English: [0.16, 0.85]
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*
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* - Params[CharNormRx]
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* - The radius of gyration about the x axis, as measured from CharNormY.
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* - English: [0.011, 0.34]
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*
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* - Params[CharNormRy]
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* - The radius of gyration about the y axis, as measured from
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* the x center of the grapheme's bounding box.
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* - English: [0.011, 0.31]
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*/
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FEATURE_SET ExtractCharNormFeatures(const INT_FX_RESULT_STRUCT& fx_info) {
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FEATURE_SET feature_set = NewFeatureSet(1);
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FEATURE feature = NewFeature(&CharNormDesc);
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feature->Params[CharNormY] =
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MF_SCALE_FACTOR * (fx_info.Ymean - kBlnBaselineOffset);
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feature->Params[CharNormLength] =
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MF_SCALE_FACTOR * fx_info.Length / LENGTH_COMPRESSION;
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feature->Params[CharNormRx] = MF_SCALE_FACTOR * fx_info.Rx;
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feature->Params[CharNormRy] = MF_SCALE_FACTOR * fx_info.Ry;
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AddFeature(feature_set, feature);
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return feature_set;
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} /* ExtractCharNormFeatures */
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