1 /* 2 * Copyright (C) 2008 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 /* ---- includes ----------------------------------------------------------- */ 18 19 #include "b_BasicEm/Int16Arr.h" 20 #include "b_BasicEm/Math.h" 21 #include "b_ImageEm/HistoEq.h" 22 #include "b_ImageEm/UInt8Image.h" 23 24 /* ---- typedefs ----------------------------------------------------------- */ 25 26 /* ---- constants ---------------------------------------------------------- */ 27 28 /* ------------------------------------------------------------------------- */ 29 30 /* ========================================================================= */ 31 /* */ 32 /* ---- \ghd{ auxiliary functions } ---------------------------------------- */ 33 /* */ 34 /* ========================================================================= */ 35 36 /** Computes grey level histogram of given image. */ 37 void bim_createHisto( struct bbs_Context* cpA, 38 uint16* histoPtrA, 39 const struct bim_UInt8Image* imagePtrA ) 40 { 41 uint32 iL; 42 uint16* dstPtrL; 43 const uint8* srcPtrL; 44 45 /* init histogram array with 0 */ 46 dstPtrL = histoPtrA; 47 for( iL = 256; iL > 0; iL-- ) 48 { 49 *dstPtrL++ = 0; 50 } 51 52 /* calculate histogram */ 53 srcPtrL = imagePtrA->arrE.arrPtrE; 54 dstPtrL = histoPtrA; 55 for( iL = imagePtrA->arrE.sizeE; iL > 0; iL-- ) 56 { 57 dstPtrL[ *srcPtrL++ ]++; 58 } 59 } 60 61 /* ------------------------------------------------------------------------- */ 62 63 /** Computes grey level histogram of given image. */ 64 void bim_createHistoOfSection( struct bbs_Context* cpA, 65 uint16* histoPtrA, 66 const struct bts_Int16Rect* sectionPtrA, 67 const struct bim_UInt8Image* imagePtrA ) 68 { 69 uint32 xL, yL; 70 const uint8* srcPtrL; 71 uint16* dstPtrL; 72 struct bts_Int16Rect sectionL = *sectionPtrA; 73 uint32 sectWidthL; 74 uint32 sectHeightL; 75 int32 imgWidthL = imagePtrA->widthE; 76 int32 imgHeightL = imagePtrA->heightE; 77 78 /* adjustments */ 79 sectionL.x1E = bbs_max( 0, sectionL.x1E ); 80 sectionL.x1E = bbs_min( imgWidthL, sectionL.x1E ); 81 sectionL.x2E = bbs_max( 0, sectionL.x2E ); 82 sectionL.x2E = bbs_min( imgWidthL, sectionL.x2E ); 83 sectionL.y1E = bbs_max( 0, sectionL.y1E ); 84 sectionL.y1E = bbs_min( imgHeightL, sectionL.y1E ); 85 sectionL.y2E = bbs_max( 0, sectionL.y2E ); 86 sectionL.y2E = bbs_min( imgHeightL, sectionL.y2E ); 87 88 sectWidthL = sectionL.x2E - sectionL.x1E; 89 sectHeightL = sectionL.y2E - sectionL.y1E; 90 91 /* init histogram with 0 */ 92 dstPtrL = histoPtrA; 93 for( xL = 256; xL > 0; xL-- ) 94 { 95 *dstPtrL++ = 0; 96 } 97 98 /* calculate histogram */ 99 srcPtrL = imagePtrA->arrE.arrPtrE + sectionL.y1E * imgWidthL + sectionL.x1E; 100 dstPtrL = histoPtrA; 101 for( yL = 0; yL < sectHeightL; yL++ ) 102 { 103 for( xL = 0; xL < sectWidthL; xL++ ) 104 { 105 dstPtrL[ *srcPtrL++ ]++; 106 } 107 srcPtrL += imgWidthL - sectWidthL; 108 } 109 } 110 111 /* ------------------------------------------------------------------------- */ 112 113 /** equalize image using given histogram */ 114 void bim_equalize( struct bbs_Context* cpA, 115 struct bim_UInt8Image* imagePtrA, 116 const uint16* histoPtrA ) 117 { 118 uint32 kL; 119 uint32 sumL = 0; 120 uint32 totalSumL = 0; 121 const uint16* histoArrPtrL; 122 uint8* dstPtrL; 123 uint8 mappingL[ 256 ]; 124 125 /* determine number of counts in histogram */ 126 histoArrPtrL = histoPtrA; 127 for( kL = 256; kL > 0; kL-- ) 128 { 129 totalSumL += *histoArrPtrL++; 130 } 131 132 if( totalSumL == 0 ) totalSumL = 1; 133 134 /* compute transfer function (cumulative histogram) */ 135 histoArrPtrL = histoPtrA; 136 for( kL = 0; kL < 256; kL++ ) 137 { 138 sumL += *histoArrPtrL++; 139 mappingL[ kL ] = ( sumL * 255 ) / totalSumL; 140 } 141 142 /* remap pixel values */ 143 dstPtrL = imagePtrA->arrE.arrPtrE; 144 for( kL = imagePtrA->arrE.sizeE; kL > 0; kL-- ) 145 { 146 *dstPtrL = mappingL[ *dstPtrL ]; 147 dstPtrL++; 148 } 149 } 150 151 /* ------------------------------------------------------------------------- */ 152 153 /* ========================================================================= */ 154 /* */ 155 /* ---- \ghd{ external functions } ----------------------------------------- */ 156 /* */ 157 /* ========================================================================= */ 158 159 /* ------------------------------------------------------------------------- */ 160 161 void bim_UInt8Image_equalize( struct bbs_Context* cpA, 162 struct bim_UInt8Image* imagePtrA ) 163 { 164 uint16 histogramL[ 256 ]; 165 bim_createHisto( cpA, histogramL, imagePtrA ); 166 bim_equalize( cpA, imagePtrA, histogramL ); 167 } 168 169 /* ------------------------------------------------------------------------- */ 170 171 void bim_UInt8Image_equalizeSection( struct bbs_Context* cpA, 172 struct bim_UInt8Image* imagePtrA, 173 const struct bts_Int16Rect* sectionPtrA ) 174 { 175 uint16 histogramL[ 256 ]; 176 bim_createHistoOfSection( cpA, histogramL, sectionPtrA, imagePtrA ); 177 bim_equalize( cpA, imagePtrA, histogramL ); 178 } 179 180 /* ========================================================================= */ 181
