401 lines
12 KiB
C++
401 lines
12 KiB
C++
#include <stdlib.h>
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#include <math.h>
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#include "EtcFilter.h"
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namespace Etc
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{
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static const double PiConst = 3.14159265358979323846;
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inline double sinc(double x)
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{
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if ( x == 0.0 )
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{
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return 1.0;
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}
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return sin(PiConst * x) / (PiConst * x);
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}
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//inline float sincf( float x )
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//{
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// x *= F_PI;
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// if (x < 0.01f && x > -0.01f)
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// {
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// return 1.0f + x*x*(-1.0f/6.0f + x*x*1.0f/120.0f);
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// }
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//
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// return sinf(x)/x;
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//}
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//
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//double bessel0(double x)
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//{
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// const double EPSILON_RATIO = 1E-16;
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// double xh, sum, pow, ds;
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// int k;
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//
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// xh = 0.5 * x;
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// sum = 1.0;
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// pow = 1.0;
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// k = 0;
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// ds = 1.0;
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// while (ds > sum * EPSILON_RATIO)
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// {
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// ++k;
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// pow = pow * (xh / k);
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// ds = pow * pow;
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// sum = sum + ds;
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// }
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//
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// return sum;
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//}
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//**--------------------------------------------------------------------------
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//** Name: kaiser(double alpha, double half_width, double x)
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//** Returns:
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//** Description: Alpha controls shape of filter. We are using 4.
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//**--------------------------------------------------------------------------
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//inline double kaiser(double alpha, double half_width, double x)
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//{
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// double ratio = (x / half_width);
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// return bessel0(alpha * sqrt(1 - ratio * ratio)) / bessel0(alpha);
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//}
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//
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//float Filter_Lanczos4Sinc(float x)
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//{
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// if (x <= -4.0f || x >= 4.0f) // half-width of 4
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// {
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// return 0.0;
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// }
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//
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// return sinc(0.875f * x) * sinc(0.25f * x);
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//}
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//
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//double Filter_Kaiser4( double t )
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//{
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// return kaiser( 4.0, 3.0, t);
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//}
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//
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//double Filter_KaiserOptimal( double t )
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//{
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// return kaiser( 8.93, 3.0f, t);
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//}
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double FilterLanczos3( double t )
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{
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if ( t <= -3.0 || t >= 3.0 )
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{
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return 0.0;
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}
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return sinc( t ) * sinc( t / 3.0 );
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}
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double FilterBox( double t )
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{
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return ( t > -0.5 && t < 0.5) ? 1.0 : 0.0;
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}
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double FilterLinear( double t )
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{
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if (t < 0.0) t = -t;
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return (t < 1.0) ? (1.0 - t) : 0.0;
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}
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//**--------------------------------------------------------------------------
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//** Name: CalcContributions( int srcSize,
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//** int destSize,
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//** double filterSize,
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//** bool wrap,
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//** double (*FilterProc)(double),
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//** FilterWeights contrib[] )
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//** Returns: void
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//** Description:
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//**--------------------------------------------------------------------------
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void CalcContributions( int srcSize, int destSize, double filterSize, bool wrap, double (*FilterProc)(double), FilterWeights contrib[] )
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{
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double scale;
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double filterScale;
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double center;
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double totalWeight;
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double weight;
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int iRight;
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int iLeft;
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int iDest;
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scale = (double)destSize / srcSize;
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if ( scale < 1.0 )
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{
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filterSize = filterSize / scale;
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filterScale = scale;
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}
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else
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{
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filterScale = 1.0;
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}
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if ( filterSize > (double)MaxFilterSize )
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{
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filterSize = (double)MaxFilterSize;
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}
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for ( iDest = 0; iDest < destSize; ++iDest )
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{
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center = (double)iDest / scale;
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iLeft = (int)ceil(center - filterSize);
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iRight = (int)floor(center + filterSize);
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if ( !wrap )
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{
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if ( iLeft < 0 )
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{
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iLeft = 0;
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}
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if ( iRight >= srcSize )
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{
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iRight = srcSize - 1;
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}
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}
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int numWeights = iRight - iLeft + 1;
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contrib[iDest].first = iLeft;
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contrib[iDest].numWeights = numWeights;
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totalWeight = 0;
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double t = ((double)iLeft - center) * filterScale;
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for (int i = 0; i < numWeights; i++)
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{
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weight = (*FilterProc)(t) * filterScale;
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totalWeight += weight;
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contrib[iDest].weight[i] = weight;
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t += filterScale;
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}
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//**--------------------------------------------------------
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//** Normalize weights by dividing by the sum of the weights
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//**--------------------------------------------------------
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if ( totalWeight > 0.0 )
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{
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for ( int i = 0; i < numWeights; i++)
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{
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contrib[iDest].weight[i] /= totalWeight;
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}
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}
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}
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}
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//**-------------------------------------------------------------------------
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//** Name: Filter_TwoPass( RGBCOLOR *pSrcImage,
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//** int srcWidth, int srcHeight,
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//** RGBCOLOR *pDestImage,
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//** int destWidth, int destHeight,
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//** double (*FilterProc)(double) )
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//** Returns: 0 on failure and 1 on success
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//** Description: Filters a 2d image with a two pass filter by averaging the
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//** weighted contributions of the pixels within the filter region. The
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//** contributions are determined by a weighting function parameter.
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//**-------------------------------------------------------------------------
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int FilterTwoPass( RGBCOLOR *pSrcImage, int srcWidth, int srcHeight,
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RGBCOLOR *pDestImage, int destWidth, int destHeight, unsigned int wrapFlags, double (*FilterProc)(double) )
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{
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FilterWeights *contrib;
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RGBCOLOR *pPixel;
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RGBCOLOR *pSrcPixel;
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RGBCOLOR *pTempImage;
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int iRow;
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int iCol;
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int iSrcCol;
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int iSrcRow;
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int iWeight;
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double dRed;
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double dGreen;
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double dBlue;
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double dAlpha;
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double filterSize = 3.0;
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int maxDim = (srcWidth>srcHeight)?srcWidth:srcHeight;
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contrib = (FilterWeights*)malloc(maxDim * sizeof(FilterWeights));
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//**------------------------------------------------------------------------
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//** Need to create a temporary image to stuff the horizontally scaled image
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//**------------------------------------------------------------------------
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pTempImage = (RGBCOLOR *)malloc( destWidth * srcHeight * sizeof(RGBCOLOR) );
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if ( pTempImage == NULL )
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{
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return 0;
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}
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//**-------------------------------------------------------
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//** Horizontally filter the image into the temporary image
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//**-------------------------------------------------------
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bool bWrapHorizontal = !!(wrapFlags&FILTER_WRAP_X);
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CalcContributions( srcWidth, destWidth, filterSize, bWrapHorizontal, FilterProc, contrib );
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for ( iRow = 0; iRow < srcHeight; iRow++ )
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{
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for ( iCol = 0; iCol < destWidth; iCol++ )
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{
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dRed = 0;
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dGreen = 0;
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dBlue = 0;
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dAlpha = 0;
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for ( iWeight = 0; iWeight < contrib[iCol].numWeights; iWeight++ )
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{
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iSrcCol = iWeight + contrib[iCol].first;
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if (bWrapHorizontal)
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{
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iSrcCol = (iSrcCol < 0) ? (srcWidth + iSrcCol) : (iSrcCol >= srcWidth) ? (iSrcCol - srcWidth) : iSrcCol;
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}
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pSrcPixel = pSrcImage + (iRow * srcWidth) + iSrcCol;
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dRed += contrib[iCol].weight[iWeight] * pSrcPixel->rgba[0];
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dGreen += contrib[iCol].weight[iWeight] * pSrcPixel->rgba[1];
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dBlue += contrib[iCol].weight[iWeight] * pSrcPixel->rgba[2];
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dAlpha += contrib[iCol].weight[iWeight] * pSrcPixel->rgba[3];
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}
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pPixel = pTempImage + (iRow * destWidth) + iCol;
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pPixel->rgba[0] = static_cast<unsigned char>(std::max(0.0, std::min(255.0, dRed)));
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pPixel->rgba[1] = static_cast<unsigned char>(std::max(0.0, std::min(255.0, dGreen)));
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pPixel->rgba[2] = static_cast<unsigned char>(std::max(0.0, std::min(255.0, dBlue)));
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pPixel->rgba[3] = static_cast<unsigned char>(std::max(0.0, std::min(255.0, dAlpha)));
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}
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}
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//**-------------------------------------------------------
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//** Vertically filter the image into the destination image
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//**-------------------------------------------------------
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bool bWrapVertical = !!(wrapFlags&FILTER_WRAP_Y);
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CalcContributions(srcHeight, destHeight, filterSize, bWrapVertical, FilterProc, contrib);
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for ( iCol = 0; iCol < destWidth; iCol++ )
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{
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for ( iRow = 0; iRow < destHeight; iRow++ )
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{
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dRed = 0;
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dGreen = 0;
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dBlue = 0;
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dAlpha = 0;
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for ( iWeight = 0; iWeight < contrib[iRow].numWeights; iWeight++ )
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{
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iSrcRow = iWeight + contrib[iRow].first;
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if (bWrapVertical)
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{
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iSrcRow = (iSrcRow < 0) ? (srcHeight + iSrcRow) : (iSrcRow >= srcHeight) ? (iSrcRow - srcHeight) : iSrcRow;
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}
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pSrcPixel = pTempImage + (iSrcRow * destWidth) + iCol;
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dRed += contrib[iRow].weight[iWeight] * pSrcPixel->rgba[0];
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dGreen += contrib[iRow].weight[iWeight] * pSrcPixel->rgba[1];
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dBlue += contrib[iRow].weight[iWeight] * pSrcPixel->rgba[2];
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dAlpha += contrib[iRow].weight[iWeight] * pSrcPixel->rgba[3];
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}
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pPixel = pDestImage + (iRow * destWidth) + iCol;
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pPixel->rgba[0] = (unsigned char)(std::max( 0.0, std::min( 255.0, dRed)));
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pPixel->rgba[1] = (unsigned char)(std::max( 0.0, std::min( 255.0, dGreen)));
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pPixel->rgba[2] = (unsigned char)(std::max( 0.0, std::min( 255.0, dBlue)));
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pPixel->rgba[3] = (unsigned char)(std::max( 0.0, std::min( 255.0, dAlpha)));
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}
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}
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free( pTempImage );
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free( contrib );
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return 1;
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}
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//**-------------------------------------------------------------------------
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//** Name: FilterResample(RGBCOLOR *pSrcImage, int srcWidth, int srcHeight,
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//** RGBCOLOR *pDstImage, int dstWidth, int dstHeight)
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//** Returns: 1
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//** Description: This function runs a 2d box filter over the srouce image
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//** to produce the destination image.
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//**-------------------------------------------------------------------------
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void FilterResample( RGBCOLOR *pSrcImage, int srcWidth, int srcHeight,
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RGBCOLOR *pDstImage, int dstWidth, int dstHeight )
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{
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int iRow;
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int iCol;
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int iSampleRow;
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int iSampleCol;
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int iFirstSampleRow;
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int iFirstSampleCol;
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int iLastSampleRow;
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int iLastSampleCol;
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int red;
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int green;
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int blue;
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int alpha;
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int samples;
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float xScale;
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float yScale;
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RGBCOLOR *pSrcPixel;
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RGBCOLOR *pDstPixel;
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xScale = (float)srcWidth / dstWidth;
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yScale = (float)srcHeight / dstHeight;
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for ( iRow = 0; iRow < dstHeight; iRow++ )
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{
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for ( iCol = 0; iCol < dstWidth; iCol++ )
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{
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iFirstSampleRow = (int)(iRow * yScale);
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iLastSampleRow = (int)ceil(iFirstSampleRow + yScale - 1);
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if ( iLastSampleRow >= srcHeight )
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{
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iLastSampleRow = srcHeight - 1;
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}
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iFirstSampleCol = (int)(iCol * xScale);
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iLastSampleCol = (int)ceil(iFirstSampleCol + xScale - 1);
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if ( iLastSampleCol >= srcWidth )
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{
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iLastSampleCol = srcWidth - 1;
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}
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samples = 0;
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red = 0;
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green = 0;
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blue = 0;
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alpha = 0;
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for ( iSampleRow = iFirstSampleRow; iSampleRow <= iLastSampleRow; iSampleRow++ )
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{
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for ( iSampleCol = iFirstSampleCol; iSampleCol <= iLastSampleCol; iSampleCol++ )
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{
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pSrcPixel = pSrcImage + iSampleRow * srcWidth + iSampleCol;
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red += pSrcPixel->rgba[0];
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green += pSrcPixel->rgba[1];
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blue += pSrcPixel->rgba[2];
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alpha += pSrcPixel->rgba[3];
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samples++;
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}
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}
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pDstPixel = pDstImage + iRow * dstWidth + iCol;
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if ( samples > 0 )
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{
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pDstPixel->rgba[0] = static_cast<uint8_t>(red / samples);
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pDstPixel->rgba[1] = static_cast<uint8_t>(green / samples);
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pDstPixel->rgba[2] = static_cast<uint8_t>(blue / samples);
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pDstPixel->rgba[3] = static_cast<uint8_t>(alpha / samples);
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}
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else
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{
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pDstPixel->rgba[0] = static_cast<uint8_t>(red);
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pDstPixel->rgba[1] = static_cast<uint8_t>(green);
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pDstPixel->rgba[2] = static_cast<uint8_t>(blue);
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pDstPixel->rgba[3] = static_cast<uint8_t>(alpha);
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}
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}
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}
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}
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} |