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mhugentmhugent
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Consider alpha channel for bilinear and cubic resampling
1 parent cc9bc52 commit be97ca4

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3 files changed

+97
-47
lines changed

3 files changed

+97
-47
lines changed

‎src/core/raster/qgsbilinearrasterresampler.cpp‎

Lines changed: 18 additions & 14 deletions
Original file line numberDiff line numberDiff line change
@@ -51,47 +51,47 @@ void QgsBilinearRasterResampler::resample( const QImage& srcImage, QImage& dstIm
5151
u = currentSrcCol - currentSrcColInt;
5252

5353
//handle eight edge-cases
54-
if( currentSrcRowInt < 0 || currentSrcRowInt >= (srcImage.height() - 1) || currentSrcColInt < 0 || currentSrcColInt >= (srcImage.width() - 1) )
54+
if ( currentSrcRowInt < 0 || currentSrcRowInt >= ( srcImage.height() - 1 ) || currentSrcColInt < 0 || currentSrcColInt >= ( srcImage.width() - 1 ) )
5555
{
5656
//pixels at the border of the source image needs to be handled in a special way
57-
if( currentSrcRowInt < 0 && currentSrcColInt < 0 )
57+
if ( currentSrcRowInt < 0 && currentSrcColInt < 0 )
5858
{
59-
dstImage.setPixel( j, i, srcImage.pixel(0, 0) );
59+
dstImage.setPixel( j, i, srcImage.pixel( 0, 0 ) );
6060
}
61-
else if( currentSrcRowInt < 0 && currentSrcColInt >= ( srcImage.width() - 1 ) )
61+
else if ( currentSrcRowInt < 0 && currentSrcColInt >= ( srcImage.width() - 1 ) )
6262
{
6363
dstImage.setPixel( j, i, srcImage.pixel( srcImage.width() - 1, 0 ) );
6464
}
65-
else if( currentSrcRowInt >= (srcImage.height() - 1) && currentSrcColInt >= ( srcImage.width() - 1 ) )
65+
else if ( currentSrcRowInt >= ( srcImage.height() - 1 ) && currentSrcColInt >= ( srcImage.width() - 1 ) )
6666
{
6767
dstImage.setPixel( j, i, srcImage.pixel( srcImage.width() - 1, srcImage.height() - 1 ) );
6868
}
69-
else if( currentSrcRowInt >= (srcImage.height() - 1) && currentSrcColInt < 0 )
69+
else if ( currentSrcRowInt >= ( srcImage.height() - 1 ) && currentSrcColInt < 0 )
7070
{
7171
dstImage.setPixel( j, i, srcImage.pixel( 0, srcImage.height() - 1 ) );
7272
}
73-
else if( currentSrcRowInt < 0 )
73+
else if ( currentSrcRowInt < 0 )
7474
{
7575
px1 = srcImage.pixel( currentSrcColInt, 0 );
7676
px2 = srcImage.pixel( currentSrcColInt + 1, 0 );
7777
dstImage.setPixel( j, i, resampleColorValue( u, px1, px2 ) );
7878
}
79-
else if( currentSrcRowInt >= (srcImage.height() - 1) )
79+
else if ( currentSrcRowInt >= ( srcImage.height() - 1 ) )
8080
{
8181
px1 = srcImage.pixel( currentSrcColInt, srcImage.height() - 1 );
8282
px2 = srcImage.pixel( currentSrcColInt + 1, srcImage.height() - 1 );
8383
dstImage.setPixel( j, i, resampleColorValue( u, px1, px2 ) );
8484
}
85-
else if( currentSrcColInt < 0 )
85+
else if ( currentSrcColInt < 0 )
8686
{
8787
px1 = srcImage.pixel( 0, currentSrcRowInt );
88-
px2 = srcImage.pixel( 0, currentSrcRowInt + 1);
88+
px2 = srcImage.pixel( 0, currentSrcRowInt + 1 );
8989
dstImage.setPixel( j, i, resampleColorValue( v, px1, px2 ) );
9090
}
91-
else if( currentSrcColInt >= ( srcImage.width() - 1 ) )
91+
else if ( currentSrcColInt >= ( srcImage.width() - 1 ) )
9292
{
9393
px1 = srcImage.pixel( srcImage.width() - 1, currentSrcRowInt );
94-
px2 = srcImage.pixel( srcImage.width() - 1, currentSrcRowInt + 1);
94+
px2 = srcImage.pixel( srcImage.width() - 1, currentSrcRowInt + 1 );
9595
dstImage.setPixel( j, i, resampleColorValue( v, px1, px2 ) );
9696
}
9797
currentSrcCol += nSrcPerDstX;
@@ -114,10 +114,14 @@ QRgb QgsBilinearRasterResampler::resampleColorValue( double u, double v, QRgb co
114114
int red = bilinearInterpolation( u, v, qRed( col1 ), qRed( col2 ), qRed( col3 ), qRed( col4 ) );
115115
int green = bilinearInterpolation( u, v, qGreen( col1 ), qGreen( col2 ), qGreen( col3 ), qGreen( col4 ) );
116116
int blue = bilinearInterpolation( u, v, qBlue( col1 ), qBlue( col2 ), qBlue( col3 ), qBlue( col4 ) );
117-
return qRgb( red, green, blue );
117+
int alpha = bilinearInterpolation( u, v, qAlpha( col1 ), qAlpha( col2 ), qAlpha( col3 ), qAlpha( col4 ) );
118+
return qRgba( red, green, blue, alpha );
118119
}
119120

120121
QRgb QgsBilinearRasterResampler::resampleColorValue( double u, QRgb col1, QRgb col2 ) const
121122
{
122-
return qRgb( qRed( col1 ) * ( 1 - u ) + qRed( col2 ) * u, qGreen( col1 ) * ( 1 - u ) + qGreen( col2 ) * u, qBlue( col1 ) * ( 1 - u ) + qBlue( col2 ) * u );
123+
return qRgba( qRed( col1 ) * ( 1 - u ) + qRed( col2 ) * u,
124+
qGreen( col1 ) * ( 1 - u ) + qGreen( col2 ) * u,
125+
qBlue( col1 ) * ( 1 - u ) + qBlue( col2 ) * u,
126+
qAlpha( col1 ) * ( 1 - u ) + qAlpha( col2 ) * u );
123127
}

‎src/core/raster/qgscubicrasterresampler.cpp‎

Lines changed: 71 additions & 30 deletions
Original file line numberDiff line numberDiff line change
@@ -37,6 +37,7 @@ void QgsCubicRasterResampler::resample( const QImage& srcImage, QImage& dstImage
3737
int* redMatrix = new int[ nCols * nRows ];
3838
int* greenMatrix = new int[ nCols * nRows ];
3939
int* blueMatrix = new int[ nCols * nRows ];
40+
int* alphaMatrix = new int[ nCols * nRows ];
4041

4142
for ( int i = 0; i < nRows; ++i )
4243
{
@@ -46,6 +47,7 @@ void QgsCubicRasterResampler::resample( const QImage& srcImage, QImage& dstImage
4647
redMatrix[pos] = qRed( px );
4748
greenMatrix[pos] = qGreen( px );
4849
blueMatrix[pos] = qBlue( px );
50+
alphaMatrix[pos] = qAlpha( px );
4951
++pos;
5052
}
5153
}
@@ -57,6 +59,8 @@ void QgsCubicRasterResampler::resample( const QImage& srcImage, QImage& dstImage
5759
xDerivativeMatrix( nCols, nRows, xDerivativeMatrixGreen, greenMatrix );
5860
double* xDerivativeMatrixBlue = new double[ nCols * nRows ];
5961
xDerivativeMatrix( nCols, nRows, xDerivativeMatrixBlue, blueMatrix );
62+
double* xDerivativeMatrixAlpha = new double[ nCols * nRows ];
63+
xDerivativeMatrix( nCols, nRows, xDerivativeMatrixAlpha, alphaMatrix );
6064

6165
//derivative y
6266
double* yDerivativeMatrixRed = new double[ nCols * nRows ];
@@ -65,6 +69,8 @@ void QgsCubicRasterResampler::resample( const QImage& srcImage, QImage& dstImage
6569
yDerivativeMatrix( nCols, nRows, yDerivativeMatrixGreen, greenMatrix );
6670
double* yDerivativeMatrixBlue = new double[ nCols * nRows ];
6771
yDerivativeMatrix( nCols, nRows, yDerivativeMatrixBlue, blueMatrix );
72+
double* yDerivativeMatrixAlpha = new double[ nCols * nRows ];
73+
yDerivativeMatrix( nCols, nRows, yDerivativeMatrixAlpha, alphaMatrix );
6874

6975
//compute output
7076
double nSrcPerDstX = ( double ) srcImage.width() / ( double ) dstImage.width();
@@ -77,7 +83,7 @@ void QgsCubicRasterResampler::resample( const QImage& srcImage, QImage& dstImage
7783
int lastSrcColInt = -1;
7884
int lastSrcRowInt = -1;
7985

80-
int r, g, b;
86+
int r, g, b, a;
8187
//bernstein polynomials
8288
double bp0u, bp1u, bp2u, bp3u, bp0v, bp1v, bp2v, bp3v;
8389
double u, v;
@@ -119,16 +125,17 @@ void QgsCubicRasterResampler::resample( const QImage& srcImage, QImage& dstImage
119125
px1 = srcImage.pixel( currentSrcColInt, 0 );
120126
px2 = srcImage.pixel( currentSrcColInt + 1, 0 );
121127
dstImage.setPixel( j, i, curveInterpolation( px1, px2, u, xDerivativeMatrixRed[ currentSrcColInt ], xDerivativeMatrixGreen[ currentSrcColInt ],
122-
xDerivativeMatrixBlue[ currentSrcColInt ], xDerivativeMatrixRed[ currentSrcColInt + 1 ], xDerivativeMatrixGreen[ currentSrcColInt + 1 ],
123-
xDerivativeMatrixBlue[ currentSrcColInt + 1 ] ) );
128+
xDerivativeMatrixBlue[ currentSrcColInt ], xDerivativeMatrixAlpha[ currentSrcColInt ], xDerivativeMatrixRed[ currentSrcColInt + 1 ], xDerivativeMatrixGreen[ currentSrcColInt + 1 ],
129+
xDerivativeMatrixBlue[ currentSrcColInt + 1 ], xDerivativeMatrixAlpha[ currentSrcColInt + 1 ] ) );
124130
}
125131
else if ( currentSrcRowInt >= ( srcImage.height() - 1 ) )
126132
{
127133
int idx = ( srcImage.height() - 1 ) * srcImage.width() + currentSrcColInt;
128134
px1 = srcImage.pixel( currentSrcColInt, srcImage.height() - 1 );
129135
px2 = srcImage.pixel( currentSrcColInt + 1, srcImage.height() - 1 );
130136
dstImage.setPixel( j, i, curveInterpolation( px1, px2, u, xDerivativeMatrixRed[ idx ], xDerivativeMatrixGreen[ idx ], xDerivativeMatrixBlue[idx],
131-
xDerivativeMatrixRed[ idx + 1 ], xDerivativeMatrixGreen[ idx + 1 ], xDerivativeMatrixBlue[idx + 1] ) );
137+
xDerivativeMatrixAlpha[idx], xDerivativeMatrixRed[ idx + 1 ], xDerivativeMatrixGreen[ idx + 1 ], xDerivativeMatrixBlue[idx + 1],
138+
xDerivativeMatrixAlpha[idx + 1] ) );
132139
}
133140
else if ( currentSrcColInt < 0 )
134141
{
@@ -137,7 +144,8 @@ void QgsCubicRasterResampler::resample( const QImage& srcImage, QImage& dstImage
137144
px1 = srcImage.pixel( 0, currentSrcRowInt );
138145
px2 = srcImage.pixel( 0, currentSrcRowInt + 1 );
139146
dstImage.setPixel( j, i, curveInterpolation( px1, px2, v, yDerivativeMatrixRed[ idx1 ], yDerivativeMatrixGreen[ idx1 ], yDerivativeMatrixBlue[ idx1],
140-
yDerivativeMatrixRed[ idx2 ], yDerivativeMatrixGreen[ idx2 ], yDerivativeMatrixBlue[ idx2] ) );
147+
yDerivativeMatrixAlpha[ idx1], yDerivativeMatrixRed[ idx2 ], yDerivativeMatrixGreen[ idx2 ], yDerivativeMatrixBlue[ idx2],
148+
yDerivativeMatrixAlpha[ idx2] ) );
141149
}
142150
else if ( currentSrcColInt >= ( srcImage.width() - 1 ) )
143151
{
@@ -146,7 +154,8 @@ void QgsCubicRasterResampler::resample( const QImage& srcImage, QImage& dstImage
146154
px1 = srcImage.pixel( srcImage.width() - 1, currentSrcRowInt );
147155
px2 = srcImage.pixel( srcImage.width() - 1, currentSrcRowInt + 1 );
148156
dstImage.setPixel( j, i, curveInterpolation( px1, px2, v, yDerivativeMatrixRed[ idx1 ], yDerivativeMatrixGreen[ idx1 ], yDerivativeMatrixBlue[ idx1],
149-
yDerivativeMatrixRed[ idx2 ], yDerivativeMatrixGreen[ idx2 ], yDerivativeMatrixBlue[ idx2] ) );
157+
yDerivativeMatrixAlpha[ idx1], yDerivativeMatrixRed[ idx2 ], yDerivativeMatrixGreen[ idx2 ], yDerivativeMatrixBlue[ idx2],
158+
yDerivativeMatrixAlpha[ idx2] ) );
150159
}
151160
currentSrcCol += nSrcPerDstX;
152161
continue;
@@ -155,9 +164,9 @@ void QgsCubicRasterResampler::resample( const QImage& srcImage, QImage& dstImage
155164
//first update the control points if necessary
156165
if ( currentSrcColInt != lastSrcColInt || currentSrcRowInt != lastSrcRowInt )
157166
{
158-
calculateControlPoints( nCols, nRows, currentSrcRowInt, currentSrcColInt, redMatrix, greenMatrix, blueMatrix,
159-
xDerivativeMatrixRed, xDerivativeMatrixGreen, xDerivativeMatrixBlue,
160-
yDerivativeMatrixRed, yDerivativeMatrixGreen, yDerivativeMatrixBlue );
167+
calculateControlPoints( nCols, nRows, currentSrcRowInt, currentSrcColInt, redMatrix, greenMatrix, blueMatrix, alphaMatrix,
168+
xDerivativeMatrixRed, xDerivativeMatrixGreen, xDerivativeMatrixBlue, xDerivativeMatrixAlpha,
169+
yDerivativeMatrixRed, yDerivativeMatrixGreen, yDerivativeMatrixBlue, yDerivativeMatrixAlpha );
161170
}
162171

163172
//bernstein polynomials
@@ -219,7 +228,24 @@ void QgsCubicRasterResampler::resample( const QImage& srcImage, QImage& dstImage
219228
bp2u * bp3v * cBlue23 +
220229
bp3u * bp3v * cBlue33;
221230

222-
dstImage.setPixel( j, i, qRgb( r, g, b ) );
231+
a = bp0u * bp0v * cAlpha00 +
232+
bp1u * bp0v * cAlpha10 +
233+
bp2u * bp0v * cAlpha20 +
234+
bp3u * bp0v * cAlpha30 +
235+
bp0u * bp1v * cAlpha01 +
236+
bp1u * bp1v * cAlpha11 +
237+
bp2u * bp1v * cAlpha21 +
238+
bp3u * bp1v * cAlpha31 +
239+
bp0u * bp2v * cAlpha02 +
240+
bp1u * bp2v * cAlpha12 +
241+
bp2u * bp2v * cAlpha22 +
242+
bp3u * bp2v * cAlpha32 +
243+
bp0u * bp3v * cAlpha03 +
244+
bp1u * bp3v * cAlpha13 +
245+
bp2u * bp3v * cAlpha23 +
246+
bp3u * bp3v * cAlpha33;
247+
248+
dstImage.setPixel( j, i, qRgba( r, g, b, a ) );
223249
lastSrcColInt = currentSrcColInt;
224250
currentSrcCol += nSrcPerDstX;
225251
}
@@ -295,47 +321,61 @@ void QgsCubicRasterResampler::yDerivativeMatrix( int nCols, int nRows, double* m
295321
}
296322

297323
void QgsCubicRasterResampler::calculateControlPoints( int nCols, int nRows, int currentRow, int currentCol, int* redMatrix, int* greenMatrix, int* blueMatrix,
298-
double* xDerivativeMatrixRed, double* xDerivativeMatrixGreen, double* xDerivativeMatrixBlue,
299-
double* yDerivativeMatrixRed, double* yDerivativeMatrixGreen, double* yDerivativeMatrixBlue )
324+
int* alphaMatrix, double* xDerivativeMatrixRed, double* xDerivativeMatrixGreen, double* xDerivativeMatrixBlue, double* xDerivativeMatrixAlpha,
325+
double* yDerivativeMatrixRed, double* yDerivativeMatrixGreen, double* yDerivativeMatrixBlue, double* yDerivativeMatrixAlpha )
300326
{
301327
int idx00 = currentRow * nCols + currentCol;
302328
int idx10 = idx00 + 1;
303329
int idx01 = idx00 + nCols;
304330
int idx11 = idx01 + 1;
305331

306332
//corner points
307-
cRed00 = redMatrix[idx00]; cGreen00 = greenMatrix[idx00]; cBlue00 = blueMatrix[idx00];
308-
cRed30 = redMatrix[idx10]; cGreen30 = greenMatrix[idx10]; cBlue30 = blueMatrix[idx10];
309-
cRed03 = redMatrix[idx01]; cGreen03 = greenMatrix[idx01]; cBlue03 = blueMatrix[idx01];
310-
cRed33 = redMatrix[idx11]; cGreen33 = greenMatrix[idx11]; cBlue33 = blueMatrix[idx11];
333+
cRed00 = redMatrix[idx00]; cGreen00 = greenMatrix[idx00]; cBlue00 = blueMatrix[idx00]; cAlpha00 = alphaMatrix[idx00];
334+
cRed30 = redMatrix[idx10]; cGreen30 = greenMatrix[idx10]; cBlue30 = blueMatrix[idx10]; cAlpha30 = alphaMatrix[idx10];
335+
cRed03 = redMatrix[idx01]; cGreen03 = greenMatrix[idx01]; cBlue03 = blueMatrix[idx01]; cAlpha03 = alphaMatrix[idx01];
336+
cRed33 = redMatrix[idx11]; cGreen33 = greenMatrix[idx11]; cBlue33 = blueMatrix[idx11]; cAlpha33 = alphaMatrix[idx11];
311337

312338
//control points near c00
313-
cRed10 = cRed00 + 0.333 * xDerivativeMatrixRed[idx00]; cGreen10 = cGreen00 + 0.333 * xDerivativeMatrixGreen[idx00]; cBlue10 = cBlue00 + 0.333 * xDerivativeMatrixBlue[idx00];
314-
cRed01 = cRed00 + 0.333 * yDerivativeMatrixRed[idx00]; cGreen01 = cGreen00 + 0.333 * yDerivativeMatrixGreen[idx00]; cBlue01 = cBlue00 + 0.333 * yDerivativeMatrixBlue[idx00];
315-
cRed11 = cRed10 + 0.333 * yDerivativeMatrixRed[idx00]; cGreen11 = cGreen10 + 0.333 * yDerivativeMatrixGreen[idx00]; cBlue11 = cBlue10 + 0.333 * yDerivativeMatrixBlue[idx00];
339+
cRed10 = cRed00 + 0.333 * xDerivativeMatrixRed[idx00]; cGreen10 = cGreen00 + 0.333 * xDerivativeMatrixGreen[idx00];
340+
cBlue10 = cBlue00 + 0.333 * xDerivativeMatrixBlue[idx00];cAlpha10 = cAlpha00 + 0.333 * xDerivativeMatrixAlpha[idx00];
341+
cRed01 = cRed00 + 0.333 * yDerivativeMatrixRed[idx00]; cGreen01 = cGreen00 + 0.333 * yDerivativeMatrixGreen[idx00];
342+
cBlue01 = cBlue00 + 0.333 * yDerivativeMatrixBlue[idx00];cAlpha01 = cAlpha00 + 0.333 * yDerivativeMatrixAlpha[idx00];
343+
cRed11 = cRed10 + 0.333 * yDerivativeMatrixRed[idx00]; cGreen11 = cGreen10 + 0.333 * yDerivativeMatrixGreen[idx00];
344+
cBlue11 = cBlue10 + 0.333 * yDerivativeMatrixBlue[idx00];cAlpha11 = cAlpha10 + 0.333 * yDerivativeMatrixAlpha[idx00];
316345

317346
//control points near c30
318-
cRed20 = cRed30 - 0.333 * xDerivativeMatrixRed[idx10]; cGreen20 = cGreen30 - 0.333 * xDerivativeMatrixGreen[idx10]; cBlue20 = cBlue30 - 0.333 * xDerivativeMatrixBlue[idx10];
319-
cRed31 = cRed30 + 0.333 * yDerivativeMatrixRed[idx10]; cGreen31 = cGreen30 + 0.333 * yDerivativeMatrixGreen[idx10]; cBlue31 = cBlue30 + 0.333 * yDerivativeMatrixBlue[idx10];
320-
cRed21 = cRed20 + 0.333 * yDerivativeMatrixRed[idx10]; cGreen21 = cGreen20 + 0.333 * yDerivativeMatrixGreen[idx10]; cBlue21 = cBlue20 + 0.333 * yDerivativeMatrixBlue[idx10];
347+
cRed20 = cRed30 - 0.333 * xDerivativeMatrixRed[idx10]; cGreen20 = cGreen30 - 0.333 * xDerivativeMatrixGreen[idx10];
348+
cBlue20 = cBlue30 - 0.333 * xDerivativeMatrixBlue[idx10]; cAlpha20 = cAlpha30 - 0.333 * xDerivativeMatrixAlpha[idx10];
349+
cRed31 = cRed30 + 0.333 * yDerivativeMatrixRed[idx10]; cGreen31 = cGreen30 + 0.333 * yDerivativeMatrixGreen[idx10];
350+
cBlue31 = cBlue30 + 0.333 * yDerivativeMatrixBlue[idx10]; cAlpha31 = cAlpha30 + 0.333 * yDerivativeMatrixAlpha[idx10];
351+
cRed21 = cRed20 + 0.333 * yDerivativeMatrixRed[idx10]; cGreen21 = cGreen20 + 0.333 * yDerivativeMatrixGreen[idx10];
352+
cBlue21 = cBlue20 + 0.333 * yDerivativeMatrixBlue[idx10]; cAlpha21 = cAlpha20 + 0.333 * yDerivativeMatrixAlpha[idx10];
321353

322354
//control points near c03
323-
cRed13 = cRed03 + 0.333 * xDerivativeMatrixRed[idx01]; cGreen13 = cGreen03 + 0.333 * xDerivativeMatrixGreen[idx01]; cBlue13 = cBlue03 + 0.333 * xDerivativeMatrixBlue[idx01];
324-
cRed02 = cRed03 - 0.333 * yDerivativeMatrixRed[idx01]; cGreen02 = cGreen03 - 0.333 * yDerivativeMatrixGreen[idx01]; cBlue02 = cBlue03 - 0.333 * yDerivativeMatrixBlue[idx01];
325-
cRed12 = cRed02 + 0.333 * xDerivativeMatrixRed[idx01]; cGreen12 = cGreen02 + 0.333 * xDerivativeMatrixGreen[idx01]; cBlue12 = cBlue02 + 0.333 * xDerivativeMatrixBlue[idx01];
355+
cRed13 = cRed03 + 0.333 * xDerivativeMatrixRed[idx01]; cGreen13 = cGreen03 + 0.333 * xDerivativeMatrixGreen[idx01];
356+
cBlue13 = cBlue03 + 0.333 * xDerivativeMatrixBlue[idx01]; cAlpha13 = cAlpha03 + 0.333 * xDerivativeMatrixAlpha[idx01];
357+
cRed02 = cRed03 - 0.333 * yDerivativeMatrixRed[idx01]; cGreen02 = cGreen03 - 0.333 * yDerivativeMatrixGreen[idx01];
358+
cBlue02 = cBlue03 - 0.333 * yDerivativeMatrixBlue[idx01]; cAlpha02 = cAlpha03 - 0.333 * yDerivativeMatrixAlpha[idx01];
359+
cRed12 = cRed02 + 0.333 * xDerivativeMatrixRed[idx01]; cGreen12 = cGreen02 + 0.333 * xDerivativeMatrixGreen[idx01];
360+
cBlue12 = cBlue02 + 0.333 * xDerivativeMatrixBlue[idx01]; cAlpha12 = cAlpha02 + 0.333 * xDerivativeMatrixAlpha[idx01];
326361

327362
//control points near c33
328-
cRed23 = cRed33 - 0.333 * xDerivativeMatrixRed[idx11]; cGreen23 = cGreen33 - 0.333 * xDerivativeMatrixGreen[idx11]; cBlue23 = cBlue33 - 0.333 * xDerivativeMatrixBlue[idx11];
329-
cRed32 = cRed33 - 0.333 * yDerivativeMatrixRed[idx11]; cGreen32 = cGreen33 - 0.333 * yDerivativeMatrixGreen[idx11]; cBlue32 = cBlue33 - 0.333 * yDerivativeMatrixBlue[idx11];
330-
cRed22 = cRed32 - 0.333 * xDerivativeMatrixRed[idx11]; cGreen22 = cGreen32 - 0.333 * xDerivativeMatrixGreen[idx11]; cBlue22 = cBlue32 - 0.333 * xDerivativeMatrixBlue[idx11];
363+
cRed23 = cRed33 - 0.333 * xDerivativeMatrixRed[idx11]; cGreen23 = cGreen33 - 0.333 * xDerivativeMatrixGreen[idx11];
364+
cBlue23 = cBlue33 - 0.333 * xDerivativeMatrixBlue[idx11]; cAlpha23 = cAlpha33 - 0.333 * xDerivativeMatrixAlpha[idx11];
365+
cRed32 = cRed33 - 0.333 * yDerivativeMatrixRed[idx11]; cGreen32 = cGreen33 - 0.333 * yDerivativeMatrixGreen[idx11];
366+
cBlue32 = cBlue33 - 0.333 * yDerivativeMatrixBlue[idx11]; cAlpha32 = cAlpha33 - 0.333 * yDerivativeMatrixAlpha[idx11];
367+
cRed22 = cRed32 - 0.333 * xDerivativeMatrixRed[idx11]; cGreen22 = cGreen32 - 0.333 * xDerivativeMatrixGreen[idx11];
368+
cBlue22 = cBlue32 - 0.333 * xDerivativeMatrixBlue[idx11]; cAlpha22 = cAlpha32 - 0.333 * xDerivativeMatrixAlpha[idx11];
331369
}
332370

333-
QRgb QgsCubicRasterResampler::curveInterpolation( QRgb pt1, QRgb pt2, double t, double d1red, double d1green, double d1blue , double d2red, double d2green, double d2blue )
371+
QRgb QgsCubicRasterResampler::curveInterpolation( QRgb pt1, QRgb pt2, double t, double d1red, double d1green, double d1blue, double d1alpha,
372+
double d2red, double d2green, double d2blue, double d2alpha )
334373
{
335374
//control points
336375
double p0r = qRed( pt1 ); double p1r = p0r + 0.333 * d1red; double p3r = qRed( pt2 ); double p2r = p3r - 0.333 * d2red;
337376
double p0g = qGreen( pt1 ); double p1g = p0g + 0.333 * d1green; double p3g = qGreen( pt2 ); double p2g = p3g - 0.333 * d2green;
338377
double p0b = qBlue( pt1 ); double p1b = p0b + 0.333 * d1blue; double p3b = qBlue( pt2 ); double p2b = p3b - 0.333 * d2blue;
378+
double p0a = qAlpha( pt1 ); double p1a = p0a + 0.333 * d1alpha; double p3a = qAlpha( pt2 ); double p2a = p3a - 0.333 * d2alpha;
339379

340380
//bernstein polynomials
341381
double bp0 = calcBernsteinPoly( 3, 0, t );
@@ -346,8 +386,9 @@ QRgb QgsCubicRasterResampler::curveInterpolation( QRgb pt1, QRgb pt2, double t,
346386
int red = bp0 * p0r + bp1 * p1r + bp2 * p2r + bp3 * p3r;
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int green = bp0 * p0g + bp1 * p1g + bp2 * p2g + bp3 * p3g;
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int blue = bp0 * p0b + bp1 * p1b + bp2 * p2b + bp3 * p3b;
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int alpha = bp0 * p0a + bp1 * p1a + bp2 * p2a + bp3 * p3a;
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return qRgb( red, green, blue );
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return qRgba( red, green, blue, alpha );
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}
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double QgsCubicRasterResampler::calcBernsteinPoly( int n, int i, double t )

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