Fix regression with demosaiced DNGs caused by 831a9bb

Demosaiced DNGs (aka LinearRAW PhotometricInterpretation) have 3 samples per pixel, so rawData.getWidth() returns triple the width
Only throw an assert if getWidth is not a multiple of W.  This new implementation assumes that getWidth() will never be zero
when getHeight() is nonzero

Fixes #6996

rtengine/rawimagesource.cc

@@ -744,7 +744,7 @@ void RawImageSource::getWBMults(const ColorTemp &ctemp, const RAWParams &raw, st
 
 void RawImageSource::getImage(const ColorTemp &ctemp, int tran, Imagefloat* image, const PreviewProps &pp, const ToneCurveParams &hrp, const RAWParams &raw)
 {
-    assert(rawData.getHeight() == H && rawData.getWidth() == W);
+    assert(rawData.getHeight() == H && !(rawData.getWidth() % W));
 
     MyMutex::MyLock lock(getImageMutex);
 
@@ -1747,7 +1747,7 @@ void RawImageSource::preprocess(const RAWParams &raw, const LensProfParams &lens
 
 void RawImageSource::demosaic(const RAWParams &raw, bool autoContrast, double &contrastThreshold, bool cache)
 {
-    assert(rawData.getHeight() == H && rawData.getWidth() == W);
+    assert(rawData.getHeight() == H && !(rawData.getWidth() % W));
 
     MyTime t1, t2;
     t1.set();
@@ -3842,7 +3842,7 @@ void RawImageSource::hlRecovery(const std::string &method, float* red, float* gr
 
 void RawImageSource::getAutoExpHistogram(LUTu & histogram, int& histcompr)
 {
-    assert(rawData.getHeight() == H && rawData.getWidth() == W);
+    assert(rawData.getHeight() == H && !(rawData.getWidth() % W));
 
 //    BENCHFUN
     histcompr = 3;
@@ -7487,7 +7487,7 @@ void RawImageSource::getrgbloc(int begx, int begy, int yEn, int xEn, int cx, int
 
 void RawImageSource::getAutoWBMultipliersitc(bool extra, double & tempref, double & greenref, double & tempitc, double & greenitc, float &temp0, float &delta,  int &bia, int &dread, int &kcam, int &nocam, float &studgood, float &minchrom, int &kmin,  float &minhist, float &maxhist, int begx, int begy, int yEn, int xEn, int cx, int cy, int bf_h, int bf_w, double & rm, double & gm, double & bm, const WBParams & wbpar, const ColorManagementParams & cmp, const RAWParams & raw, const ToneCurveParams &hrp)
 {
-    assert(rawData.getHeight() == H && rawData.getWidth() == W);
+    assert(rawData.getHeight() == H && !(rawData.getWidth() % W));
 
 //    BENCHFUN
     constexpr double clipHigh = 64000.0;
@@ -7713,7 +7713,7 @@ void RawImageSource::getAutoWBMultipliersitc(bool extra, double & tempref, doubl
 
 void RawImageSource::getAutoWBMultipliers(double &rm, double &gm, double &bm)
 {
-    assert(rawData.getHeight() == H && rawData.getWidth() == W);
+    assert(rawData.getHeight() == H && !(rawData.getWidth() % W));
 
 //    BENCHFUN
     constexpr double clipHigh = 64000.0;
@@ -7931,7 +7931,7 @@ void RawImageSource::getAutoWBMultipliers(double &rm, double &gm, double &bm)
 
 ColorTemp RawImageSource::getSpotWB(std::vector<Coord2D> &red, std::vector<Coord2D> &green, std::vector<Coord2D> &blue, int tran, double equal, StandardObserver observer)
 {
-    assert(rawData.getHeight() == H && rawData.getWidth() == W);
+    assert(rawData.getHeight() == H && !(rawData.getWidth() % W));
 
     int x;
     int y;
@@ -8319,7 +8319,7 @@ bool RawImageSource::isGainMapSupported() const
 
 void RawImageSource::applyDngGainMap(const float black[4], const std::vector<GainMap> &gainMaps)
 {
-    assert(rawData.getHeight() == H && rawData.getWidth() == W);
+    assert(rawData.getHeight() == H && !(rawData.getWidth() % W));
 
     // now we can apply each gain map to raw_data
     array2D<float> mvals[2][2];