DngDecoder/RawImageDataFloat::scaleBlackWhite(): no white level means 1.0F

`RawImageDataFloat::scaleBlackWhite()` is dead code,
i bet nobody uses it.

Author: LebedevRI

src/librawspeed/common/RawImageDataFloat.cpp

@@ -122,8 +122,8 @@ void RawImageDataFloat::scaleBlackWhite() {
 
   const int skipBorder = 150;
   int gw = (dim.x - skipBorder) * cpp;
-  if ((blackAreas.empty() && !blackLevelSeparate && blackLevel < 0) ||
-      !whitePoint) { // Estimate
+  // NOTE: lack of whitePoint means that it is pre-normalized.
+  if (blackAreas.empty() && !blackLevelSeparate && blackLevel < 0) { // Estimate
     float b = 100000000;
     float m = -10000000;
     for (int row = skipBorder * cpp; row < (dim.y - skipBorder); row++) {
@@ -135,10 +135,7 @@ void RawImageDataFloat::scaleBlackWhite() {
     }
     if (blackLevel < 0)
       blackLevel = static_cast<int>(b);
-    if (!whitePoint)
-      whitePoint = static_cast<int>(m);
-    writeLog(DEBUG_PRIO::INFO, "Estimated black:%d, Estimated white: %d",
-             blackLevel, *whitePoint);
+    writeLog(DEBUG_PRIO::INFO, "Estimated black:%d", blackLevel);
   }
 
   /* If filter has not set separate blacklevel, compute or fetch it */
@@ -161,8 +158,8 @@ void RawImageDataFloat::scaleValues(int start_y, int end_y) {
       v ^= 1;
     if ((mOffset.y & 1) != 0)
       v ^= 2;
-    mul[i] =
-        65535.0F / static_cast<float>(*whitePoint - blackLevelSeparate1D(v));
+    mul[i] = 65535.0F / static_cast<float>(whitePoint.value_or(1.0F) -
+                                           blackLevelSeparate1D(v));
     sub[i] = static_cast<float>(blackLevelSeparate1D(v));
   }
   for (int y = start_y; y < end_y; y++) {

src/librawspeed/decoders/DngDecoder.cpp

@@ -602,9 +602,9 @@ void DngDecoder::handleMetadata(const TiffIFD* raw) {
     // Default white level is (2 ** BitsPerSample) - 1
     mRaw->whitePoint = implicit_cast<int>((1UL << bps) - 1UL);
   } else if (mRaw->getDataType() == RawImageType::F32) {
-    // Default white level is 1.0f. But we can't represent that here.
-    // Fall back to uninitialized value instead.
-    mRaw->whitePoint = 65536;
+    // Default white level is 1.0f. But we can't represent that here,
+    // so just claim that we don't know it, and users shall default to 1.0F.
+    mRaw->whitePoint.reset();
   }
 
   if (raw->hasEntry(TiffTag::WHITELEVEL)) {