Working towards proper color correction

src/lib/cimb_translator/CimbReader.cpp

@@ -144,6 +144,30 @@ bool CimbReader::done() const
 	return !_good or _positions.done();
 }
 
+void CimbReader::init_ccm()
+{
+	// if no fountain header, we use a simplified von kries matrix?
+	// or maybe don't bother? Might be easier if we treat it as authoritative (but old),
+	// rather than having a "good" CCM saved sometimes, but not always.
+	if (_fountainColorHeader.id() == 0) // & decoder CCM isn't set?
+	{
+		//updateColorCorrection(_image, decoder);
+		return;
+	}
+
+	// should most of this logic go into CimbDecoder?
+
+	// full ccm, using header values as known color index
+	// 1. get positions
+	// 2. put fountain header into a bitbuffer so we can read decoder.color_bits() bits at a time
+	// 3. using expected fountain headers, decode color for each position
+	// 4. sample corners
+	// 5. group results from #3 and #4 by expected color index, compute avgs
+	// 6. generate ccm from avgs in #5
+	// 7. save ccm in decoder. Success! We hope
+
+}
+
 void CimbReader::update_metadata(char* buff, unsigned len)
 {
 	if (len == 0 and _fountainColorHeader.id() == 0)

src/lib/cimb_translator/CimbReader.h

@@ -19,6 +19,7 @@ class CimbReader
 	unsigned read_color(const PositionData& pos);
 	bool done() const;
 
+	void init_ccm();
 	void update_metadata(char* buff, unsigned len);
 
 	unsigned num_reads() const;

src/lib/encoder/Decoder.h

@@ -95,12 +95,11 @@ inline unsigned Decoder::do_decode(CimbReader& reader, STREAM& ostream)
 		// flush symbols
 		reed_solomon_stream rss(ostream, _eccBytes, _eccBlockSize);
 		symbolBits.flush(rss);
-
-		// TODO: get fountain headers out of ostream somehow.
-		// after we call symbolBits.flush(), the underlying aligned stream (ostream) may have knowledge about
-		// the fountain headers -- one per chunk (see chunk_size()) -- which we can use to help us with the color decode...
 	}
 
+	// do color correction init, now that we (hopefully) have some fountain headers from the symbol decode
+	reader.init_ccm();
+
 	bitbuffer colorBits(cimbar::Config::capacity(_colorBits));
 	// then decode colors.
 	for (const PositionData& p : colorPositions)

src/lib/fountain/FountainMetadata.h

@@ -47,7 +47,7 @@ class FountainMetadata
 
 	uint32_t id() const
 	{
-		uint32_t shortid;
+		uint32_t shortid = 0;
 		std::copy(data(), data()+4, reinterpret_cast<uint8_t*>(&shortid));
 		return shortid;
 	}