19 files changed, 687 insertions, 131 deletions
diff --git a/.hgignore b/.hgignore
index 403b73df6d..94391e11ab 100644
--- a/.hgignore
+++ b/.hgignore
@@ -1,5 +1,6 @@
 syntax: glob
 
+
 # WinMerge temp files
 *.bak
 # Compiled python bytecode
diff --git a/indra/integration_tests/llimage_libtest/llimage_libtest.cpp b/indra/integration_tests/llimage_libtest/llimage_libtest.cpp
index 48e876429d..36c5b67826 100644
--- a/indra/integration_tests/llimage_libtest/llimage_libtest.cpp
+++ b/indra/integration_tests/llimage_libtest/llimage_libtest.cpp
@@ -54,6 +54,11 @@ static const char USAGE[] = "\n"
 " -o, --output <file1 .. file2> OR <type>\n"
 "        List of image files to create (assumes same order as for input files)\n"
 "        OR 3 letters file type extension to convert each input file into.\n"
+" -load, --load_size <n>\n"
+"        Portion of the input file to load, in bytes."
+"        If (load == 0), it will load the whole file."
+"        If (load == -1), it will load the size relevant to reach the requested discard level (see -d)."
+"        Only valid for j2c images. Default is 0 (load whole file).\n"
 " -r, --region <x0, y0, x1, y1>\n"
 "        Crop region applied to the input files in pixels.\n"
 "        Only used for j2c images. Default is no region cropping.\n"
@@ -104,22 +109,52 @@ void output_image_stats(LLPointer<LLImageFormatted> image, const std::string &fi
 	// Print out some statistical data on the image
 	std::cout << "Image stats for : " << filename << ", extension : " << image->getExtension() << std::endl;
 
-	std::cout << "    with : " << (int)(image->getWidth())       << ", height : " << (int)(image->getHeight())       << std::endl;
-	std::cout << "    comp : " << (int)(image->getComponents())  << ", levels : " << (int)(image->getDiscardLevel()) << std::endl;
-	std::cout << "    head : " << (int)(image->calcHeaderSize()) << ",   data : " << (int)(image->getDataSize())     << std::endl;
+	std::cout << "    with : " << (int)(image->getWidth())       << ", height : " << (int)(image->getHeight())   << std::endl;
+	std::cout << "    comp : " << (int)(image->getComponents())  << ", levels : " << (int)(image->getLevels())   << std::endl;
+	std::cout << "    head : " << (int)(image->calcHeaderSize()) << ",   data : " << (int)(image->getDataSize()) << std::endl;
 
 	return;
 }
 
 // Load an image from file and return a raw (decompressed) instance of its data
-LLPointer<LLImageRaw> load_image(const std::string &src_filename, int discard_level, int* region, bool output_stats)
+LLPointer<LLImageRaw> load_image(const std::string &src_filename, int discard_level, int* region, int load_size, bool output_stats)
 {
 	LLPointer<LLImageFormatted> image = create_image(src_filename);
 	
-	// This just loads the image file stream into a buffer. No decoding done.
-	if (!image->load(src_filename))
+	// We support partial loading only for j2c images
+	if (image->getCodec() == IMG_CODEC_J2C)
 	{
-		return NULL;
+		// Load the header
+		if (!image->load(src_filename, 600))
+		{
+			return NULL;
+		}
+		S32 h = ((LLImageJ2C*)(image.get()))->calcHeaderSize();
+		S32 d = (load_size > 0 ? ((LLImageJ2C*)(image.get()))->calcDiscardLevelBytes(load_size) : 0);
+		S8  r = ((LLImageJ2C*)(image.get()))->getRawDiscardLevel();
+		std::cout << "Merov debug : header = " << h << ", load_size = " << load_size << ", discard level = " << d << ", raw discard level = " << r << std::endl;
+		for (d = 0; d < MAX_DISCARD_LEVEL; d++)
+		{
+			S32 data_size = ((LLImageJ2C*)(image.get()))->calcDataSize(d);
+			std::cout << "Merov debug : discard_level = " << d << ", data_size = " << data_size << std::endl;
+		}
+		if (load_size < 0)
+		{
+			load_size = (discard_level != -1 ? ((LLImageJ2C*)(image.get()))->calcDataSize(discard_level) : 0);
+		}
+		// Load the requested byte range
+		if (!image->load(src_filename, load_size))
+		{
+			return NULL;
+		}
+	}
+	else 
+	{
+		// This just loads the image file stream into a buffer. No decoding done.
+		if (!image->load(src_filename))
+		{
+			return NULL;
+		}
 	}
 	
 	if(	(image->getComponents() != 3) && (image->getComponents() != 4) )
@@ -310,6 +345,7 @@ int main(int argc, char** argv)
 	bool image_stats = false;
 	int* region = NULL;
 	int discard_level = -1;
+	int load_size = 0;
 	int precincts_size = -1;
 	int blocks_size = -1;
 	int levels = 0;
@@ -396,6 +432,22 @@ int main(int argc, char** argv)
 				discard_level = llclamp(discard_level,0,5);
 			}
 		}
+		else if (!strcmp(argv[arg], "--load_size") || !strcmp(argv[arg], "-load"))
+		{
+			std::string value_str;
+			if ((arg + 1) < argc)
+			{
+				value_str = argv[arg+1];
+			}
+			if (((arg + 1) >= argc) || (value_str[0] == '-'))
+			{
+				std::cout << "No valid --load_size argument given, load_size ignored" << std::endl;
+			}
+			else
+			{
+				load_size = atoi(value_str.c_str());
+			}
+		}
 		else if (!strcmp(argv[arg], "--precincts") || !strcmp(argv[arg], "-p"))
 		{
 			std::string value_str;
@@ -510,7 +562,7 @@ int main(int argc, char** argv)
 	for (; in_file != in_end; ++in_file, ++out_file)
 	{
 		// Load file
-		LLPointer<LLImageRaw> raw_image = load_image(*in_file, discard_level, region, image_stats);
+		LLPointer<LLImageRaw> raw_image = load_image(*in_file, discard_level, region, load_size, image_stats);
 		if (!raw_image)
 		{
 			std::cout << "Error: Image " << *in_file << " could not be loaded" << std::endl;
diff --git a/indra/llimage/llimage.cpp b/indra/llimage/llimage.cpp
index 56e01ac851..7f95441075 100644
--- a/indra/llimage/llimage.cpp
+++ b/indra/llimage/llimage.cpp
@@ -48,11 +48,13 @@
 //static
 std::string LLImage::sLastErrorMessage;
 LLMutex* LLImage::sMutex = NULL;
+bool LLImage::sUseNewByteRange = false;
 LLPrivateMemoryPool* LLImageBase::sPrivatePoolp = NULL ;
 
 //static
-void LLImage::initClass()
+void LLImage::initClass(bool use_new_byte_range)
 {
+	sUseNewByteRange = use_new_byte_range;
 	sMutex = new LLMutex(NULL);
 
 	LLImageBase::createPrivatePool() ;
@@ -1334,7 +1336,8 @@ LLImageFormatted::LLImageFormatted(S8 codec)
 	  mCodec(codec),
 	  mDecoding(0),
 	  mDecoded(0),
-	  mDiscardLevel(-1)
+	  mDiscardLevel(-1),
+	  mLevels(0)
 {
 	mMemType = LLMemType::MTYPE_IMAGEFORMATTED;
 }
@@ -1561,7 +1564,7 @@ void LLImageFormatted::appendData(U8 *data, S32 size)
 
 //----------------------------------------------------------------------------
 
-BOOL LLImageFormatted::load(const std::string &filename)
+BOOL LLImageFormatted::load(const std::string &filename, int load_size)
 {
 	resetLastError();
 
@@ -1580,14 +1583,19 @@ BOOL LLImageFormatted::load(const std::string &filename)
 		return FALSE;
 	}
 
+	// Constrain the load size to acceptable values
+	if ((load_size == 0) || (load_size > file_size))
+	{
+		load_size = file_size;
+	}
 	BOOL res;
-	U8 *data = allocateData(file_size);
-	apr_size_t bytes_read = file_size;
+	U8 *data = allocateData(load_size);
+	apr_size_t bytes_read = load_size;
 	apr_status_t s = apr_file_read(apr_file, data, &bytes_read); // modifies bytes_read
-	if (s != APR_SUCCESS || (S32) bytes_read != file_size)
+	if (s != APR_SUCCESS || (S32) bytes_read != load_size)
 	{
 		deleteData();
-		setLastError("Unable to read entire file",filename);
+		setLastError("Unable to read file",filename);
 		res = FALSE;
 	}
 	else
diff --git a/indra/llimage/llimage.h b/indra/llimage/llimage.h
index 4469c9e860..a643e4d9f5 100644
--- a/indra/llimage/llimage.h
+++ b/indra/llimage/llimage.h
@@ -48,6 +48,8 @@ const S32 MAX_PRECINCT_SIZE = 2048;			// No reason to be bigger than MAX_IMAGE_S
 const S32 MIN_PRECINCT_SIZE = 4;			// Can't be smaller than MIN_BLOCK_SIZE
 const S32 MAX_BLOCK_SIZE = 64;				// Max total block size is 4096, hence 64x64 when using square blocks
 const S32 MIN_BLOCK_SIZE = 4;				// Min block dim is 4 according to jpeg2000 spec
+const S32 MIN_LAYER_SIZE = 2000;			// Size of the first quality layer (after header). Must be > to FIRST_PACKET_SIZE!!
+const S32 MAX_NB_LAYERS = 64;				// Max number of layers we'll entertain in SL (practical limit)
 
 const S32 MIN_IMAGE_SIZE = (1<<MIN_IMAGE_MIP); // 4, only used for expand/contract power of 2
 const S32 MAX_IMAGE_SIZE = (1<<MAX_IMAGE_MIP); // 2048
@@ -60,6 +62,7 @@ const S32 MAX_IMAGE_DATA_SIZE = MAX_IMAGE_AREA * MAX_IMAGE_COMPONENTS; //2048 *
 // *TODO: change both to 1024 when SIM texture fetching is deprecated
 const S32 FIRST_PACKET_SIZE = 600;
 const S32 MAX_IMG_PACKET_SIZE = 1000;
+const S32 HTTP_PACKET_SIZE = 1496;
 
 // Base classes for images.
 // There are two major parts for the image:
@@ -89,15 +92,18 @@ typedef enum e_image_codec
 class LLImage
 {
 public:
-	static void initClass();
+	static void initClass(bool use_new_byte_range = false);
 	static void cleanupClass();
 
 	static const std::string& getLastError();
 	static void setLastError(const std::string& message);
 	
+	static bool useNewByteRange() { return sUseNewByteRange; }
+	
 protected:
 	static LLMutex* sMutex;
 	static std::string sLastErrorMessage;
+	static bool sUseNewByteRange;
 };
 
 //============================================================================
@@ -294,7 +300,7 @@ public:
 	// getRawDiscardLevel() by default returns mDiscardLevel, but may be overridden (LLImageJ2C)
 	virtual S8  getRawDiscardLevel() { return mDiscardLevel; }
 	
-	BOOL load(const std::string& filename);
+	BOOL load(const std::string& filename, int load_size = 0);
 	BOOL save(const std::string& filename);
 
 	virtual BOOL updateData() = 0; // pure virtual
@@ -313,6 +319,8 @@ public:
 	BOOL isDecoded()  const { return mDecoded ? TRUE : FALSE; }
 	void setDiscardLevel(S8 discard_level) { mDiscardLevel = discard_level; }
 	S8 getDiscardLevel() const { return mDiscardLevel; }
+	S8 getLevels() const { return mLevels; }
+	void setLevels(S8 nlevels) { mLevels = nlevels; }
 
 	// setLastError needs to be deferred for J2C images since it may be called from a DLL
 	virtual void resetLastError();
@@ -325,7 +333,8 @@ protected:
 	S8 mCodec;
 	S8 mDecoding;
 	S8 mDecoded;  // unused, but changing LLImage layout requires recompiling static Mac/Linux libs. 2009-01-30 JC
-	S8 mDiscardLevel;
+	S8 mDiscardLevel;	// Current resolution level worked on. 0 = full res, 1 = half res, 2 = quarter res, etc...
+	S8 mLevels;			// Number of resolution levels in that image. Min is 1. 0 means unknown.
 	
 public:
 	static S32 sGlobalFormattedMemory;
diff --git a/indra/llimage/llimagej2c.cpp b/indra/llimage/llimagej2c.cpp
index cc8cb66d73..69d261c9a6 100644
--- a/indra/llimage/llimagej2c.cpp
+++ b/indra/llimage/llimagej2c.cpp
@@ -56,7 +56,7 @@ std::string LLImageJ2C::getEngineInfo()
 LLImageJ2C::LLImageJ2C() : 	LLImageFormatted(IMG_CODEC_J2C),
 							mMaxBytes(0),
 							mRawDiscardLevel(-1),
-							mRate(0.0f),
+							mRate(DEFAULT_COMPRESSION_RATE),
 							mReversible(FALSE),
 							mAreaUsedForDataSizeCalcs(0)
 {
@@ -142,6 +142,7 @@ BOOL LLImageJ2C::updateData()
 
 BOOL LLImageJ2C::initDecode(LLImageRaw &raw_image, int discard_level, int* region)
 {
+	setDiscardLevel(discard_level != -1 ? discard_level : 0);
 	return mImpl->initDecode(*this,raw_image,discard_level,region);
 }
 
@@ -261,19 +262,35 @@ S32 LLImageJ2C::calcHeaderSizeJ2C()
 //static
 S32 LLImageJ2C::calcDataSizeJ2C(S32 w, S32 h, S32 comp, S32 discard_level, F32 rate)
 {
-	// Note: this only provides an *estimate* of the size in bytes of an image level
-	// *TODO: find a way to read the true size (when available) and convey the fact
-	// that the result is an estimate in the other cases
-	if (rate <= 0.f) rate = .125f;
-	while (discard_level > 0)
+	// Note: This provides an estimation for the first to last quality layer of a given discard level
+	// This is however an efficient approximation, as the true discard level boundary would be
+	// in general too big for fast fetching.
+	// For details about the equation used here, see https://wiki.lindenlab.com/wiki/THX1138_KDU_Improvements#Byte_Range_Study
+
+	// Estimate the number of layers. This is consistent with what's done for j2c encoding in LLImageJ2CKDU::encodeImpl().
+	S32 nb_layers = 1;
+	S32 surface = w*h;
+	S32 s = 64*64;
+	while (surface > s)
 	{
-		if (w < 1 || h < 1)
-			break;
-		w >>= 1;
-		h >>= 1;
-		discard_level--;
+		nb_layers++;
+		s *= 4;
 	}
-	S32 bytes = (S32)((F32)(w*h*comp)*rate);
+	F32 layer_factor =  3.0f * (7 - llclamp(nb_layers,1,6));
+	
+	// Compute w/pow(2,discard_level) and h/pow(2,discard_level)
+	w >>= discard_level;
+	h >>= discard_level;
+	w = llmax(w, 1);
+	h = llmax(h, 1);
+
+	// Temporary: compute both new and old range and pick one according to the settings TextureNewByteRange 
+	// *TODO: Take the old code out once we have enough tests done
+	S32 bytes;
+	S32 new_bytes = sqrt((F32)(w*h))*(F32)(comp)*rate*1000.f/layer_factor;
+	S32 old_bytes = (S32)((F32)(w*h*comp)*rate);
+	//llinfos << "Merov debug : w = " << w << ", h = " << h << ", c = " << comp << ", r = " << rate << ", d = " << discard_level << ", l = " << nb_layers << ", old = " << old_bytes << ", new = " << new_bytes << llendl;
+	bytes = (LLImage::useNewByteRange() ? new_bytes : old_bytes);
 	bytes = llmax(bytes, calcHeaderSizeJ2C());
 	return bytes;
 }
@@ -283,15 +300,12 @@ S32 LLImageJ2C::calcHeaderSize()
 	return calcHeaderSizeJ2C();
 }
 
-
-// calcDataSize() returns how many bytes to read 
-// to load discard_level (including header and higher discard levels)
+// calcDataSize() returns how many bytes to read to load discard_level (including header)
 S32 LLImageJ2C::calcDataSize(S32 discard_level)
 {
 	discard_level = llclamp(discard_level, 0, MAX_DISCARD_LEVEL);
-
 	if ( mAreaUsedForDataSizeCalcs != (getHeight() * getWidth()) 
-		|| mDataSizes[0] == 0)
+		|| (mDataSizes[0] == 0))
 	{
 		mAreaUsedForDataSizeCalcs = getHeight() * getWidth();
 		
@@ -301,25 +315,6 @@ S32 LLImageJ2C::calcDataSize(S32 discard_level)
 			mDataSizes[level] = calcDataSizeJ2C(getWidth(), getHeight(), getComponents(), level, mRate);
 			level--;
 		}
-
-		/* This is technically a more correct way to calculate the size required
-		   for each discard level, since they should include the size needed for
-		   lower levels.   Unfortunately, this doesn't work well and will lead to 
-		   download stalls.  The true correct way is to parse the header.  This will
-		   all go away with http textures at some point.
-
-		// Calculate the size for each discard level.   Lower levels (higher quality)
-		// contain the cumulative size of higher levels		
-		S32 total_size = calcHeaderSizeJ2C();
-
-		S32 level = MAX_DISCARD_LEVEL;	// Start at the highest discard
-		while ( level >= 0 )
-		{	// Add in this discard level and all before it
-			total_size += calcDataSizeJ2C(getWidth(), getHeight(), getComponents(), level, mRate);
-			mDataSizes[level] = total_size;
-			level--;
-		}
-		*/
 	}
 	return mDataSizes[discard_level];
 }
@@ -348,11 +343,6 @@ S32 LLImageJ2C::calcDiscardLevelBytes(S32 bytes)
 	return discard_level;
 }
 
-void LLImageJ2C::setRate(F32 rate)
-{
-	mRate = rate;
-}
-
 void LLImageJ2C::setMaxBytes(S32 max_bytes)
 {
 	mMaxBytes = max_bytes;
diff --git a/indra/llimage/llimagej2c.h b/indra/llimage/llimagej2c.h
index 914174fc57..91c344d12f 100644
--- a/indra/llimage/llimagej2c.h
+++ b/indra/llimage/llimagej2c.h
@@ -31,6 +31,9 @@
 #include "llassettype.h"
 #include "llmetricperformancetester.h"
 
+// JPEG2000 : compression rate used in j2c conversion.
+const F32 DEFAULT_COMPRESSION_RATE = 1.f/8.f;
+
 class LLImageJ2CImpl;
 class LLImageCompressionTester ;
 
@@ -67,12 +70,11 @@ public:
 
 	// Encode accessors
 	void setReversible(const BOOL reversible); // Use non-lossy?
-	void setRate(F32 rate);
 	void setMaxBytes(S32 max_bytes);
 	S32 getMaxBytes() const { return mMaxBytes; }
 
 	static S32 calcHeaderSizeJ2C();
-	static S32 calcDataSizeJ2C(S32 w, S32 h, S32 comp, S32 discard_level, F32 rate = 0.f);
+	static S32 calcDataSizeJ2C(S32 w, S32 h, S32 comp, S32 discard_level, F32 rate = DEFAULT_COMPRESSION_RATE);
 
 	static std::string getEngineInfo();
 
diff --git a/indra/llkdu/llimagej2ckdu.cpp b/indra/llkdu/llimagej2ckdu.cpp
index c156ed0cef..cbfc34ebb8 100644
--- a/indra/llkdu/llimagej2ckdu.cpp
+++ b/indra/llkdu/llimagej2ckdu.cpp
@@ -32,6 +32,7 @@
 #include "llmath.h"
 #include "llkdumem.h"
 
+#include "kdu_block_coding.h"
 
 class kdc_flow_control {
 	
@@ -244,7 +245,9 @@ void LLImageJ2CKDU::setupCodeStream(LLImageJ2C &base, BOOL keep_codestream, ECod
 	mCodeStreamp->create(mInputp);
 
 	// Set the maximum number of bytes to use from the codestream
-	mCodeStreamp->set_max_bytes(max_bytes);
+	// *TODO: This seems to be wrong. The base class should have no idea of how j2c compression works so no
+	// good way of computing what's the byte range to be used.
+	mCodeStreamp->set_max_bytes(max_bytes,true);
 
 	//	If you want to flip or rotate the image for some reason, change
 	// the resolution, or identify a restricted region of interest, this is
@@ -291,8 +294,13 @@ void LLImageJ2CKDU::setupCodeStream(LLImageJ2C &base, BOOL keep_codestream, ECod
 		}
 	}
 
+	// Get the number of resolution levels in that image
+	mLevels = mCodeStreamp->get_min_dwt_levels();
+	
+	// Set the base dimensions
 	base.setSize(dims.size.x, dims.size.y, components);
-
+	base.setLevels(mLevels);
+	
 	if (!keep_codestream)
 	{
 		mCodeStreamp->destroy();
@@ -351,7 +359,8 @@ BOOL LLImageJ2CKDU::initEncode(LLImageJ2C &base, LLImageRaw &raw_image, int bloc
 	mLevels = levels;
 	if (mLevels != 0)
 	{
-		mLevels = llclamp(mLevels,MIN_DECOMPOSITION_LEVELS,MIN_DECOMPOSITION_LEVELS);		
+		mLevels = llclamp(mLevels,MIN_DECOMPOSITION_LEVELS,MAX_DECOMPOSITION_LEVELS);
+		base.setLevels(mLevels);
 	}
 	return TRUE;
 }
@@ -364,6 +373,9 @@ BOOL LLImageJ2CKDU::initDecode(LLImageJ2C &base, LLImageRaw &raw_image, F32 deco
 	// To regain control, we throw an exception, and catch it here.
 	try
 	{
+		// Merov : Test!! DO NOT COMMIT!!
+		//findDiscardLevelsBoundaries(base);
+
 		base.updateRawDiscardLevel();
 		setupCodeStream(base, TRUE, mode);
 
@@ -381,7 +393,7 @@ BOOL LLImageJ2CKDU::initDecode(LLImageJ2C &base, LLImageRaw &raw_image, F32 deco
 			region_kdu->size.y = region[3] - region[1];
 		}
 		int discard = (discard_level != -1 ? discard_level : base.getRawDiscardLevel());
-		
+		//llinfos << "Merov debug : initDecode, discard used = " << discard << ", asked = " << discard_level << llendl;
 		// Apply loading restrictions
 		mCodeStreamp->apply_input_restrictions( first_channel, max_channel_count, discard, 0, region_kdu);
 		
@@ -394,12 +406,9 @@ BOOL LLImageJ2CKDU::initDecode(LLImageJ2C &base, LLImageRaw &raw_image, F32 deco
 
 		// Resize raw_image according to the image to be decoded
 		kdu_dims dims; mCodeStreamp->get_dims(0,dims);
-		// *TODO: Use the real number of levels read from the file throughout the code instead of relying on an infered value from dimensions
-		//S32 levels = mCodeStreamp->get_min_dwt_levels();
 		S32 channels = base.getComponents() - first_channel;
 		channels = llmin(channels,max_channel_count);
 		raw_image.resize(dims.size.x, dims.size.y, channels);
-		//llinfos << "j2c image dimension: width = " << dims.size.x << ", height = " << dims.size.y << ", channels = " << channels << ", levels = " << levels << llendl;
 
 		if (!mTileIndicesp)
 		{
@@ -583,12 +592,6 @@ BOOL LLImageJ2CKDU::encodeImpl(LLImageJ2C &base, const LLImageRaw &raw_image, co
 			comment.put_text(comment_text);
 		}
 
-		// Set codestream options
-		int num_layer_specs = 0;
-
-		kdu_long layer_bytes[64];
-		U32 max_bytes = 0;
-
 		if (num_components >= 3)
 		{
 			// Note that we always use YCC and not YUV
@@ -596,67 +599,63 @@ BOOL LLImageJ2CKDU::encodeImpl(LLImageJ2C &base, const LLImageRaw &raw_image, co
 			set_default_colour_weights(codestream.access_siz());
 		}
 
+		// Set codestream options
+		int nb_layers = 0;
+		kdu_long layer_bytes[MAX_NB_LAYERS];
+		U32 max_bytes = (U32)(base.getWidth() * base.getHeight() * base.getComponents());
+
+		// Rate is the argument passed into the LLImageJ2C which specifies the target compression rate. The default is 8:1.
+		// *TODO: mRate is actually always 8:1 in the viewer. Test different values.
+		llassert (base.mRate > 0.f);
+		max_bytes = (U32)((F32)(max_bytes) * base.mRate);
+		
+		// If the image is very small, code it in a lossless way.
+		// Note: it'll also have only 1 layer which is fine as there's no point reordering blocks in that case.
+		if (max_bytes < FIRST_PACKET_SIZE)
+		{
+			reversible = true;
+		}
+		
+		// This code is where we specify the target number of bytes for each quality layer.
+		// We're using a logarithmic spacing rule that fits with our way of fetching texture data.
+		// Note: For more info on this layers business, read kdu_codestream::flush() doc in kdu_compressed.h
+		U32 i = FIRST_PACKET_SIZE;
+		while ((i < max_bytes) && (nb_layers < (MAX_NB_LAYERS-1)))
+		{
+			if (i == FIRST_PACKET_SIZE * 4)
+			{
+				// That really just means that the first layer is FIRST_PACKET_SIZE and the second is MIN_LAYER_SIZE
+				i = MIN_LAYER_SIZE;
+			}
+			layer_bytes[nb_layers] = i;
+			nb_layers++;
+			i *= 4;
+		}
+
 		if (reversible)
 		{
 			codestream.access_siz()->parse_string("Creversible=yes");
-			// *TODO: we should use yuv in reversible mode and one level since those images are small. 
+			// *TODO: we should use yuv in reversible mode and one res level since those images are small. 
 			// Don't turn this on now though as both create problems on decoding for the moment
 			//codestream.access_siz()->parse_string("Clevels=1");
 			//codestream.access_siz()->parse_string("Cycc=no");
-			// If we're doing reversible (i.e. lossless compression), assumes we're not using quality layers.
-			// *TODO: this is incorrect and unecessary. Try using the regular layer setting.
-			codestream.access_siz()->parse_string("Clayers=1");
-			num_layer_specs = 1;
-			layer_bytes[0] = 0;
+			// In the reversible case, set the last entry of that table to 0 so that all generated bits will
+			// indeed be output by the time the last quality layer is encountered.
+			layer_bytes[nb_layers] = 0;
 		}
 		else
 		{
-			// Rate is the argument passed into the LLImageJ2C which
-			// specifies the target compression rate.  The default is 8:1.
-			// Possibly if max_bytes < 500, we should just use the default setting?
-			// *TODO: mRate is actually always 8:1 in the viewer. Test different values. Also force to reversible for small (< 500 bytes) textures.
-			if (base.mRate != 0.f)
-			{
-				max_bytes = (U32)(base.mRate*base.getWidth()*base.getHeight()*base.getComponents());
-			}
-			else
-			{
-				max_bytes = (U32)(base.getWidth()*base.getHeight()*base.getComponents()*0.125);
-			}
-
-			const U32 min_bytes = FIRST_PACKET_SIZE;
-			if (max_bytes > min_bytes)
-			{
-				U32 i;
-				// This code is where we specify the target number of bytes for
-				// each layer.  Not sure if we should do this for small images
-				// or not.  The goal is to have this roughly align with
-				// different quality levels that we decode at.
-				for (i = min_bytes; i < max_bytes; i*=4)
-				{
-					if (i == min_bytes * 4)
-					{
-						i = 2000;
-					}
-					layer_bytes[num_layer_specs] = i;
-					num_layer_specs++;
-				}
-				layer_bytes[num_layer_specs] = max_bytes;
-				num_layer_specs++;
-
-				std::string layer_string = llformat("Clayers=%d",num_layer_specs);
-				codestream.access_siz()->parse_string(layer_string.c_str());
-			}
-			else
-			{
-				layer_bytes[0] = min_bytes;
-				num_layer_specs = 1;
-				std::string layer_string = llformat("Clayers=%d",num_layer_specs);
-				codestream.access_siz()->parse_string(layer_string.c_str());
-			}
+			// Truncate the last quality layer if necessary so to fit the set compression ratio
+			layer_bytes[nb_layers] = max_bytes;
 		}
+		nb_layers++;
+
+		std::string layer_string = llformat("Clayers=%d",nb_layers);
+		codestream.access_siz()->parse_string(layer_string.c_str());
 		
 		// Set up data ordering, markers, etc... if precincts or blocks specified
+		// Note: This code is *not* used in the encoding made by the viewer. It is currently used only
+		// by llimage_libtest to create various j2c and test alternative compression schemes.
 		if ((mBlocksSize != -1) || (mPrecinctsSize != -1))
 		{
 			if (mPrecinctsSize != -1)
@@ -669,23 +668,26 @@ BOOL LLImageJ2CKDU::encodeImpl(LLImageJ2C &base, const LLImageRaw &raw_image, co
 				std::string blocks_string = llformat("Cblk={%d,%d}",mBlocksSize,mBlocksSize);
 				codestream.access_siz()->parse_string(blocks_string.c_str());
 			}
-			std::string ordering_string = llformat("Corder=RPCL");
+			std::string ordering_string = llformat("Corder=LRCP");
 			codestream.access_siz()->parse_string(ordering_string.c_str());
 			std::string PLT_string = llformat("ORGgen_plt=yes");
 			codestream.access_siz()->parse_string(PLT_string.c_str());
 			std::string Parts_string = llformat("ORGtparts=R");
 			codestream.access_siz()->parse_string(Parts_string.c_str());
 		}
+		
+		// Set the number of wavelets subresolutions (aka levels) 
 		if (mLevels != 0)
 		{
 			std::string levels_string = llformat("Clevels=%d",mLevels);
 			codestream.access_siz()->parse_string(levels_string.c_str());
 		}
 		
+		// Complete the encode settings
 		codestream.access_siz()->finalize_all();
 		codestream.change_appearance(transpose,vflip,hflip);
 
-		// Now we are ready for sample data processing.
+		// Now we are ready for sample data processing
 		kdc_flow_control *tile = new kdc_flow_control(&mem_in,codestream);
 		bool done = false;
 		while (!done)
@@ -702,7 +704,7 @@ BOOL LLImageJ2CKDU::encodeImpl(LLImageJ2C &base, const LLImageRaw &raw_image, co
 		}
 
 		// Produce the compressed output
-		codestream.flush(layer_bytes,num_layer_specs);
+		codestream.flush(layer_bytes,nb_layers);
 
 		// Cleanup
 		delete tile;
@@ -750,6 +752,207 @@ BOOL LLImageJ2CKDU::getMetadata(LLImageJ2C &base)
 	}
 }
 
+/*****************************************************************************/
+/* STATIC                        copy_block                                  */
+/*****************************************************************************/
+
+static void copy_block(kdu_block *in, kdu_block *out)
+{
+	if (in->K_max_prime != out->K_max_prime)
+    { 
+		std::cout << "Cannot copy blocks belonging to subbands with different quantization parameters." << std::endl; 
+		return;
+	}
+	if ((in->size.x != out->size.x) || (in->size.y != out->size.y))  
+    { 
+		std::cout << "Cannot copy code-blocks with different dimensions." << std::endl; 
+		return;
+	}
+	out->missing_msbs = in->missing_msbs;
+	if (out->max_passes < (in->num_passes+2))        // Gives us enough to round up
+		out->set_max_passes(in->num_passes+2,false); // to the next whole bit-plane
+	out->num_passes = in->num_passes;
+	int num_bytes = 0;
+	for (int z=0; z < in->num_passes; z++)
+    {
+		num_bytes += (out->pass_lengths[z] = in->pass_lengths[z]);
+		out->pass_slopes[z] = in->pass_slopes[z];
+    }
+	
+    // Just copy compressed code-bytes. Block transcoding not supported.
+	if (out->max_bytes < num_bytes)
+		out->set_max_bytes(num_bytes,false);
+	memcpy(out->byte_buffer,in->byte_buffer,(size_t) num_bytes);
+}
+
+/*****************************************************************************/
+/* STATIC                        copy_tile                                   */
+/*****************************************************************************/
+
+static void
+copy_tile(kdu_tile tile_in, kdu_tile tile_out, int tnum_in, int tnum_out,
+		  kdu_params *siz_in, kdu_params *siz_out, int skip_components,
+		  int &num_blocks)
+{
+	int num_components = tile_out.get_num_components();
+	int new_tpart=0, next_tpart = 1;
+	
+	for (int c=0; c < num_components; c++)
+    {
+		kdu_tile_comp comp_in, comp_out;
+		comp_in = tile_in.access_component(c);
+		comp_out = tile_out.access_component(c);
+		int num_resolutions = comp_out.get_num_resolutions();
+		//std::cout << "    Copying tile : num_resolutions = " << num_resolutions << std::endl;
+		for (int r=0; r < num_resolutions; r++)
+        {
+			kdu_resolution res_in;  res_in = comp_in.access_resolution(r);
+			kdu_resolution res_out; res_out = comp_out.access_resolution(r);
+			int b, min_band;
+			int num_bands = res_in.get_valid_band_indices(min_band);
+			std::cout << "        Copying tile : num_bands = " << num_bands << std::endl;
+			for (b=min_band; num_bands > 0; num_bands--, b++)
+            {
+				kdu_subband band_in;  band_in = res_in.access_subband(b);
+				kdu_subband band_out; band_out = res_out.access_subband(b);
+				kdu_dims blocks_in;  band_in.get_valid_blocks(blocks_in);
+				kdu_dims blocks_out; band_out.get_valid_blocks(blocks_out);
+				if ((blocks_in.size.x != blocks_out.size.x) ||
+					(blocks_in.size.y != blocks_out.size.y))
+                { 
+					std::cout << "Transcoding operation cannot proceed: Code-block partitions for the input and output code-streams do not agree." << std::endl;
+					return;
+				}
+				kdu_coords idx;
+				//std::cout << "            Copying tile : block indices, x = " << blocks_out.size.x << " and y = " << blocks_out.size.y << std::endl;
+				for (idx.y=0; idx.y < blocks_out.size.y; idx.y++)
+				{
+					for (idx.x=0; idx.x < blocks_out.size.x; idx.x++)
+					{
+						kdu_block *in =
+						band_in.open_block(idx+blocks_in.pos,&new_tpart);
+						for (; next_tpart <= new_tpart; next_tpart++)
+							siz_out->copy_from(siz_in,tnum_in,tnum_out,next_tpart,
+											   skip_components);
+						kdu_block *out = band_out.open_block(idx+blocks_out.pos);
+						copy_block(in,out);
+						band_in.close_block(in);
+						band_out.close_block(out);
+						num_blocks++;
+					}
+				}
+            }
+        }
+    }
+}
+
+// Find the block boundary for each discard level in the input image.
+// We parse the input blocks and copy them in a temporary output stream.
+// For the moment, we do nothing more that parsing the raw list of blocks and outputing result.
+void LLImageJ2CKDU::findDiscardLevelsBoundaries(LLImageJ2C &base)
+{
+	// We need the number of levels in that image before starting.
+	getMetadata(base);
+	
+	for (int discard_level = 0; discard_level < mLevels; discard_level++)
+	{
+		//std::cout << "Parsing discard level = " << discard_level << std::endl;
+		// Create the input codestream object.
+		setupCodeStream(base, TRUE, MODE_FAST);
+		mCodeStreamp->apply_input_restrictions(0, 4, discard_level, 0, NULL);
+		mCodeStreamp->set_max_bytes(KDU_LONG_MAX,true);
+		siz_params *siz_in = mCodeStreamp->access_siz();
+	
+		// Create the output codestream object.
+		siz_params siz;
+		siz.copy_from(siz_in,-1,-1,-1,0,discard_level,false,false,false);
+		siz.set(Scomponents,0,0,mCodeStreamp->get_num_components());
+	
+		U32 max_output_size = base.getWidth()*base.getHeight()*base.getComponents();
+		max_output_size = (max_output_size < 1000 ? 1000 : max_output_size);
+		U8 *output_buffer = new U8[max_output_size];
+		U32 output_size = 0; // Address updated by LLKDUMemTarget to give the final compressed buffer size
+		LLKDUMemTarget output(output_buffer, output_size, max_output_size);
+		kdu_codestream codestream_out; 
+		codestream_out.create(&siz,&output);
+		//codestream_out.share_buffering(*mCodeStreamp);
+		siz_params *siz_out = codestream_out.access_siz();
+		siz_out->copy_from(siz_in,-1,-1,-1,0,discard_level,false,false,false);
+		codestream_out.access_siz()->finalize_all(-1);
+	
+		// Set up rate control variables
+		kdu_long max_bytes = KDU_LONG_MAX;
+		kdu_params *cod = siz_out->access_cluster(COD_params);
+		int total_layers;  cod->get(Clayers,0,0,total_layers);
+		kdu_long *layer_bytes = new kdu_long[total_layers];
+		int nel, non_empty_layers = 0;
+	
+		// Now ready to perform the transfer of compressed data between streams
+		int flush_counter = INT_MAX;
+		kdu_dims tile_indices_in;  
+		mCodeStreamp->get_valid_tiles(tile_indices_in);
+		kdu_dims tile_indices_out; 
+		codestream_out.get_valid_tiles(tile_indices_out);
+		assert((tile_indices_in.size.x == tile_indices_out.size.x) &&
+			   (tile_indices_in.size.y == tile_indices_out.size.y));
+		int num_blocks=0;
+	
+		kdu_coords idx;
+		//std::cout << "Parsing tiles : x = " << tile_indices_out.size.x << " to y = " << tile_indices_out.size.y << std::endl;
+		for (idx.y=0; idx.y < tile_indices_out.size.y; idx.y++)
+		{
+			for (idx.x=0; idx.x < tile_indices_out.size.x; idx.x++)
+			{
+				kdu_tile tile_in = mCodeStreamp->open_tile(idx+tile_indices_in.pos);
+				int tnum_in = tile_in.get_tnum();
+				int tnum_out = idx.x + idx.y*tile_indices_out.size.x;
+				siz_out->copy_from(siz_in,tnum_in,tnum_out,0,0,discard_level,false,false,false);
+				siz_out->finalize_all(tnum_out);
+				// Note: do not open the output tile without first copying any tile-specific code-stream parameters
+				kdu_tile tile_out = codestream_out.open_tile(idx+tile_indices_out.pos);
+				assert(tnum_out == tile_out.get_tnum());
+				copy_tile(tile_in,tile_out,tnum_in,tnum_out,siz_in,siz_out,0,num_blocks);
+				tile_in.close();
+				tile_out.close();
+				flush_counter--;
+				if ((flush_counter <= 0) && codestream_out.ready_for_flush())
+				{
+					flush_counter = INT_MAX;
+					nel = codestream_out.trans_out(max_bytes,layer_bytes,total_layers);
+					non_empty_layers = (nel > non_empty_layers)?nel:non_empty_layers;
+				}
+			}
+		}
+	
+		// Generate the output code-stream
+		if (codestream_out.ready_for_flush())
+		{
+			nel = codestream_out.trans_out(max_bytes,layer_bytes,total_layers);
+			non_empty_layers = (nel > non_empty_layers)?nel:non_empty_layers;
+		}
+		if (non_empty_layers > total_layers)
+			non_empty_layers = total_layers; // Can happen if a tile has more layers
+	
+		// Print out stats
+		std::cout << "Code stream parsing for discard level = " << discard_level << std::endl;
+		std::cout << "    Total compressed memory in  = " << mCodeStreamp->get_compressed_data_memory() << " bytes" << std::endl;
+		std::cout << "    Total compressed memory out = " << codestream_out.get_compressed_data_memory() << " bytes" << std::endl;
+		//std::cout << "    Output contains " << total_layers << " quality layers" << std::endl;		
+		std::cout << "    Transferred " << num_blocks << " code-blocks from in to out" << std::endl;
+		//std::cout << "    Read " << mCodeStreamp->get_num_tparts() << " tile-part(s) from a total of " << (int) tile_indices_in.area() << " tile(s)" << std::endl;
+		std::cout << "    Total bytes read = " << mCodeStreamp->get_total_bytes() << std::endl;
+		//std::cout << "    Wrote " << codestream_out.get_num_tparts() << " tile-part(s) in a total of " << (int) tile_indices_out.area() << " tile(s)" << std::endl;
+		std::cout << "    Total bytes written = " << codestream_out.get_total_bytes() << std::endl;
+		std::cout << "-------------" << std::endl;
+	
+		// Clean-up
+		cleanupCodeStream();
+		codestream_out.destroy();
+		delete[] output_buffer;	
+	}
+	return;
+}
+
 void set_default_colour_weights(kdu_params *siz)
 {
 	kdu_params *cod = siz->access_cluster(COD_params);
diff --git a/indra/llkdu/llimagej2ckdu.h b/indra/llkdu/llimagej2ckdu.h
index 1489dbf704..9ab0b9e4a7 100644
--- a/indra/llkdu/llimagej2ckdu.h
+++ b/indra/llkdu/llimagej2ckdu.h
@@ -60,6 +60,7 @@ protected:
 								BOOL reversible=FALSE);
 	/*virtual*/ BOOL initDecode(LLImageJ2C &base, LLImageRaw &raw_image, int discard_level = -1, int* region = NULL);
 	/*virtual*/ BOOL initEncode(LLImageJ2C &base, LLImageRaw &raw_image, int blocks_size = -1, int precincts_size = -1, int levels = 0);
+	void findDiscardLevelsBoundaries(LLImageJ2C &base);
 
 private:
 	BOOL initDecode(LLImageJ2C &base, LLImageRaw &raw_image, F32 decode_time, ECodeStreamMode mode, S32 first_channel, S32 max_channel_count, int discard_level = -1, int* region = NULL);
diff --git a/indra/llkdu/tests/llimagej2ckdu_test.cpp b/indra/llkdu/tests/llimagej2ckdu_test.cpp
index ab60ab6d50..beee99a522 100644
--- a/indra/llkdu/tests/llimagej2ckdu_test.cpp
+++ b/indra/llkdu/tests/llimagej2ckdu_test.cpp
@@ -29,6 +29,7 @@
 // Class to test 
 #include "llimagej2ckdu.h"
 #include "llkdumem.h"
+#include "kdu_block_coding.h"
 // Tut header
 #include "lltut.h"
 
@@ -86,7 +87,7 @@ void LLImageFormatted::resetLastError() { }
 void LLImageFormatted::sanityCheck() { }
 void LLImageFormatted::setLastError(const std::string& , const std::string& ) { }
 
-LLImageJ2C::LLImageJ2C() : LLImageFormatted(IMG_CODEC_J2C) { }
+LLImageJ2C::LLImageJ2C() : LLImageFormatted(IMG_CODEC_J2C), mRate(DEFAULT_COMPRESSION_RATE) { }
 LLImageJ2C::~LLImageJ2C() { }
 S32 LLImageJ2C::calcDataSize(S32 ) { return 0; }
 S32 LLImageJ2C::calcDiscardLevelBytes(S32 ) { return 0; }
@@ -107,16 +108,25 @@ bool LLKDUMemIn::get(int, kdu_line_buf&, int) { return false; }
 
 // Stub Kakadu Library calls
 kdu_tile_comp kdu_tile::access_component(int ) { kdu_tile_comp a; return a; }
+kdu_block_encoder::kdu_block_encoder() { }
+kdu_block_decoder::kdu_block_decoder() { }
+void kdu_block::set_max_passes(int , bool ) { }
+void kdu_block::set_max_bytes(int , bool ) { }
+void kdu_block::set_max_samples(int ) { }
 void kdu_tile::close(kdu_thread_env* ) { }
 int kdu_tile::get_num_components() { return 0; }
 bool kdu_tile::get_ycc() { return false; }
 void kdu_tile::set_components_of_interest(int , const int* ) { }
+int kdu_tile::get_tnum() { return 0; }
 kdu_resolution kdu_tile_comp::access_resolution() { kdu_resolution a; return a; }
+kdu_resolution kdu_tile_comp::access_resolution(int ) { kdu_resolution a; return a; }
 int kdu_tile_comp::get_bit_depth(bool ) { return 8; }
 bool kdu_tile_comp::get_reversible() { return false; }
+int kdu_tile_comp::get_num_resolutions() { return 1; }
 kdu_subband kdu_resolution::access_subband(int ) { kdu_subband a; return a; }
 void kdu_resolution::get_dims(kdu_dims& ) { }
 int kdu_resolution::which() { return 0; }
+int kdu_resolution::get_valid_band_indices(int &) { return 1; }
 kdu_decoder::kdu_decoder(kdu_subband , kdu_sample_allocator*, bool , float, int, kdu_thread_env*, kdu_thread_queue*) { }
 kdu_synthesis::kdu_synthesis(kdu_resolution, kdu_sample_allocator*, bool, float, kdu_thread_env*, kdu_thread_queue*) { }
 kdu_params::kdu_params(const char*, bool, bool, bool, bool, bool) { }
@@ -124,6 +134,7 @@ kdu_params::~kdu_params() { }
 void kdu_params::set(const char* , int , int , bool ) { }
 void kdu_params::set(const char* , int , int , int ) { }
 void kdu_params::finalize_all(bool ) { }
+void kdu_params::finalize_all(int, bool ) { }
 void kdu_params::copy_from(kdu_params*, int, int, int, int, int, bool, bool, bool) { }
 bool kdu_params::parse_string(const char*) { return false; }
 bool kdu_params::get(const char*, int, int, bool&, bool, bool, bool) { return false; }
@@ -135,6 +146,7 @@ void kdu_codestream::set_fast() { }
 void kdu_codestream::set_fussy() { }
 void kdu_codestream::get_dims(int, kdu_dims&, bool ) { }
 int kdu_codestream::get_min_dwt_levels() { return 5; }
+int kdu_codestream::get_max_tile_layers() { return 1; }
 void kdu_codestream::change_appearance(bool, bool, bool) { }
 void kdu_codestream::get_tile_dims(kdu_coords, int, kdu_dims&, bool ) { }
 void kdu_codestream::destroy() { }
@@ -148,9 +160,18 @@ void kdu_codestream::get_subsampling(int , kdu_coords&, bool ) { }
 void kdu_codestream::flush(kdu_long *, int , kdu_uint16 *, bool, bool, double, kdu_thread_env*) { }
 void kdu_codestream::set_resilient(bool ) { }
 int kdu_codestream::get_num_components(bool ) { return 0; }
+kdu_long kdu_codestream::get_total_bytes(bool ) { return 0; }
+kdu_long kdu_codestream::get_compressed_data_memory(bool ) {return 0; }
+void kdu_codestream::share_buffering(kdu_codestream ) { }
+int kdu_codestream::get_num_tparts() { return 0; }
+int kdu_codestream::trans_out(kdu_long, kdu_long*, int, bool, kdu_thread_env* ) { return 0; }
+bool kdu_codestream::ready_for_flush(kdu_thread_env*) { return false; }
 siz_params* kdu_codestream::access_siz() { return NULL; }
 kdu_tile kdu_codestream::open_tile(kdu_coords , kdu_thread_env* ) { kdu_tile a; return a; }
 kdu_codestream_comment kdu_codestream::add_comment() { kdu_codestream_comment a; return a; }
+void kdu_subband::close_block(kdu_block*, kdu_thread_env*) { }
+void kdu_subband::get_valid_blocks(kdu_dims &indices) { }
+kdu_block* kdu_subband::open_block(kdu_coords, int*, kdu_thread_env*) { return NULL; }
 bool kdu_codestream_comment::put_text(const char*) { return false; }
 void kdu_customize_warnings(kdu_message*) { }
 void kdu_customize_errors(kdu_message*) { }
diff --git a/indra/newview/app_settings/settings.xml b/indra/newview/app_settings/settings.xml
index 9fff543b13..5fc9c5d863 100755
--- a/indra/newview/app_settings/settings.xml
+++ b/indra/newview/app_settings/settings.xml
@@ -10686,6 +10686,17 @@
       <key>Value</key>
       <integer>0</integer>
     </map>
+    <key>TextureNewByteRange</key>
+    <map>
+      <key>Comment</key>
+      <string>Use the new more accurate byte range computation for j2c discard levels</string>
+      <key>Persist</key>
+      <integer>1</integer>
+      <key>Type</key>
+      <string>Boolean</string>
+      <key>Value</key>
+      <integer>1</integer>
+    </map>
     <key>TexturePickerShowFolders</key>
     <map>
       <key>Comment</key>
diff --git a/indra/newview/llappviewer.cpp b/indra/newview/llappviewer.cpp
index 98a83175a7..9a52ee4312 100644
--- a/indra/newview/llappviewer.cpp
+++ b/indra/newview/llappviewer.cpp
@@ -1950,7 +1950,7 @@ bool LLAppViewer::initThreads()
 	static const bool enable_threads = true;
 #endif
 
-	LLImage::initClass();
+	LLImage::initClass(gSavedSettings.getBOOL("TextureNewByteRange"));
 
 	LLVFSThread::initClass(enable_threads && false);
 	LLLFSThread::initClass(enable_threads && false);
diff --git a/indra/newview/llspatialpartition.cpp b/indra/newview/llspatialpartition.cpp
index 5d196a465f..b7a5eea27c 100644
--- a/indra/newview/llspatialpartition.cpp
+++ b/indra/newview/llspatialpartition.cpp
@@ -3647,6 +3647,110 @@ void renderShadowFrusta(LLDrawInfo* params)
 	gGL.setSceneBlendType(LLRender::BT_ALPHA);
 }
 
+void renderTexelDensity(LLDrawable* drawable)
+{
+	if (LLViewerTexture::sDebugTexelsMode == LLViewerTexture::DEBUG_TEXELS_OFF
+		|| LLViewerTexture::sCheckerBoardImagep.isNull())
+	{
+		return;
+	}
+
+	LLGLEnable _(GL_BLEND);
+	//gObjectFullbrightProgram.bind();
+
+	LLMatrix4 checkerboard_matrix;
+	S32 discard_level = -1;
+
+	for (S32 f = 0; f < drawable->getNumFaces(); f++)
+	{
+		LLFace* facep = drawable->getFace(f);
+		LLVertexBuffer* buffer = facep->getVertexBuffer();
+		LLViewerTexture* texturep = facep->getTexture();
+
+		if (texturep == NULL) continue;
+
+		switch(LLViewerTexture::sDebugTexelsMode)
+		{
+		case LLViewerTexture::DEBUG_TEXELS_CURRENT:
+			discard_level = -1;
+			break;
+		case LLViewerTexture::DEBUG_TEXELS_DESIRED:
+			{
+				LLViewerFetchedTexture* fetched_texturep = dynamic_cast<LLViewerFetchedTexture*>(texturep);
+				discard_level = fetched_texturep ? fetched_texturep->getDesiredDiscardLevel() : -1;
+				break;
+			}
+		default:
+		case LLViewerTexture::DEBUG_TEXELS_FULL:
+			discard_level = 0;
+			break;
+		}
+
+		checkerboard_matrix.initScale(LLVector3(texturep->getWidth(discard_level) / 8, texturep->getHeight(discard_level) / 8, 1.f));
+
+		gGL.getTexUnit(0)->bind(LLViewerTexture::sCheckerBoardImagep, TRUE);
+		gGL.matrixMode(LLRender::MM_TEXTURE);
+		gGL.loadMatrix((GLfloat*)&checkerboard_matrix.mMatrix);
+
+		if (buffer && (facep->getGeomCount() >= 3))
+		{
+			buffer->setBuffer(LLVertexBuffer::MAP_VERTEX | LLVertexBuffer::MAP_TEXCOORD0);
+			U16 start = facep->getGeomStart();
+			U16 end = start + facep->getGeomCount()-1;
+			U32 count = facep->getIndicesCount();
+			U16 offset = facep->getIndicesStart();
+			buffer->drawRange(LLRender::TRIANGLES, start, end, count, offset);
+		}
+
+		gGL.loadIdentity();
+		gGL.matrixMode(LLRender::MM_MODELVIEW);
+	}
+
+	//S32 num_textures = llmax(1, (S32)params->mTextureList.size());
+
+	//for (S32 i = 0; i < num_textures; i++)
+	//{
+	//	LLViewerTexture* texturep = params->mTextureList.empty() ? params->mTexture.get() : params->mTextureList[i].get();
+	//	if (texturep == NULL) continue;
+
+	//	LLMatrix4 checkboard_matrix;
+	//	S32 discard_level = -1;
+	//	switch(LLViewerTexture::sDebugTexelsMode)
+	//	{
+	//	case LLViewerTexture::DEBUG_TEXELS_CURRENT:
+	//		discard_level = -1;
+	//		break;
+	//	case LLViewerTexture::DEBUG_TEXELS_DESIRED:
+	//		{
+	//			LLViewerFetchedTexture* fetched_texturep = dynamic_cast<LLViewerFetchedTexture*>(texturep);
+	//			discard_level = fetched_texturep ? fetched_texturep->getDesiredDiscardLevel() : -1;
+	//			break;
+	//		}
+	//	default:
+	//	case LLViewerTexture::DEBUG_TEXELS_FULL:
+	//		discard_level = 0;
+	//		break;
+	//	}
+
+	//	checkboard_matrix.initScale(LLVector3(texturep->getWidth(discard_level) / 8, texturep->getHeight(discard_level) / 8, 1.f));
+	//	gGL.getTexUnit(i)->activate();
+
+	//	glMatrixMode(GL_TEXTURE);
+	//	glPushMatrix();
+	//	glLoadIdentity();
+	//	//gGL.matrixMode(LLRender::MM_TEXTURE);
+	//	glLoadMatrixf((GLfloat*) checkboard_matrix.mMatrix);
+
+	//	gGL.getTexUnit(i)->bind(LLViewerTexture::sCheckerBoardImagep, TRUE);
+
+	//	pushVerts(params, LLVertexBuffer::MAP_VERTEX | LLVertexBuffer::MAP_TEXCOORD0 | LLVertexBuffer::MAP_COLOR | LLVertexBuffer::MAP_NORMAL );
+
+	//	glPopMatrix();
+	//	glMatrixMode(GL_MODELVIEW);
+	//	//gGL.matrixMode(LLRender::MM_MODELVIEW);
+	//}
+}
+
 
 void renderLights(LLDrawable* drawablep)
 {
@@ -4042,6 +4146,10 @@ public:
 			{
 				renderComplexityDisplay(drawable);
 			}
+			if(gPipeline.hasRenderDebugMask(LLPipeline::RENDER_DEBUG_TEXEL_DENSITY))
+			{
+				renderTexelDensity(drawable);
+			}
 
 			LLVOAvatar* avatar = dynamic_cast<LLVOAvatar*>(drawable->getVObj().get());
 			
@@ -4291,7 +4399,8 @@ void LLSpatialPartition::renderDebug()
 									  LLPipeline::RENDER_DEBUG_AGENT_TARGET |
 									  //LLPipeline::RENDER_DEBUG_BUILD_QUEUE |
 									  LLPipeline::RENDER_DEBUG_SHADOW_FRUSTA |
-									  LLPipeline::RENDER_DEBUG_RENDER_COMPLEXITY)) 
+									  LLPipeline::RENDER_DEBUG_RENDER_COMPLEXITY |
+									  LLPipeline::RENDER_DEBUG_TEXEL_DENSITY)) 
 	{
 		return;
 	}
diff --git a/indra/newview/lltexlayer.cpp b/indra/newview/lltexlayer.cpp
index 1693cfc9e2..467115c928 100644
--- a/indra/newview/lltexlayer.cpp
+++ b/indra/newview/lltexlayer.cpp
@@ -497,7 +497,6 @@ void LLTexLayerSetBuffer::doUpload()
 	}
 	
 	LLPointer<LLImageJ2C> compressedImage = new LLImageJ2C;
-	compressedImage->setRate(0.f);
 	const char* comment_text = LINDEN_J2C_COMMENT_PREFIX "RGBHM"; // writes into baked_color_data. 5 channels (rgb, heightfield/alpha, mask)
 	if (compressedImage->encode(baked_image, comment_text))
 	{
diff --git a/indra/newview/llviewermenu.cpp b/indra/newview/llviewermenu.cpp
index 301b78ad4e..7bdfd6df1d 100644
--- a/indra/newview/llviewermenu.cpp
+++ b/indra/newview/llviewermenu.cpp
@@ -845,6 +845,73 @@ class LLAdvancedCheckFeature : public view_listener_t
 }
 };
 
+class LLAdvancedCheckDisplayTextureDensity : public view_listener_t
+{
+	bool handleEvent(const LLSD& userdata)
+	{
+		std::string mode = userdata.asString();
+		if (!gPipeline.hasRenderDebugMask(LLPipeline::RENDER_DEBUG_TEXEL_DENSITY))
+		{
+			return mode == "none";
+		}
+		if (mode == "current")
+		{
+			return LLViewerTexture::sDebugTexelsMode == LLViewerTexture::DEBUG_TEXELS_CURRENT;
+		}
+		else if (mode == "desired")
+		{
+			return LLViewerTexture::sDebugTexelsMode == LLViewerTexture::DEBUG_TEXELS_DESIRED;
+		}
+		else if (mode == "full")
+		{
+			return LLViewerTexture::sDebugTexelsMode == LLViewerTexture::DEBUG_TEXELS_FULL;
+		}
+		return false;
+	}
+};
+
+class LLAdvancedSetDisplayTextureDensity : public view_listener_t
+{
+	bool handleEvent(const LLSD& userdata)
+	{
+		std::string mode = userdata.asString();
+		if (mode == "none")
+		{
+			if (gPipeline.hasRenderDebugMask(LLPipeline::RENDER_DEBUG_TEXEL_DENSITY) == TRUE) 
+			{
+				gPipeline.toggleRenderDebug((void*)LLPipeline::RENDER_DEBUG_TEXEL_DENSITY);
+			}
+			LLViewerTexture::sDebugTexelsMode = LLViewerTexture::DEBUG_TEXELS_OFF;
+		}
+		else if (mode == "current")
+		{
+			if (gPipeline.hasRenderDebugMask(LLPipeline::RENDER_DEBUG_TEXEL_DENSITY) == FALSE) 
+			{
+				gPipeline.toggleRenderDebug((void*)LLPipeline::RENDER_DEBUG_TEXEL_DENSITY);
+			}
+			LLViewerTexture::sDebugTexelsMode = LLViewerTexture::DEBUG_TEXELS_CURRENT;
+		}
+		else if (mode == "desired")
+		{
+			if (gPipeline.hasRenderDebugMask(LLPipeline::RENDER_DEBUG_TEXEL_DENSITY) == FALSE) 
+			{
+				gPipeline.toggleRenderDebug((void*)LLPipeline::RENDER_DEBUG_TEXEL_DENSITY);
+			}
+			gPipeline.setRenderDebugFeatureControl(LLPipeline::RENDER_DEBUG_TEXEL_DENSITY, true);
+			LLViewerTexture::sDebugTexelsMode = LLViewerTexture::DEBUG_TEXELS_DESIRED;
+		}
+		else if (mode == "full")
+		{
+			if (gPipeline.hasRenderDebugMask(LLPipeline::RENDER_DEBUG_TEXEL_DENSITY) == FALSE) 
+			{
+				gPipeline.toggleRenderDebug((void*)LLPipeline::RENDER_DEBUG_TEXEL_DENSITY);
+			}
+			LLViewerTexture::sDebugTexelsMode = LLViewerTexture::DEBUG_TEXELS_FULL;
+		}
+		return true;
+	}
+};
+
 
 //////////////////
 // INFO DISPLAY //
@@ -959,6 +1026,10 @@ U32 info_display_from_string(std::string info_display)
 	{
 		return LLPipeline::RENDER_DEBUG_WIND_VECTORS;
 	}
+	else if ("texel density" == info_display)
+	{
+		return LLPipeline::RENDER_DEBUG_TEXEL_DENSITY;
+	}
 	else
 	{
 		return 0;
@@ -8104,6 +8175,10 @@ void initialize_menus()
 	//// Advanced > Render > Features
 	view_listener_t::addMenu(new LLAdvancedToggleFeature(), "Advanced.ToggleFeature");
 	view_listener_t::addMenu(new LLAdvancedCheckFeature(), "Advanced.CheckFeature");
+
+	view_listener_t::addMenu(new LLAdvancedCheckDisplayTextureDensity(), "Advanced.CheckDisplayTextureDensity");
+	view_listener_t::addMenu(new LLAdvancedSetDisplayTextureDensity(), "Advanced.SetDisplayTextureDensity");
+
 	// Advanced > Render > Info Displays
 	view_listener_t::addMenu(new LLAdvancedToggleInfoDisplay(), "Advanced.ToggleInfoDisplay");
 	view_listener_t::addMenu(new LLAdvancedCheckInfoDisplay(), "Advanced.CheckInfoDisplay");
diff --git a/indra/newview/llviewertexture.cpp b/indra/newview/llviewertexture.cpp
index 0360a8faf0..2efc9ad4d0 100644
--- a/indra/newview/llviewertexture.cpp
+++ b/indra/newview/llviewertexture.cpp
@@ -67,6 +67,7 @@
 // statics
 LLPointer<LLViewerTexture>        LLViewerTexture::sNullImagep = NULL;
 LLPointer<LLViewerTexture>        LLViewerTexture::sBlackImagep = NULL;
+LLPointer<LLViewerTexture>        LLViewerTexture::sCheckerBoardImagep = NULL;
 LLPointer<LLViewerFetchedTexture> LLViewerFetchedTexture::sMissingAssetImagep = NULL;
 LLPointer<LLViewerFetchedTexture> LLViewerFetchedTexture::sWhiteImagep = NULL;
 LLPointer<LLViewerFetchedTexture> LLViewerFetchedTexture::sDefaultImagep = NULL;
@@ -96,6 +97,7 @@ S32 LLViewerTexture::sMaxSmallImageSize = MAX_CACHED_RAW_IMAGE_AREA ;
 BOOL LLViewerTexture::sFreezeImageScalingDown = FALSE ;
 F32 LLViewerTexture::sCurrentTime = 0.0f ;
 BOOL LLViewerTexture::sUseTextureAtlas        = FALSE ;
+LLViewerTexture::EDebugTexels LLViewerTexture::sDebugTexelsMode = LLViewerTexture::DEBUG_TEXELS_OFF;
 
 const F32 desired_discard_bias_min = -2.0f; // -max number of levels to improve image quality by
 const F32 desired_discard_bias_max = (F32)MAX_DISCARD_LEVEL; // max number of levels to reduce image quality by
@@ -347,6 +349,21 @@ void LLViewerTextureManager::init()
  	LLViewerFetchedTexture::sSmokeImagep = LLViewerTextureManager::getFetchedTexture(IMG_SMOKE, TRUE, LLViewerTexture::BOOST_UI);
 	LLViewerFetchedTexture::sSmokeImagep->setNoDelete() ;
 
+	image_raw = new LLImageRaw(32,32,3);
+	data = image_raw->getData();
+
+	for (S32 i = 0; i < (32*32*3); i+=3)
+	{
+		S32 x = (i % (32*3)) / (3*16);
+		S32 y = i / (32*3*16);
+		U8 color = ((x + y) % 2) * 255;
+		data[i] = color;
+		data[i+1] = color;
+		data[i+2] = color;
+	}
+
+	LLViewerTexture::sCheckerBoardImagep = LLViewerTextureManager::getLocalTexture(image_raw.get(), TRUE);
+
 	LLViewerTexture::initClass() ;
 
 	if (LLMetricPerformanceTesterBasic::isMetricLogRequested(sTesterName) && !LLMetricPerformanceTesterBasic::getTester(sTesterName))
diff --git a/indra/newview/llviewertexture.h b/indra/newview/llviewertexture.h
index b96441127d..99053a8ccc 100644
--- a/indra/newview/llviewertexture.h
+++ b/indra/newview/llviewertexture.h
@@ -139,6 +139,7 @@ public:
 		OTHER,
 		MAX_GL_IMAGE_CATEGORY
 	};
+
 	static S32 getTotalNumOfCategories() ;
 	static S32 getIndexFromCategory(S32 category) ;
 	static S32 getCategoryFromIndex(S32 index) ;
@@ -330,8 +331,19 @@ public:
 	static F32  sCurrentTime ;
 	static BOOL sUseTextureAtlas ;
 
+	enum EDebugTexels
+	{
+		DEBUG_TEXELS_OFF,
+		DEBUG_TEXELS_CURRENT,
+		DEBUG_TEXELS_DESIRED,
+		DEBUG_TEXELS_FULL
+	};
+
+	static EDebugTexels sDebugTexelsMode;
+
 	static LLPointer<LLViewerTexture> sNullImagep; // Null texture for non-textured objects.
 	static LLPointer<LLViewerTexture> sBlackImagep;	// Texture to show NOTHING (pure black)
+	static LLPointer<LLViewerTexture> sCheckerBoardImagep;	// Texture to show NOTHING (pure black)
 };
 
 
diff --git a/indra/newview/llviewertexturelist.cpp b/indra/newview/llviewertexturelist.cpp
index 089f45ca89..54ae519422 100644
--- a/indra/newview/llviewertexturelist.cpp
+++ b/indra/newview/llviewertexturelist.cpp
@@ -1030,7 +1030,6 @@ LLPointer<LLImageJ2C> LLViewerTextureList::convertToUploadFile(LLPointer<LLImage
 {
 	raw_image->biasedScaleToPowerOfTwo(LLViewerFetchedTexture::MAX_IMAGE_SIZE_DEFAULT);
 	LLPointer<LLImageJ2C> compressedImage = new LLImageJ2C();
-	compressedImage->setRate(0.f);
 	
 	if (gSavedSettings.getBOOL("LosslessJ2CUpload") &&
 		(raw_image->getWidth() * raw_image->getHeight() <= LL_IMAGE_REZ_LOSSLESS_CUTOFF * LL_IMAGE_REZ_LOSSLESS_CUTOFF))
diff --git a/indra/newview/pipeline.h b/indra/newview/pipeline.h
index 9c78048c46..670a23ef14 100644
--- a/indra/newview/pipeline.h
+++ b/indra/newview/pipeline.h
@@ -461,6 +461,7 @@ public:
 		RENDER_DEBUG_LOD_INFO	        = 0x04000000,
 		RENDER_DEBUG_RENDER_COMPLEXITY  = 0x08000000,
 		RENDER_DEBUG_ATTACHMENT_BYTES	= 0x10000000,
+		RENDER_DEBUG_TEXEL_DENSITY		= 0x20000000
 	};
 
 public:
diff --git a/indra/newview/skins/default/xui/en/menu_viewer.xml b/indra/newview/skins/default/xui/en/menu_viewer.xml
index 58fd1ac829..8b0152b1a2 100644
--- a/indra/newview/skins/default/xui/en/menu_viewer.xml
+++ b/indra/newview/skins/default/xui/en/menu_viewer.xml
@@ -2417,6 +2417,52 @@
            function="Advanced.ToggleInfoDisplay"
            parameter="sculpt" />
 		</menu_item_check>
+       <menu
+         create_jump_keys="true"
+         label="Texture Density"
+         name="Texture Density"
+         tear_off="true">
+          <menu_item_check
+           label="None"
+           name="None">
+            <menu_item_check.on_check
+             function="Advanced.CheckDisplayTextureDensity"
+             parameter="none" />
+            <menu_item_check.on_click
+             function="Advanced.SetDisplayTextureDensity"
+             parameter="none" />
+          </menu_item_check>
+          <menu_item_check
+           label="Current"
+           name="Current">
+            <menu_item_check.on_check
+             function="Advanced.CheckDisplayTextureDensity"
+             parameter="current" />
+            <menu_item_check.on_click
+             function="Advanced.SetDisplayTextureDensity"
+             parameter="current" />
+          </menu_item_check>
+          <menu_item_check
+           label="Desired"
+           name="Desired">
+            <menu_item_check.on_check
+             function="Advanced.CheckDisplayTextureDensity"
+             parameter="desired" />
+            <menu_item_check.on_click
+             function="Advanced.SetDisplayTextureDensity"
+             parameter="desired" />
+          </menu_item_check>
+          <menu_item_check
+           label="Full"
+           name="Full">
+            <menu_item_check.on_check
+             function="Advanced.CheckDisplayTextureDensity"
+             parameter="full" />
+            <menu_item_check.on_click
+             function="Advanced.SetDisplayTextureDensity"
+             parameter="full" />
+          </menu_item_check>
+        </menu>
       </menu>
         <menu
          create_jump_keys="true"