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Topic: Lumi masking

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	Lumi masking - Encyclopedia, History, Geography and Biography (Site not responding. Last check: 2007-10-13)
		Lumi masking is a technique used by video compression software, most notably XviD, which reduces quality in very bright or very dark areas of the picture, as quality loss in these areas is less likely to be visible.
		The reduction in quality (and therefore bitrate) in certain areas of the picture caused by using lumi masking allows more bits to be allocated to the rest of the video, thus improving overall quality.
		Lumi masking is not perfect, however, and in some cases the degredation in quality it causes is visible.
	www.arikah.net /encyclopedia/Lumi_masking (152 words)

	Lumi masking
		Lumi masking is a technique used by video compression software, which reduces quality in very bright or very dark areas of the picture, as quality loss in these areas is less likely to be visible.
		Lumi masking is not perfect, however, and in some cases the degradation in quality it causes is visible.
		Lumi is Finnish for snow but in this context it is more likely to mean luma (or luminance) than the Finnish meaning.
	encycl.opentopia.com /term/Lumi_masking (147 words)

	lumi masking - Doom9's Forum
		Here are the results of the lumi masking test done with the 08082002-1 build.
		The same movie is encoded twice, with the exact same parameters, except that in one encode lumi masking is used in both passes, and in the other no lumi masking is used at all.
		First of all, it is very clear that using lumi masking in both passes is very helpful in terms of increasing compressibility (LUMI: 54.20%, NOLUMI: 51.84%) and in terms of reaching lower quantizers (obviously more 2 and 3 quantizers) for the movie.
	forum.doom9.org /showthread.php?mode=hybrid&t=31301&highlight=iago+mpeg2dec3 (1805 words)

	[XviD-devel] Adaptive quantisation
		The luminance masking code can only _increase_ quantizers for certain blocks, which means a degradation in quality.
		I've looked at the lumi masking code itself right now and the approach is not wrong, but isn't perfect either.
		When I was writing my luminance masking code, I tried this approach at first but dropped it because it causes problems in overall dark or overall bright frames: The new code (obviously written by ProfDrMorph) calculates the relative luminance of a block (relative to the global luminance).
	list.xvid.org /pipermail/xvid-devel/2002-August/000250.html (633 words)

	bitrate at xvid [Archive] - Doom9's Forum
		I have encoded it 2 pass, first using lumi masking and second withpot it, but for first scene bitrate was still very high and for second I got macroblockes.
		Doing one pass with luma masking and one pass without it surely makes the ".stats" file wrong in a way since the information the codec gathered differs in a way from what the codec compresses in the second pass.
		If you're going to use lumi masking with the goal of high-quality output, I'd consider setting the maximum quantizer to 6 or 7 (Advanced tab).
	forum.doom9.org /archive/index.php/t-13953.html (3350 words)

	Re: [XviD-devel] Adaptive quantisation
		Blockyness can be caused by a lot of things, simplest is that the quantizers were too high (could be caused by lumi masking - btw: was lumi masking activated for the SPR encode at all?), worst would be a serious problem within core.
		Luma masking was activated, and I asked Doom9 to tell me where the quantizers range around.
		The bitrates I get with the matrix now in the 1st pass are amazing compared to those with the former code, but I'm not sure if this is really good as it could have visual impact (I mean this as in: very easy to see).
	itdp.de /Xvid-devel/2002-08/msg00042.html (369 words)

	codec/ffmpeg/libavcodec/avcodec.h (Site not responding. Last check: 2007-10-13)
		1140 * - encoding: set by user 1141 * - decoding: unused 1142 / 1143 float lumi_masking; 1144 1145 /* 1146 * temporary complexity masking (0-> disabled).
		1147 * - encoding: set by user 1148 * - decoding: unused 1149 / 1150 float temporal_cplx_masking; 1151 1152 /* 1153 * spatial complexity masking (0-> disabled).
		1154 * - encoding: set by user 1155 * - decoding: unused 1156 / 1157 float spatial_cplx_masking; 1158 1159 /* 1160 * p block masking (0-> disabled).
	vic2.nchc.org.tw /lxr/http/source/ffmpeg/libavcodec/avcodec.h (2216 words)

	ffmpeg-0.4.8/libavcodec/avcodec.h
		853 * - encoding: set by user 854 * - decoding: unused 855 / 856 float lumi_masking; 857 858 /* 859 * temporary complexity masking (0-> disabled).
		860 * - encoding: set by user 861 * - decoding: unused 862 / 863 float temporal_cplx_masking; 864 865 /* 866 * spatial complexity masking (0-> disabled).
		867 * - encoding: set by user 868 * - decoding: unused 869 / 870 float spatial_cplx_masking; 871 872 /* 873 * p block masking (0-> disabled).
	lxr-itec.uni-klu.ac.at /ffmpeg/source/libavcodec/avcodec.h (2681 words)

	[XviD-devel] API 3.0 (Site not responding. Last check: 2007-10-13)
		As part of general cleanup, this should be done.
		For the API, it's only important that LUMI must only be used if ADAPTIVEQUANT is enabled.
		It was only used during a short period after Michael changed position of INTER/INTRA decision.
	list.xvid.org /pipermail/xvid-devel/2002-September/000690.html (202 words)

	XviD
		The momentary stable version is 1,1 from 30 December 2005 and supports the Mpeg-4 Advanced of profiles.
		That is, XviD supports now Advanced simple profiles features such as b-Frames, Quarter pixel Motion Compensation, global Motion Compensation, Lumi Masking, Trellis Quantization and Custom quantum stencils.
		Sigma Design was informed and confirmed the fact that a programmer REALmagic on XviD had constructed - in addition, insured that it would replace all GPL code, in order to avoid copyright infringements.
	www.slotsch.de /english/html/xvid.html (641 words)

	Nabble - k3b translating (Site not responding. Last check: 2007-10-13)
		global and quarter pixel motion compensation, lumi masking, trellis
		> global and quarter pixel motion compensation, lumi masking, trellis
		> 'lumi' an 'trellis' has to be translated?
	www.nabble.com /k3b-translating-t2703883.html (311 words)

	[No title] (Site not responding. Last check: 2007-10-13)
		Leave all the other options at default unless you are experimenting.
		If you want to use lumi masking, make sure you enable it in both passes.
		Click OK and choose file --> save as avi, name the file, check the "add this job to job control" tickbox and click OK. Now go back to the codec options and choose 2 pass - 2nd pass int.
	www.cs.bris.ac.uk /home/ao2828/MPEG-4.html (1028 words)

	XviD (Site not responding. Last check: 2007-10-13)
		The current stable release is 0.9.2 and supports the MPEG-4 Simple Profile.
		Unstable builds include Advanced Simple Profile features such as b-frames, quarter pixel motion compensation, global motion compensation, lumi masking, and Trellis quantization, in varying stages of completion.
		Because of patent laws, XviD is not licensed to people/firms in the US or Japan.
	www.portaljuice.com /xvid.html (496 words)

	Koepi's Media Development Homepage (Site not responding. Last check: 2007-10-13)
		It has some nice new features which you should try.
		Small fixes for the unstable XviD build: lumi masking should now really produce no random spots, and the binary is compiled with old optimizations as they were faster.
		New unstable developer XviD build with plenty additions: dynamic halfpel/ quarterpel decision, refdivx' lumi masking code is fixed,...
	www.koepi.org /oldnews/0103.html (705 words)

	Codecs - Conclusion
		The official line is that if you want to have a reasonably stable build you should use the latest trusted snapshot (in this case 0412).
		In the aftermath of this test it was discovered that the lumi masking code being used in XviD was actually broken and that the alternate curve compression can produce a lot of jumping quantizers which can lead to the rate control overcompensating for big frames and lowering quality.
		In the meantime I have received an updated build which at least in the first SPR scene improves things considerably.
	www.doom9.nl /codec3-4.htm (1065 words)

	Re: [XviD-devel] Adaptive quantisation
		.....ok, I just did some research and have to admit that I'm a bit angry now: uManiac seems to have overwritten my luminance masking code even while stating that the new code is "unoptimized".
		There are such nice things like "#ifdefs" to add experimental new code!
		And no, luminance masking _cannot_ increase quality (as someone over at doom9 asked).
	itdp.de /Xvid-devel/2002-08/msg00023.html (603 words)

	Codec Comparison (Site not responding. Last check: 2007-10-13)
		From my experience with both SBC and DivX4 I can say that SBC normally is very accurate unless you use unsuitable parameters, and DivX4 can be accurate at some times and then suddenly be 10MB off for the next movie.
		In XviD I used the H.263 quantizer, motion search precision 6 and lumi masking during the 2nd pass for the 1 CD rip, and MPEG quantizer, motion search precision 5 and no lumi masking for the 2 CD rip.
		In VP3 I set the bitrate, keyframe interval to 9999 seconds, auto keyframe turned on as well as quick compression.
	www.home.no /doom9esp/codecs.htm (1169 words)

	Doom9 Italia :: Leggi argomento - XviD: lumi masking sì, lumi masking no?
		In passato ho fatto alcuni encode col lumi masking, e il risultato è stato soddisfacente.
		Ora sono alle prese con 'tutto su mia madre'.
		da qui il mio quesito: lumi masking sì, lumi masking no?
	forum.doom9.it /viewtopic.php?t=495 (165 words)

	Lumi Masking (Site not responding. Last check: 2007-10-13)
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	www.mondomacabro.com /lumi-masking.html (278 words)

	March 02 (Site not responding. Last check: 2007-10-13)
		I also tested against DivX4.12, the file was 23MB at the same quality.
		XviD at the same setting using H.263 quantizers returned a 20.5MB file, using lumi masking that went down to 19.7MB and using MPEG quantizers I had a size of 21.7MB.
		Since the clip is rather short I have no fps numbers at this point but I'll try on longer clips.
	www.doom9.cn /old_news/march02.htm (5546 words)

	Home (Site not responding. Last check: 2007-10-13)
		Advanced options--> Just as in picture below (correction: FourCC can be DivX so your friends could watch your movie with their DivX codec installed - no need for them to install XviD codec then).
		In this, new guide version, I decided to activate Lumi Masking.
		Also, Max and Min I-frame you should set to 250 and 1.
	www.inet.hr /~dkokeza/xvid (1056 words)

	Dr. DivX encoding failed (Site not responding. Last check: 2007-10-13)
		Tamper with it too much and you'll just wreck it.
		Oh btw about gamrdev's build, you can actually see the lumi masking work, i encoded about 30secs of something today and instead of seeing blocks (well some) in this scene with the wentieth entury *ox logo next to it in the dark blue clouds, you could it being compressed.
		And after that when things needed compressed they got compressed.
	forums.divx.com /eve/ubb.x/a/tpc/f/401101651/m/512103022/xsl/print_topic (1247 words)

	Nade.dk: Copy Your Dvd To Xvid With Ac3 Surround Sound (Site not responding. Last check: 2007-10-13)
		Same goes for Minimum I-frame interval -- leave it at 1.
		All three checkboxes (Enable lumi masking, Enable grayscale and Enable interlacing) should be unchecked.
		Also, set manually the path for 1st pass stats -- if you don't do this, the 2nd pass wont find your 1st pass' analyzing data and the 1st pass is basically useless.
	nade.dk /web/nade/site.nsf/files/E165FD45C9FEEF8CC1256C8400477FF9 (4223 words)

	XviD Setup Guide
		Press the "Advanced Option" button, and you should see the following screen :
		Enable lumi masking - this is similar to the psychovisual enhancement feature in DivX 5.x, and similar to how MP3 compresses audio by removing data the human ear can't pick up, here, data the human eye can't distinguish is removed.
		Just like psychovisual on DivX 5.x, there may be distortion effects when this is enabled, so don't do it unless you are hard up on space.
	www.rodivx.home.ro /XviDSetupGuide.html (1665 words)

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