[Gamma mismatch between JP and US BD releases]

[Qyot27]

[MOD258: Hijacked OP, the following text is by mirkosp; original post at the bottom, under spoiler.]

So, after checking around, I have come to the conclusion that most if not all US BD releases are likely to have a mismatching gamma compared to the original JP BD release.
What this means is that you should apply the following avisynth code to attempt to restore the correct gamma values, when dealing with such a source:

Code: Select all

levels(0,0.88,255,0,255)

This way you will invert the error and get to the correct colors.
If you want a higher quality result, you can use LaTo's SmoothLevels, part of SmoothAdjust, instead:

Code: Select all

smoothlevels(gamma=0.88)

Here follows a list, in alphabetical order, of certainly wrong releases, with a luma that requires correcting:

• Cowboy Bebop (UK release by Anime Limited)
• Full Metal Alchemist: Brootherhoods (by Funimation Entertainment)
• K-On! Season 2 (by Sentai Filmworks)
• Serial Experiments Lain (by Funimation Entertainment)
• Shakugan no Shana III: Final (by Funimation Entertainment)
• Towa no Quon (by Sentai Filmworks)

This list is by no means extensive, as further comparisons need to be done between US and JP releases to be certain, however the releases we have checked so far are from different editors and have very different release dates, which suggests this is a common practice.
So far all known compared sources do present the difference, so I currently would suggest to correct if in doubt.
If any source which is identical to the JP release is found, it will be added to a whitelist here, but currently no compared source was matching (not that I know of).
If you can contribute to further test and expand, it would be helpful!

Spoiler :

The comparison shots at the end of the article:
http://konfan.blogspot.com/2012/06/k-on ... eview.html

As the article notes, the Sentai release is rather noticeably brighter than the original. While I've already figured out more or less how to handle this by comparing histograms (if I have screenshots of the original to judge against, anyway), I would like to know if this sort of thing is common with their other releases. Or for that matter, the Blu-ray releases of other American licensors.

[mirkosp]

I recall this happening in Funi's FMA Brotherhood too but I can be damned if I can find the blog which had the comparison anymore. I'm not sure if it is still done on Funi releases, but apparently the reasoning was a different gamma in old american vs old japanese TVs. Quite a dumb reason if that was true, since BDs are supposedly getting watched on HDTVs to boot, making those differences irrelevant.

EDIT: http://web.archive.org/web/201005181629 ... n-blu-ray/

Found it.

[Qyot27]

At least from how I understand that, it looks like if I'm going to see a difference in gamma between the Japanese and US releases, it's more than likely going to be that same 10% deal. So it looks like the K-ON!! situation is identical - the number to give to YLevels was 0.900 which made the resultant image match the Japanese release almost exactly. The result of comparing the histogram shift between JP and US screenshots also resulted in a result that'd be close to 0.900, give or take some hundredths or thousandths.

Taking the FMA screenshot used to illustrate it for that release, the math produced something like 0.914, all things considered about the possible inaccuracies of having to find similar structures in a histogram to measure the shift (the result isn't as close as the K-ON!! example either; even using 0.900, the flower things in the background have still have a fairly big difference, even if everything else seems to be a lot closer to the JP screenshot).

Agreed that it's really really stupid to do that nowadays, but at least it seems to be more predictable than what I feared the case might be. I was almost expecting the issue to be worse and the shift to be variable.

It'd still be nice to have a running list of releases that have this issue, unless it's so ridiculously common that it should just be automatically assumed.

[EkaCoralian]

I think they did the same thing with the Xam'd: Lost Memories BD releases from Sentai. Those BDs are incredibly vibrant.
It's probably a recurring thing for Sentai's BD releases.

[mirkosp]

http://screenshotcomparison.com/comparison/3122

Happens on Lain too.
I'm keen to say it should be considered the default approach at this point... derp.

[Qyot27]

Even though the basic question was Blu-ray, was/should this also be considered a factor for DVDs? I certainly don't remember seeing this kind of obvious difference on those, but I suppose the resolution and color constraints might've had something to do with that.

Or, you know, that my usual DVD player is hooked up to a 13" convex CRT TV and not an HDTV (and I have the brightness set below median on most of the displays I actually use; there are simply scenarios - the family TV - that I can't do this on). So it's fully possible the issue was always there, but I never really noticed because my own visual preferences make it more difficult to see.

[mirkosp]

I wouldn't know since I never actually got around to compare US DVDs to JP DVDs (never had to import US DVDs, but with BDs the situation has changed a bit for me). But on a hunch, I'd say yes, it prolly happened with DVDs, too.

[EkaCoralian]

I've got Clannad DVDs from Sentai, and those are really clear and fairly bright, but I couldn't really give you a comparison between the original Japanese and the Sentai release. I wouldn't be surprised if they upscaled a little bit though.

[mirkosp]

Unlocking and bumping, I think it would be a good idea to sticky this and keep it as a running list of known sources with colour mismatch issues between US and JP release. In fact, I just did that.
I also think we can currently consider all US sources as mismatching unless proven otherwise, since that seems the most common situation.

Adding Shana Final to the mismatching brightness list:
http://www.mania.com/aodvb/showpost.php ... ostcount=8
Funi's release is brighter and it arguably looks like it somehow went through a wrong colormatrix conversion, but that might just be due to how the screenshots were taken (so I think the colours themselves are a human error on the screenshot side); it still doesn't leave a doubt about the brightness issue, though.

[mirkosp]

Apparently, the UK release of Cowboy Bebop has this brightness mismatch as well:
http://www.bulletsnbabesdvd.com/forums/ ... d2#p168990

Funimation is going to release the CBBB BDs coming 2014, and I'm going to assume it'll feature pretty much the same discs as the UK version, barring things like bumpers and trailers, so it's most likely the US BDs will have the issue as well. We'll have to see once they're out, but for the time being I'm going to add the UK release in the list.

EDIT: After inquiring knowledgeble people and investigating some more, I found out that this is all is due to a bug in Quick Time (because we all know Apple's the best when it comes to video, right? ).
The gamma mismatch can be fixed by applying a gamma boost depending on the software; I got the 0.88 value through this article. In avisynth, applying 0.88 with levels' gamma parameter, or, better yet, smoothlevels' gamma parameter, will give out results identical to the source.