I think, that when lpowell posted this "Basically, what my recommended pedestal adjustment does is crush the noise and artifact-contaminated bottom end of the sensor's range into solid black..." That it means he's saying now that the artifacts have nothing to do with the interpretation of the footage by the application, and/or a result of the GH2 producing RGB values under 16 (it doesn't). Which is contrary to what he initially said, and its what he initially said that made me question his premise.

Also, his description of what the pedestal adjustment is doing "The luma components that lie just above that threshold are legitimate image details and the pedestal adjustment fades them gradually, rather than raggedly, into black." Isn't true, its basically clamping (shifting your whole range) which is, to me, while being a valid approach, is not the best approach to take for dealing with those kind of artifacts. There is nothing 'gradual' going on. You don't want to shift your entire range to fix blocking artifacts. There is nothing gradual about a pedestal adjustment, it seems to me to be no different to the old analog video days of turning the knob on the luminance black level of a proc amp. Matching footage from the same shoot that you don't make a pedestal adjustment on, because there are no dark blacks, or artifacts within them, will be a PITA. Adjusting the gamma post pedestal adjustment as he recommends will not help this, as that can create even more problems now that the range has been dropped.

@DrDave

"Sending material through intermediate codes like cineform, prores, etc proves nothing"

Correct. My first example referred to direct import of the actual MTS file into Avid (without conversion prior to import). I've then used 4 other softwares to illustrate that the respective files of all those 4 softwares show exactly the same levels as Avid, regardless of the codec used. (And exactly the same levels as the GH2 itself on the RGB histo in playback mode.)

Look, it's very easy. Some simply see a "strange" behaviour of the GH2 while shooting video (histo-squeezing / LCD with crushed blacks + whites / RGB histo in playback mode does not show the full range of levels from 0-255, while it does in photo mode, of course). But for some the GH2's behaviour makes sense as they see exactly the same levels in their editing software (in other words: consistent levels from shooting to editing). Choose whatever you prefer ...

I thought this was the thread for FlowMotion settings ?

@LPowell

"Since you've sunk to the level of personally insulting and trolling me, I consider your further interest in this topic as nothing more than inflammatory provocation"

it is of course very easy to stop the dispute this way. naturally it would have been much harder for you to openly admit a mistake. So be it…

@towi Since you've sunk to the level of personally insulting and trolling me, I consider your further interest in this topic as nothing more than inflammatory provocation.

In fairness guys, this heated discussion is a really good demonstration about why studio levels suck suck suck. I guarantee you that a massive amount of people working in video don't fully understand all the implications, or exactly how their software handles it - even if they think they do. It's not because we're stupid, but because the whole issue is absurdly complex.

I have programmed my own effect for Premiere, so I know a little about how it works there. From an effect's point of view, it can request the pixel format(s) it wants to work in. Some formats are full swing, some in studio levels (all documented). Premiere will internally convert the frame to the most suitable format the effect supports before handing it to it (and convert it again if needed for other effects, display or exporting). It presumably picks formats that will require the least damaging conversions.

So it's the effect's job to handle these formats correctly. If it performs gamma correction with a studio-levels format, it needs to handle that correctly. However I would then expect it to assume the blacklevel is 16 - so if there are useable super blacks (or whites) you want to preserve correctly, that does require manual intervention (if you care).

What I'm also not 100% sure about is how Premiere imports the footage. Logically (and I'm pretty confident this is what actually happens), Premiere will important studio level footage as-is. This is because (as ways pointed out), super-blacks and whites are part of the standard, and so should be preserved. So it makes no sense for any NLE to clip anything off unless it has to convert to full-swing 8bit RGB at some point.

And with Premiere that can happen in unintuitive ways - if you have any effect on your clip that only supports 8bit RGB, then Premiere has to expand the studio range (and clip off the supers) while the frame is being processed. So to avoid that, stick to YUV or float capable effects.

Finally, just because there seem to be clear rules of how formats are handled, doesn't guarantee they always are correctly. For example, there seems to be a known issue where some versions of Premiere import some rec709 footage as rec601 - that's a different issue (it just means that the colour & gamma are slightly off), but the point is that bugs exist everywhere, and even if many codecs import exactly as advertised, there might be the odd bug in a specific file format. So it's all a minefield really.

Bottom line, kill off studio levels & interlacing and this whole legacy mess goes away. That will probably take many years though (sigh), especially while new cameras are still coming out with interlaced video modes (WTF?).

@towi "This is what you call "hard evidence"?"

Yes, and like many who insist on maintaining standards that have outlived their former usefulness, you're determined to reject it with as much disrespect as you can muster. Since you've nothing but insults to offer at this point, I'll take that as confirmation that Avid does indeed work exclusively in Studio Swing's broadcast-restricted color space.

@LPowell - "That's correct, is it not? Is it not true that Avid's internal black level is always set to 7.5 IRE?"

@towi - "NO, NOT TRUE ..."

@towi "...Avid's INTERFACE black is at 16 Y'. Likewise Avid's Title tool will create blacks at 16 Y' and whites at 235 Y'. Too, if you add a blank space in a sequence (timeline) it will be at 16 Y'."

When I refer to Avid's internal black level, I'm not talking about its file import options. What concerns me is that regardless of how you choose to import your files, Avid operates with its black level set to 7.5 IRE (i.e. 16 Y'). The examples you noted above confirm that 7.5 IRE is in fact Avid's fixed black level (and there is no option to set Avid's internal black level to 0 IRE). Here's a link from Avid's Knowledge Base that confirms that this is the way Avid is designed to work:

http://avid.custkb.com/avid/app/selfservice/search.jsp?DocId=216429&ssdFilterCommunity10=368&ssdFilter_SearchKeyWord={0}%2Cpinnacle+site%3Awww.avid.com%2FUS%2Fsupport%2Ftraining&Hilite={0}%2Cpinnacle+site%3Awww.avid.com%2FUS%2Fsupport%2Ftraining

Your attempts to obfuscate this basic fact with diversions into QuickTime, NeoScene and 5DtoRGB transcoded workflows are irrelevant. And what you apparently fail to understand about After Effects is that it provides comprehensive Color Manangement options via ICC Profiles that control not only file import, but the reference levels of its internal color space as well. From among numerous built-in profiles, this enables you to select whether each project operates in either of these two standardized color spaces:

• Rec. 709 Studio Swing (16-235) Black Level: 7.5 IRE
• Rec. 709 Full Swing (0-255) Black Level: 0 IRE

Depending on which profile you assign to each project, After Effects will import video files into that selected color space based on the color space profile that is embedded in each file. If the file's profile matches the project's profile, it will be imported without remapping its color space. With GH2 MTS files, that is what happens when you select Rec. 709 Full Swing as the project profile. If you instead select Rec. 709 Studio Swing as the project profile, AE will detect that the file's color space doesn't match, and will remap it into the Studio Swing color space.

Below are examples of the color spaces that After Effects uses in Studio Swing and Full Swing Profiles. Note that if the MTS file's embedded profile (Rec. 709 Full Swing) had been incorrectly identified by After Effects, the file imports would not have produced the correct 16-235 waveform in Studio Swing and the correct 0-255 waveform in Full Swing color spaces.

@LPowell

"That's correct, is it not? Is it not true that Avid's internal black level is always set to 7.5 IRE?"

NO, NOT TRUE ... as I've said numerous times in this thread. I've posted the quoted PDF to make this very clear: Avid's import setting "rec709" simply means: "no remapping applied". (Avid EXPECTS legal rec709 footage... this is why the "rec709" import settings means: "do nothing, the footage is ok").

Page 1 of the quoted PDF:

"I’d recommend reading the ‘RGB’ and ‘601/709’ options as follows:

IMPORT:

• RGB: Remap 0-255 levels over 16-235 video (blacks lifted, whites reduced)

• 601/709: Do not remap (keep levels as they are)"

Avid's INTERFACE black is at 16 Y'. Likewise Avid's Title tool will create blacks at 16 Y' and whites at 235 Y'. Too, if you add a blank space in a sequence (timeline) it will be at 16 Y'. But if you import a file containing 0-255 Y' levels Avid will show all the 256 levels of the original file. See attachment (on the left a JPEG containing a ramp from 0-255 imported with said "rec709" setting).

@towi As your histograms indicate, you've chosen a largely gray frame that contains virtually no white or black luma components. This doesn't prove your point since there's nothing to display anywhere close to 235.

In addition, much of your workflow is relying on QuickTime and/or ProRes conversions that could also introduce Rec. 709 color space remapping. At any rate, the DNxHD, H.264, and ProRes frame grabs you posted are not direct evidence of the contents of the original MTS file, they are transcoded renderings!

According to this article, Avid continues to work in a Studio Swing 16-235 color space, even if you choose to bypass its automatic color space conversion:

http://terburg.home.xs4all.nl/Publications/601_709_RGB.pdf

"Note that the Avid is a video editing application, and is supposed to work in video color space (601/709). So the Avid codec always assumes you are going to end up with something that is supposed to be 601/709 compliant (ergo 16-235)."

That's correct, is it not? Is it not true that Avid's internal black level is always set to 7.5 IRE?

@LPowell

"please download the MTS file that I posted last week at the top of this page, it contains the smoking gun you're looking for"

Just registered at Vimeo to finally look at your file.

• First attachment shows the MTS file imported into Avid while preserving the original levels (without any remapping - please note once and forever: Avid does not apply any "under the hood" remapping unless you explicitly choose to do so)

• Second attachment shows the MTS file converted through "Media Converter" (which utilizes FFmpeg) to QT DNxHD. Imported into Avid without remapping levels

• Third attachment shows the MTS file re-wrapped through ClipWrap to QT H.264 and opened via "AMA" in Avid ... the attachment shows the import menu (prior to actually importing the file) and the source file's histo (vertical bold lines show 16-235 Y' range)

• Fourth attachment shows the MTS file converted through 5DtoRGB ("luminance range" set to "full range" to maintain all the levels that live within 0-255) to ProRes HQ and opened via "AMA" in Avid ... the attachment shows the import menu (prior to actually importing the file) and the source file's histo (vertical bold lines show 16-235 Y' range)

• Fifth attachment shows the MTS file converted through Cineform "NeoScene" to CFHD and opened via "AMA" in Avid ... the attachment shows the import menu (prior to actually importing the file) and the source file's histo (vertical bold lines show 16-235 Y' range)

@Sidhho To my knowledge, NLE's will not expand Studio Swing 16-235 streams into Full Swing 0-255. The behind-the-scenes conversions always produce Studio Swing streams, not the reverse.

Contrary to what @towi claims (and has yet to provide any tangible evidence to back up), the GH2's histogram displays are not literally recorded into the MTS files. While intuitively appealing, this speculation is disproven by examing the range of the luma signals encoded in the files. If you'd like to see for yourself, please download the MTS file I linked at the top of this page. While the GH2 does use Rec. 709 color primaries (i.e sRGB), it encodes Full Swing luma components, much like Canon and other DSLR's.

As I've pointed out to @towi, as long as you remain within the default Studio Space environments of Avid and Vegas editors, your files will be automatically converted into its 16-235 range, regardless of what they originally contained. If this is what you prefer, and you like the results it produces, you can choose to remain safely within that NTSC broadcast-constrained world.