Personal View site logo
GH2 and ITU 709
  • 68 Replies sorted by
  • @mozes You are correct regarding Sony Vegas, although there is one important difference:

    The main application window's preview window (one on timeline page) appears to always be at 0-255. The preview device settings for preview monitor (full screen) allow you to select 16-235 for different display adapters.

    I'm not sure why the small timeline preview only displays 0-255. Fucking strange, but I'm used to its quirks.

    Here's a piece of info that may be helpful, although we would need to look closer to the Vegas encode settings for Windows media video (wmv files):

    If you drop a GH2 video on the vegas timeline (do NOTHING else) and export with default Vegas wmv settings, the video is washed out. This certainly would imply the original video is 16-235. As you know, wmv files are 0-255.

    If you apply the "Studio to Computer" (as you stated), the image looks proper for back and white levels.

  • @proaudio4, i have also set my pc monitor to a srgb profile in my videocard settings.
    left preview screen vegas, right my second window activated thru vegas

    Naamloos.png
    810 x 978 - 294K
    Naamloos.png
    2640 x 1024 - 3M
  • @DirkVoorhoeve

    -> "towi Why not assume it is not remapping at all, but just converting from the sensor's RGB values directly to the studio-swing Y'CbCr colorspace?"

    -> "Because I don't know of a "studio swing Y'CbCr color space". I only know of "Y'CbCr" which basically includes 256 luminance levels (talking 8bit). IMHO the term "studio swing" only refers to the levels utilized for image content ("broadcast save colors") and has nothing to do with a "color space" in the first place"

    -> "Why not assume it is not remapping at all, but just converting from the sensor's RGB values directly to studio-swing Y'CbCr image content?"

    -> "to do so the camera software has to apply a tone curve"

    -> "which of course it would not have to do when converting to full-swing Y'CbCr?"

    I would say so, yes. If you convert a fullswing RGB video to fullswing Y'CbCr you don't have to apply a tone curve (actually it's just a color space conversion). But if you want to make a studio swing Y'CbCr video out of a fullswing RGB video you have to compress the levels.

    I guess the GH2's banding issue comes from the compression of the levels and apparently the GH2's software applies the tone curve quite late in the image processing pipeline ... as the banding looks like typical 8bit posterization.

  • proaudio4, my experience in Vegas 10 matches yours: the in-window preview is showing the full range of levels 0-255, and only in a full-screen video can I see the 16-235 levels expanded to show black and white properly.

    I think the WMV export problem you see is peculiar to WMV. I don't see any such problem when rendering with Mainconcept MPEG-2 or MP4.

  • @balazer Interesting... Maybe an export setting for window media video.

    @mozes Hmmm.... It certainly appears you have the same levels. Well done man. I have a Radeon AMD card too... I'll have to give that a go.

  • I gave up on wmv years ago because of the levels shift when exporting. It's not alone, there are others as well.

  • @proaudio4 calibrating my second monitor (a LCD TV) was a real challenge,
    The catalyst control center have a lot off options, and it did take a lot off time to set it good.
    The LCD TV is connected throe the hdmi out from the radeon card.

  • @towi to get full swing Y'CbCr, doesn't the camera also have to apply a tone curve (2.2 instead of 2.4, or is gamma a completely different thing?)

  • @DirkVoorhoeve

    The gamma does not affect the actual black and/or white level (neither on still images nor on video images nor on viewing hardware... monitors that is). The gamma only affetcs the "TRC" ("tonal value reproduction curve"). I don't know anything about the GH2's image processing pipeline... but basically the camera software has to translate the RAW data of the sensor into "some" image format. I guess first the "picture style" (photo/JPEG) or the "film mode" (video/MTS) settings apply certain TRC's (so in video mode the "standard", "cinema", "smooth" etc. settings). But these TRC's are more complex than a simple "gamma" curve.

  • What a brain teasing topic. My brain is gonna burst.

    I got the latest 5dtorgb tool. It has a few options to choose. Decoding Matrix is obviously REC.709. Then there’s Luminance Range option. After reading all replies in this thread, I think the correct setting would be “Full range” instead of “Broadcast range” because GH2’s in-body processing already captured the data in the broadcast range (16-235). Therefore “Full range” option would not alter the captured data’s 16-235 range. Am I correct?

  • cool. thanks @towi!

  • My experience is a bit different. The preview window with the tiemline on Vegas Pro 10 is clearly 16-235 with GH2 AVCHD native footage. I apply levels to convert to computer RGB when editing and grading on the computer momitor. The method I then use for export is this one: http://www.jazzythedog.com/testing/DNxHD/HD-Guide.aspx I remove the computer levels and the timeline reverts to 16-235. I render the timeline to DNxHD 145 8bit 1080p and then run it through Handbrake at 720p according to the method and settings at jazzythedog. I then upload to Youtube or Vimeo and the levels are corrrect. I have tested this process with test charts as well. It has proven to work well for me. Yes, Vegas does have some quirks, but I like it overall. And it handles the GH2 footage well in native form.

  • @bt, why not just change the scopes setting to 0-255 during editing??

  • In Vegas Pro, merely changing the scopes doesn't change the preview; thus, it's washed out in 16-235. That's why I change the levels efx to computer rgb. I use the scopes, but I leave them unchecked, or default, which shows me exactly what's on the timeline and what the levels are. I switch back to 16-235 for render and output because Youtube and Vimeo will rescale the clip levels to 0-255. If you leave it in 0-255 for output to Vimeo and Youtube, the blacks will be crushed and the whites clipped.

  • I'm referring to my own use in Vegas Pro 10. I'm not familiar enough with recent versions of Avid and Final Cut.

  • Yes I know the preview dosn't change, but I assumed you were editng levels only using the scopes as the first step in your workflow in Vegas, that is what I do.

  • I'm big on scopes, so I do have the scopes open constantly. So I'm looking at both the look of the footage in preview as well as checking the scope levels for blacks and whites. I just added a second monitor for preview only. It really makes it nice for editing and opens up some real estate on the main screen.