Some interesting findings on the 'Shrek' transfer and DVDs resolution in general

Discussion in 'Archived Threads 2001-2004' started by Bjoern Roy, Dec 1, 2001.

  1. Bjoern Roy

    Bjoern Roy Second Unit

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    Here we go.
    Let me clarify my intentions here first. Shrek is a very good transfer. If most of my DVDs had a transfer like Shrek, i would be in heaven. I think Toy Story's is a tad more defined, has better contrast delineation and less ringing. But i would use both to show of my system. Toy Story might also not be the best quality achievable on DVD, but its a bit closer to that limit than Shrek. When Shrek is an A, then the Toy Story's are an A+.
    The intend of my posts are multiple:
    1) Show how much better a DVD could actually be with its 720x480 resolution.
    2) Show that the slight ghosting/ringing on the Shrek DVD isn't 'artistic intend', but an actual flaw, albeit a rather minor one.
    Those of you, who have read some of my posts/reviews, know that in addition to pointing out flaws (like EE etc.), i like to have some kind of a comparison, to demonstrate the issue. E.g. for TPM, i used the R2 disc and the trailer as a reference, to show just how bad the EE in the R1 feature presentation is.
    What makes this analysis of Shrek special, and kind of a milestone, is that i have a couple of highres rendered images for comparison, as a reference! That way, i will not only be able to compare several incarnations of DVD transfers with each other, but rather the DVD transfer to the original rendered frames.
    That way, we have a great opportunity to show 1) from above. What would a DVD image look like, if the content would use the 720x480 pixels to its fullest intend, without any filtering, softening, EE, etc...
    And we can also see, whether the slight ringing/ghosting (in form of halos around bright objects) that can be found in the transfer is there by intend, or a flaw of the transfer. But again, this is from a nitpicking front projection point of view, the ringing in TPM is ten times as pronounced.
    I have several highres pics from Shrek. Some are about ~1700x950 pixels, which is most likely close to the resolution the complete movie was rendered at for the film presentation. Toy Story was rendered at about ~1500x850, if i remember correctly. One picture is in the 3000x2000 dimension, which i doubt was used for the prints, but rather as a show off.
    I always found the Shrek DVD transfer to be slightly to dark/murky. The highres pics on the other hand are slightly too bright. The brightness i saw in the theater (several times, different theaters) was somewhat inbetween, which was more pleasing.
    1. Colors, brightness, framing
    [​IMG]
    You can see that the top picture from the DVD looks kinda murky and pale, while the bottom one might be a tad too bright. It nicely reveals more shadow detail, though.
    Which interpretation of the color scheme is correct? I don't know. The dragon in the lower picture looks a tad too mangenta to me.
    Also note, that the framing is different. For whatever reason, the DVD cuts off some picture content at all 4 sides. Especially noticable at the top and bottom. For what its worth, the Pan and Scan version does have the full vertical information of the bottom picture, but looses some more at the sides. As if they were trying to emulate Super35 transfers?
    2. Dragon
    Highres image size ~1700x950.
    [​IMG]
    This is a crop from the highres picture. Lots of detail, amazing.
    [​IMG][​IMG]
    The left is the highres pictures downsampled to 720x480, emulating a perfect DVD transfer. I reduced color information, to emulate 4:2:0 encoding. The crop on the right is the DVD still. Both frame crops are zoomed 3 fold to see the difference better and match the size of the highres crop.
    Look at how soft and blurry the DVD frame is. It isn't using the potential of the 720x480 resolution at all. Especially in the vertical dimension. Consider the left to be the upper limit of what a DVD could possibly look like. I often complain about DVD transfers being filtered to reduce entropy (for less encoding artefacts at same bitrate) or to reduce interlace flicking. But never before have i been able to show you guys exactly what we are missing, because i didn't have a reference to compare the DVD capture to. Here you have it.
    While the downsampled 720x480 frame on the left is less detailed than the original above, it still is perfectly in focus and uses the resolution to its fullest.
    The other thing to note here, is the ringing. Take a look at the middle horn. In the original and the downsampled picture, its well defined. In the DVD, it has a bright halo around it (above and below). This ringing/ghosting effect can be seen throughout the DVD. Sometimes it simply looks like ordinary EE, at other times, it seems like bright areas seem to resonate/glow into the suroundings, which is a bit different than EE, because the corresponding dark halo is missing. Its definitely not by intend, though, since it doen't show up in any of my original pics. I will post more examples of later.
    As you can see in the next round, there IS an actual intentional 'glow' effect used in some scenes, but it looks different from the effect discribed here.
    continued...
     
  2. Bjoern Roy

    Bjoern Roy Second Unit

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    2. Fiona
    Highres image size ~1700x950.
    [​IMG]
    This is a crop from the original highres picture. Again, amazing detail.
    [​IMG][​IMG]
    Same comment as before. Downsampled 720x480 image on the left nice and detailed, DVD blurry. Look for example at the imprint on the yellow thing on her shoulder.
    This picture actually shows the intentional 'glow' filter, the renderer used in a few selected scenes. Take a look at the glow of the highlight on her shoulder. Its easy to differenciate from the ringing, though, since it actually looks like a natural glow, with a smooth fall-off and everything.
    If you look very closely at the right edge of Fiona's face in the DVD frame, you will see a slight bright halo to the right of the edge (especially in the hairs) and a slight darker halo a few pixels inside her face. This looks like conventional EE. This effect is not on the original frame. Its not easy to spot here, i will post picture were the effect is several times as pronounced.
    continued...
     
  3. Bjoern Roy

    Bjoern Roy Second Unit

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    3. Farquad
    Highres image size ~3000x2000
    [​IMG]
    The left is the DVD crop, the right is the full resolution picture. As i said, probably not even the film prints had this incerdible amount of detail.
    The image shows the EE slightly better. Look at the face edge. In the DVD, the edge has a bright halo to the right and a dark halo in the face. Its not in the original.
    4. Compression artefact?
    And before someone starts with the bitrate and compression nonsense again, let me make this clear. The ringing/ghosting is NOT caused by low bitrate, is NOT an mpeg artefact and would NOT have been avoided if the movie didn't have any extras on the disc.
    Here is the downsampled 720x480 frame and the DVD again:
    [​IMG][​IMG]
    And this is what the downsampled 720x480 frame would have looked like with a non optimal bitrate:
    [​IMG]
    This is with even lower bitrate, thus higher compression:
    [​IMG]
    This is with ultra low bitrate:
    [​IMG]
    The only thing that gets worse is MPEG blocking artefacts and overall definition. But NON of the deficiencies of the DVD transfer show up.
    (I decided to post a thorough bitrate fetishism rant here [​IMG])
    Thats it for now. Pictures that show the ringing and ghosting much more pronounced yet to come.
    Again, the main point here is not to show how terrible the Shrek transfer is, but rather to show how much more potential there is within the resolution limit of the DVD format.
    Best regards
    Bjoern
     
  4. Matt Heebner

    Matt Heebner Stunt Coordinator

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    Is it possible, and please forgive me if I sound ignorant with this question, that the engineers(or who ever it is that transfers movies to DVD's) just have not learned how or perfected the transfer process yet?

    For example, when the original Playstation came out, there is an obvious difference in first gen. games as opposed to third or fourth gen. games. I have read that many game developers learned over the course of years how to make games so much better looking and running by just hammering on the playstation. I even read that some developers were constantly surprised by what they could make the playstation do with software, but that it took them literally years to figure out how to do it.

    Could it be that as the technology gets older, the engineers will find new and better ways of transferring movies onto DVD. (Aren't HD mastered transfers newer than how they were transfered when the format first came out?)

    Again, I am sorry if this is a stupid question to someone who knows how this is done. I really only just read about how movies are transfered in the new issue of Stereophile Guide To Home Theater as the talked about doing Pearl Harbor.

    Matt
     
  5. RobertR

    RobertR Lead Actor

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    Bjoern, as usual, no one analyzes and explores DVD audio and video better than you! And you use clear technical objective means to do so. Excellent work.
     
  6. Mark Turetsky

    Mark Turetsky Supporting Actor

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    Where did you get those amazing stills and where can I find them?
     
  7. Dwight Amato

    Dwight Amato Stunt Coordinator

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    Sorry to dig up such an old thread. Before posting my thoughts on Shrek I thought I would do some searching through past posts. I totally agree Bjoern regarding the ringing issues. I have a Panny 47" HDTV and I have been constantly bothered by what looking like EE to me. I finally was able to disable all image enhancing effects from my tv today. Immediately I grab Shrek and look forward to having the perfect picure with no EE that read about at all the sites. What did I see? Less EE, but it's still there. What blows my mind is that EVERYONE thinks this is the best transfer ever! Hell, Deuce Bigalow looks better in that it has no EE that I can see.

    I have no idea why Dreamworks distorted what could have been the most perfect transfer ever. I'm just glad that I'm not the only one to see it.
     
  8. Patrick McCart

    Patrick McCart Lead Actor

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    What exactly is the comparison?

    MPEG-II and high-res stills are two very different things.

    It would be like comparing a strip of 35mm film with its DVD counterpart. Obviously, the 35mm will look better since it's the full resolution. DVD is just a downscale coversion for your TV.

    You won't see ringing go away until a system is developed that can keep the exact resolution of film.

    Shrek had to be downscaled to NTSC res since it was rendered for 35mm.
     
  9. Bjoern Roy

    Bjoern Roy Second Unit

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    Patrick,
    maybe you should actually read my posts before you throw in your comments?
    No kidding. And thats exactly why i ALSO downsampled the pictures to NTSC DVD resolution for comparison.
    Bjoern
     
  10. Kyle McKnight

    Kyle McKnight Cinematographer

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    Wow, I'd love to get my hard drive on some of those High-Res pics in full, especially the 3000x2000 one.
     
  11. Kami

    Kami Screenwriter

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    Excellent analysis, Bjoern. Now only if some major studio had you hired as a compressionist, we'd be set!
     
  12. Shayne Lebrun

    Shayne Lebrun Screenwriter

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  13. Patrick McCart

    Patrick McCart Lead Actor

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    Never mind..

    I had the two switched (aixelsyd?)
     
  14. Ricardo C

    Ricardo C Producer

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    Nevermind.
     
  15. Michael Bailey

    Michael Bailey Stunt Coordinator

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    Excellent analysis Bjoern. I knew Shrek was not the best animated transfer I had seen but had no idea why. Say, how does Shrek stack up against an animated transfer that I thought was excellent such as Dinosaur? Anyone feel free to answer but I would hope Bjoern includes his opinion as well.
     
  16. Dwight Amato

    Dwight Amato Stunt Coordinator

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    I have always gone against what the reviewers say about Dreamworkds animated titles. While the movies are excellent, the picture to me is not. I thought this way back when Antz came out; A Bug's Life was much better to me (although not 16x9 enhanced).

    To me, all of the Disney animated movies are much better then the Dreamworks counterpart. I cannot talk about downsampling issues, but on my display I see much less EE on every Disney title.
     
  17. Ken_McAlinden

    Ken_McAlinden Producer
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    If you listen to the commentary on Antz, the directors talk about how they applied a lot of analog post-processing to the digital images (cheesecloth effects and such) to get the look they were trying to achieve. This was brought up again in interviews after Pixar and Disney started doing their direct digital transfers when they were asked why they did not do a direct digital Antz transfer. I wonder if they applied some similar effects in the digital realm to create the final versions of Shrek for DVD and for digital projection. This would certainly not explain all of the artifacts that Bjoern has detailed, but it could explain some of them.
    It does look like they filtered the image to reduce entropy/improve compression and then applied mild EE (effectively increasing entropy with ringing noise) when the result looked too soft. Whether this was done on purpose or is an encoder artifact is way beyond my knowledge level. [​IMG]
    Regards,
     
  18. mark_d

    mark_d Second Unit

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    I appreciate that the images are well blown up, but your "optimum" shots look overly blocky to my eyes. I would have thought that the softer DVD version would look more appealing on a rig as awsome and finely honed as yours.

    Brightness issues and halos aside, I think the DVD original of Fiona's face is the more pleasing compromise.

    Mark
     

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