Frank
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It's fascinating that Columbia/Tristar applies edge enhancement to 2.35:1 DVDs only. I would like to know why they do it.
Frank
Frank
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My 'Ultimate Guide to Edge Enhancement' (with lots of pics) (1 Viewer)
- Thread starter Bjoern Roy
- Start date
Agee Bassett
Supporting Actor
- Joined
- Feb 13, 2001
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- 922
Agee,
sure, as long as you give me credit and point me to any discussion that arrises so that i can answer questions, go ahead.
Regards
Bjoern
Consider it done.
------------------
Oliver Twist - BFI #46.
"Cinema is simply letting the audience fill in the blanks." - David Lean.
pic courtesy of Steve Matto
Dave Barth
Stunt Coordinator
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- Jul 21, 2000
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- 230
Thank you for your informative web page. I've always wondered what people meant by edge enhancement. The examples you give are very concrete. I appreciate your attention to detail and I hope we all see fewer and fewer transfers plagued by excessive (=any?) EE.
I also hope that one day I own a home theater setup where I can see EE
I also hope that one day I own a home theater setup where I can see EE
Hakan Powers
Stunt Coordinator
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- Mar 13, 1999
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- 244
Very good and informative article Bjoern. Kudos for a job very well done !!
Gary King
Second Unit
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- Apr 13, 1999
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- 479
I have a question...in the article it mentions that a low pass filter is used to eliminate flickering. I dont understand how there could be flickering.
I mean, if youre watching an NTSC movie at 29.997 frames per second, then theres only going to be as much flicker as the video signal allows, how can a video signal have more or less flicker?
The problem isn't strictly related to the frame rate (temporal domain), but is actually a result of the interactions of the spatial domain (image) with the temporal domain.
Photographs (or, in this case, film frames) have significantly higher resolution than a DVD supports, so any video stream will need to be resampled before it is stored on disc. Unfortunately, a byproduct of this resampling process is that artifacts appear in the resampled image that were not in the original image (you might be familiar with the term aliasing, or jaggies, mentioned in conjunction with video games -- this is exactly the same).
Compounding this problem, if I were to take two photographs of the same scene from slightly different positions (e.g., panning), then the artifacts that are introduced when I resample the second image *will not* be the same as the artifacts introduced in the first image. As a result, small details (e.g., blades of grass) that were present in the first image will be absent in the second image, replaced by other objects. If I were to continue my pan across the scene, objects might strobe profusely, and you would have a splitting headache after a few seconds, regardless of whether you are watching at 24, 29.97, or 400 frames/second.
So, one way to remove this strobing is to modify your resampling process, so that extremely high-frequency information in the original image does not carry over to the new image. Low-pass filtering the signal effectively does just that; however, a low-pass filtered image will look blurrier and less detailed than an unfiltered image.
So, in short... filtering of some sort is necessary when films are transferred to DVD, or else you will get some nasty jaggy and flicker artifacts that weren't present on the negative.
I mean, if youre watching an NTSC movie at 29.997 frames per second, then theres only going to be as much flicker as the video signal allows, how can a video signal have more or less flicker?
The problem isn't strictly related to the frame rate (temporal domain), but is actually a result of the interactions of the spatial domain (image) with the temporal domain.
Photographs (or, in this case, film frames) have significantly higher resolution than a DVD supports, so any video stream will need to be resampled before it is stored on disc. Unfortunately, a byproduct of this resampling process is that artifacts appear in the resampled image that were not in the original image (you might be familiar with the term aliasing, or jaggies, mentioned in conjunction with video games -- this is exactly the same).
Compounding this problem, if I were to take two photographs of the same scene from slightly different positions (e.g., panning), then the artifacts that are introduced when I resample the second image *will not* be the same as the artifacts introduced in the first image. As a result, small details (e.g., blades of grass) that were present in the first image will be absent in the second image, replaced by other objects. If I were to continue my pan across the scene, objects might strobe profusely, and you would have a splitting headache after a few seconds, regardless of whether you are watching at 24, 29.97, or 400 frames/second.
So, one way to remove this strobing is to modify your resampling process, so that extremely high-frequency information in the original image does not carry over to the new image. Low-pass filtering the signal effectively does just that; however, a low-pass filtered image will look blurrier and less detailed than an unfiltered image.
So, in short... filtering of some sort is necessary when films are transferred to DVD, or else you will get some nasty jaggy and flicker artifacts that weren't present on the negative.
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