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Old August 7th, 2004, 01:34 AM   #1
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Resolution loss in frame mode?

Whats the approx. persentage of resolution loss on the DVC30 and or the GS400 when they are in 30 fps (frame mode)? I'm not concerened about 16:9 or cinegamma, as I can get a similar gamma look in post.

Is it comparable to the 25% loss of resolution on the Canon's in frame mode?
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Old August 7th, 2004, 01:53 AM   #2
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You could ask Panasonic Technical. They should know. I have yet to get a straight answer about Pana's frame mode but Pana has claimed that resolution is increased.
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Old August 7th, 2004, 07:51 AM   #3
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Vertical resolution loss in frame mode is 25%. There is a pervasive article on this site by Steve Mullen on frame mode, progressive scan and interlaced scan that explains this very well.
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Old August 7th, 2004, 08:56 AM   #4
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Guy is correct about the loss in vertical resolution and definitely give Steve Mullen's article a look.

Quote:
I'm not concerened about 16:9 or cinegamma, as I can get a similar gamma look in post.
Why not just use the in-camera cine-like gamma?
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Old August 7th, 2004, 12:08 PM   #5
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Tommy,
It seems this question gets asked a lot. I checked the DVX100 board and they don't have it stickied. Maybe it should be a Notice so folks have access to it before asking the question. The article is available as a reference on Panasonic's DVX100A catalog page.
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Old August 10th, 2004, 03:50 PM   #6
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<<<-- Originally posted by Tommy Haupfear : Guy is correct about the loss in vertical resolution and definitely give Steve Mullen's article a look.



Why not just use the in-camera cine-like gamma? -->>>

Personally, I prefer adding 'effects' in post. I am going to play with the cine-like gamma on the GS400, but I think keeping everything as pristine as possible on the tape is the way to go, and mess with it in post.
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Old August 11th, 2004, 10:20 AM   #7
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Ok, I have to say - no resolution loss in GS400 FRAME mode. At the least in PAL GS400.
Take a look:
Interlace mode 4:3
FRAME mode 4:3

Two words about PRO-CINEMA. No way to restore information in an overexposed area in postproduction. I use PRO-CINEMA or P.ADJ - EXPOSURE for preventing overexposure.
Normal 4:3 Ė white flowers are overexposed
PRO-CINEMA Ė much better.
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Old August 11th, 2004, 10:28 AM   #8
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Mikhail, I see a resolution difference in those first two frames. The two vertical 400-800 sets show distinct and individual lines in interlaced but in frame mode the center becomes indistinguishable.

I don't know the proper way to read a resolution chart so the above may not apply.
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Old August 11th, 2004, 10:38 AM   #9
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Hey Michael! Thanks for providing those images!

Can you tell us how you obtain the images? Did you use any special processing (ie. deinterlacing).

Tommy is right about the fact that there is a distinctive difference between the images at the vertical 400-800 area, BUT since it's vertical resolution we're talking about here, shouldn't we be looking at the horizontal lines? (Correct me if I'm wrong, I'm making an educated guess here :P)

Anywho, if you pay attention to the left horizontal 400-800 area, you'll notice Frame mode distinctively separates the lines while Interlaced shows some lines blurred together.

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Old August 11th, 2004, 12:43 PM   #10
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That's really not a good test. Interlaced grabs will look worse than frame mode because frame mode has twice the information. A better test on a static target would be to snap a photoshot to tape with the cam set for Progressive mode then shoot the same image in frame mode and pull a frame. Then, compare those two.

You read the vertical resolution on the horizontal diagonal lines. You will have to have pretty good eyes to discern difference between the two.
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Old August 11th, 2004, 12:53 PM   #11
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I mean the resolution is very similar in both modes. If we look at XM2ís snapshots, or another cam that has FRAME mode, a difference will be evident.

I think modern DV-cams have very high resolution. To prevent thin horisontal lines flicker on interlace TV, digital processor have to apply vertical blur over the image. So horizontal resolution decreases. May be progressive images donít need so much blur?

No processing used except jpeg compression. I use ScenalyzerLive for frame grabbing natural PAL-DV size (720x576). Each picture contains one frame (two fields).
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Old August 11th, 2004, 12:54 PM   #12
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Guy Bruner said: "That's really not a good test. Interlaced grabs will look worse than frame mode because frame mode has twice the information."

Isn't that the point though? Frame mode has twice the information which makes it better than Interlaced?

"A better test on a static target would be to snap a photoshot to tape with the cam set for Progressive mode then shoot the same image in frame mode and pull a frame. Then, compare those two."

Well, if we're looking at video quality, shouldn't we just compare the normal interlaced mode and progressive in video mode? I mean, even if the progressive photoshot that was recorded to tape is better than a frame pulled from the same scene recorded in frame mode, that doesn't mean much since you can't record videos in photo mode.

Sorry if I'm misunderstanding something. I also want to get a GS400 so I'm trying to get my information straight. :)

-KiN
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Old August 11th, 2004, 01:52 PM   #13
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We are talking about basic resolution measurements on a static image. Since the subject is static, there is no motion blur between the two fields. A progressive photoshot would be more representative of the frame resolution after combining the two fields from interlaced mode. Since both fields are taken at the same time in frame mode, there is no need to do that.

If you deinterlace the interlaced mode fields using software, you will degrade the resolution. If you do a frame grab and only take one field, you only have half the information and again degrade the image. All I'm saying is for a static comparision, it needs to be apples to apples.

For a motion shot, interlaced frames will look worse due to motion blur between the two fields while frame mode will look sharper because the two fields are taken at the same point in time.
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Old August 11th, 2004, 02:22 PM   #14
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"We are talking about basic resolution measurements on a static image. Since the subject is static, there is no motion blur between the two fields. A progressive photoshot would be more representative of the frame resolution after combining the two fields from interlaced mode. Since both fields are taken at the same time in frame mode, there is no need to do that."

Hmmm, since there's no motion blur between fields in a static image, wouldn't it work just as well if you compare an interlaced static video recorded to tape and a frame mode static video recorded to tape? If the shot has no motion involved, then an interlaced image would look just like a progressive one right? (since there's no difference between the fields) I don't understand what you mean by progressive photoshot. Are you talking about using the camcorder's still image mode?

"If you deinterlace the interlaced mode fields using software, you will degrade the resolution. If you do a frame grab and only take one field, you only have half the information and again degrade the image. All I'm saying is for a static comparision, it needs to be apples to apples."

There are quite a few software deinterlacers that do not degrade the resolution of an interlaced footage UNLESS there's motion. A smart deinterlacer would be able to leave the static areas alone and not interpolate and blend the fields.

"For a motion shot, interlaced frames will look worse due to motion blur between the two fields while frame mode will look sharper because the two fields are taken at the same point in time."

So are you saying that for static shots, interlaced would be the winner while frame mode would be preferred for motion shots?

Thanks for your patience, Guy!
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Old August 11th, 2004, 02:33 PM   #15
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Guy Bruner, I can't imagine moving EIA1956 chart. Can you? ;-)

>>> Interlaced grabs will look worse than frame mode because frame mode has twice the information.

It hasnít. I believe you know as "progressive" video is stored on the DV-cassette? As two fields. Both you can see on the each grabs.
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