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Wet/Liquid Gate Scanning Result Question


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#1 Frank Chang

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Posted 24 August 2016 - 06:26 PM

Got a question about wet/liquid gate scanning. Attached is one frame sample that shows some white spots.

The film scanning results are perfect, except for a few seconds of videos that will contains

white spots like the sample image. Should the wet/liquid gate have took care of the

spots automatically? What are those white spots ? And are there better ways to scan in order to

minimize those white spots? Before the scanning, the film have gone thru professional cleaning/washing,

etc.

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Edited by Frank Chang, 24 August 2016 - 06:37 PM.

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#2 Shawn Sagady

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Posted 24 August 2016 - 06:55 PM

If I remember my lessons correct, white debris like that was dirt on the negative, so in theory yeah wet baths are supposed to get rid of things like that but if its something super grungy on the film might not have been caught.


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#3 Frank Chang

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Posted 24 August 2016 - 07:19 PM

Thanks


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#4 Frank Chang

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Posted 24 August 2016 - 07:38 PM

And I have saved DPX 16 bits and TIFF. Both file format are 73MB for each frame.

Does this sound correct for 4K scan?

 

Also, as a side question. Most people I know says they like to scan frame to the images.

But there are a few says overscanning, which contains the rails. Are there any benefit

to overscan?

 

To maybe answering my own question above, I did notice that scan frame to images

does leave out a little bit of images on the right side? Is this normal? Or perhaps

this is the reason some do overscan? 


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#5 Richard Tuohy

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Posted 24 August 2016 - 09:43 PM

Hold on, wet gates surely just do one thing. They fill in base side scratches on the film by using a liquid with the same refractive index as the film base. They don't clean film. A white spot is sparkle - something dark on the negative. Depending on what it is, an ultrasonic cleaner might get it off. But it might not if it is stuck on the emulsion side.
Richard
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#6 Frank Chang

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Posted 24 August 2016 - 10:01 PM

Hi Richard. It did went thru ultrasonic once and a rewash procedure. The film is about 30 years old that was inside the metal can and was

only discovered recently. Glad the condition of it is still excellent. I was just not sure why of the sparkle, especially it went thru those clean

and wash procedures. Is it normal for film scanning result showing some sparkle? This is my first scanning project, so I am still learning.

Thanks in advance.


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#7 Dirk DeJonghe

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Posted 24 August 2016 - 11:55 PM

Your best bet is to do digital dustbusting. We use PFClean very effectively but there are other means. Wetgate will not remove embedded dirt as Richard indicated.
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#8 Frank Chang

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Posted 25 August 2016 - 07:41 AM

I did the scan as flat/raw. Is PFClean ok for flat/raw type of scan?


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#9 Perry Paolantonio

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Posted 25 August 2016 - 07:51 AM

As others have mentioned, wet gate is only useful if you're dealing with base scratches *and* the scanner uses a collimated light source. Modern scanners with diffuse LED light sources perform the same function as a wet gate, because the light is bouncing all over the place and doesn't refract in base scratches in the same way a focused light source would. What kind of scanner was used, just out of curiosity?

 

Are you scanning original negatives, or an intermediate? If it's an intermediate, it's possible the dust was on the original neg, and then transferred to the intermediate. Thus, it's baked in and is part of the picture now. No amount of cleaning would take that off. If it's the original neg and an ultrasonic cleaning didn't get it, then digital is the way to go. PFClean will do it, but it's a bit of a nightmare to work with, and is pretty crash prone. If you only have a few spots here and there, you might be able to do it in Resolve, using the built-in dustbusting tools. All manual, but they do work. I wouldn't do a super dusty film that way, but it's free, and the only caveat is that you need to be working from a DPX sequence to use those tools. It won't work on Quicktime files or other containerized media. 

 

Regarding the question about Overscanning - that's more of a personal preference thing. If you're using a pin-registered (optically or mechanically) scanner, you're going to get a very stable image. If you're not, the film may bob or weave a bit in the gate. If you want to stabilize it, having the frame lines and perfs visible can help you to do that in post, by giving you a consistent reference point. One thing to bear in mind with overscanning, though, is that if you get a 2k scan that's overscanned, you should ask the lab to make sure they give you a slightly bigger scan, so that your frame area is still 2k. If not, it'll be slightly smaller. In most cases this doesn't really matter much, but if you need to have 2k or 4k, you will probably want to scan at 2.3k or 4.3k, respectively (or something around that size, depending on the amount of overscan you want). 

 

-perry


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#10 Perry Paolantonio

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Posted 25 August 2016 - 07:53 AM

I did the scan as flat/raw. Is PFClean ok for flat/raw type of scan?

We don't do restoration on the flat files - if you do, then when you color correct you might expose defects in the restoration fixes that weren't visible in the flat scan. Restoration should come last, after you've finalized all your color correction. 

 

You *can* do it, but you'll probably have to go back after grading to re-do stuff, so I don't recommend it. 


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#11 Dirk DeJonghe

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Posted 25 August 2016 - 10:12 AM

With PFClean, you take a sample of previous and next frame, just large enough to cover the defect. The program will motion interpolate if possible, in case of very rapid movement between frames, it can be set to only take local pixels from current frame. You can also make it interpolate for flicker if present; we always dustbust before colorgrading. There also is an automatic mode that works well if the shot is fairly static. We prefer the manual mode. I think you can get a 30 days trial version. It is a very deep program and will require many years of practice to master most of it. On the other hand, the dustbusting is fairly straightforward and you can see the result immediately. You can render to a different directory so you don't overwrite your original files if you are not sure of your skills.

I think photoshop also has a similar but less powerful tool, if only for a few dozen frames, it might work.


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#12 Frank Chang

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Posted 25 August 2016 - 10:13 AM

Hello Perry. Thank you for the detailed info. Much appreciated as this is my first project in actual film to digital format. 
 
It was scanned with spirit 4k. It is an orange film without audio track. The scanned film is FF 35MM Color I/N "B" Wind 1 Roll. That's what the scanning lab indicated. I am
not sure what "FF", "B" , "Wind" means.
 
The scanner used is spirit 4k with wet-gate. I didn't choose to do overscan. I had the lab scan to "Framed To Image" for 4K scan. I did notice that I lost just a little bit of the right side
of the image. Is this normal? Or could the lab do more to the scanning area for the 4K or 4.3K without capture the rails?
 
The good thing is most of the footage are clean with only a few here and there.
 
I do understand that the wet-gate deal with scratches. I am just wondering why the leader with the count down 8,7,6, etc still shows scratches? I don't need that
part of the footage, but I was just wondering how come the wet-gate didn't do anything to that?
 
I had the lab saved DPX in 16 bits and TIFF files (both formats are 73MB per frame), Am I better off using DPX or TIFF? I assume the file quality are the same
because they are both 73MB each.

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#13 Perry Paolantonio

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Posted 25 August 2016 - 10:48 AM

The scanned film is FF 35MM Color I/N "B" Wind 1 Roll. That's what the scanning lab indicated. I am

not sure what "FF", "B" , "Wind" means.

 

FF = Full Frame (as in, not matted to a widescreen projection aspect ratio; very common)

 

I/N probably means Internegative. 

 

A and B Wind refers to the orientation of the emulsion 

 

 

 
I do understand that the wet-gate deal with scratches. I am just wondering why the leader with the count down 8,7,6, etc still shows scratches? I don't need that
part of the footage, but I was just wondering how come the wet-gate didn't do anything to that?
 

 

 
Leader shouldn't be what you're looking at. It's often re-used and reprinted by the lab and is rarely as clean as the film itself. Dust and scratches are baked into subsequent printings of standard leaders, kind of like multi-generation photocopies. no cleaning or wet gate will deal with that, because they're printed-in scratches, not actual scratches in the film.
 
That said, wet gate is not a panacea. It's good for some things in specific situations, as described above. But it won't deal with very deep scratches. it primarily does its thing on light scratches, and only on the base side of the film.

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#14 Frank Chang

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Posted 25 August 2016 - 11:01 AM

Ah, thanks Perry, I was wondering about that (the leader). Thanks. Haha, now I know wet gate is not a panacea. :) Good thing is the QT raw footage

is 95% perfect (i.e. without scratches, etc) just a few sparkle here and there for a few seconds. Should be easy to deal with after color correction.

 

The scanner used is spirit 4k with wet-gate. I didn't choose to do overscan. I had the lab scan to "Framed To Image" for 4K scan. I did notice that I lost 
just a little bit of the right side of the image. Is this normal? Or could the lab do more to the scanning area for the 4K or 4.3K without capture the rails?
 
 
PS: Is I/P (InterPositive) one level better generation than I/N (InterNegative)? Or the otherway around?
I tried to get the I/P reel but it was in a very bad shape and I/N for some reason, was fine
even it stayed unopened in the metal can for 30 years. I/P was just stored in a cardboard box.
Original camera negative is nowhere to be found.

Edited by Frank Chang, 25 August 2016 - 11:07 AM.

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#15 Perry Paolantonio

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Posted 25 August 2016 - 11:08 AM

The scanner used is spirit 4k with wet-gate. I didn't choose to do overscan. I had the lab scan to "Framed To Image" for 4K scan. I did notice that I lost 

just a little bit of the right side of the image. Is this normal? Or could the lab do more to the scanning area for the 4K or 4.3K without capture the rails?

 

I don't know how wide the Spirit can go, maybe Rob Houllahan does (he's got one)? 

With many modern scanners, the camera/film positioning can be varied. Older units had fixed camera positions, like our Northlight. So the framing is what it is (you can only widen it by physically widening the gate, which means machining it to be larger, and even then, there are limits. On a scanner like our Lasergraphics, the scanner is always scanning the film pretty much from edge to edge, and then cropping/scaling downwards. So you can do a very large overscan, or a small one, depending on what the job requires. 

 

-perry


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#16 Frank Chang

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Posted 25 August 2016 - 11:12 AM

Thanks, Perry.


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