Optical Filtration vs. Digital Filtration

[Timur Civan]

For what my experience is worth, this is not the case, neither Benckert or others with strong experience in post or cinematography seems to agree...

How do you replicate the effects of a polarizer in post?

 

[Dave Blackham]

Ive done a fair bit of post in the past and whilst I would never want to compromise on quality but sometimes working efficiently on a show is a compromise worth doing if it gets you to you goal more efficiently. If for instance you can replicate an in camera filter in post but its a really time consuming ask to do it then it may be worth doing in camera knowing what the result will be and will get the show to air or on screen then I don't see the issue. The main thing is you deliver whats needed efficiently and its controllable. I don't see anything wrong a tall with in camera filtration in that respect. However, Ideally Id prefer to leave options open in post in an ideal world.

I still think we need a resource and/or new tools, probably for post that can replicate in camera filtration as accurately as possible. Id suggest a resource that can provide suitable techniques or presets to say replicate highlight roll off or halation. Id also suggest if any one has the expertise to create a high end product to that offers Post Filters to replicate in so far as possible in camera filtration then Id buy them for a start.

Patrick mention options and with Epic and I still feel we have many more options than any other camera offering right now.

 

[Mike P.]

Does anyone have any .r3ds with: BPM 1/8, HBM 1/8, LowCon 1/8, and clean?

I have different .r3ds with some of the filters, but none that are a set done by the same person (at the same time with the same lighting.)

 

[Jon MIchael Puntervold]

How do you replicate the effects of a polarizer in post?

I don't.

 

[Marc Wielage]

Id also suggest if any one has the expertise to create a high end product to that offers Post Filters to replicate in so far as possible in camera filtration then Id buy them for a start.

It depends on the filter. I know of a case with a filmmaker who's a big fan of coral and straw filters, and insisted on using them in camera on a digital shoot. The problem was, due to lack of scopes, he wound up clipping the red channel on many, many shots. We were able to tweak the levels to a point in post and get a little of the detail back, but most of it was pretty much sheared off, and there wasn't time to recreate the lost detail from the green and blue channels. The filmmaker insisted that he wanted to see the look right there on the set, and (at the time) on-set color correction was a rarity.

What was interesting was that we also had quite a few blue-screen shots on this project, and on those he couldn't use the filters (because of adverse effects on the composite), which forced me to recreate the same look digitally. We got pretty close, but for lack of a better word, it's not as "organic" as an in-camera filter. But very close. Nobody noticed in the final, and the movie went on to make $100M.

The advantage of doing it in post is that the look is 100% controllable and you can change your mind later. The disadvantage is that somebody down the line may override your judgement and take all the filtration out, altering the look of the scene. I know of many DPs who want to deliberate bake in the look during production for this reason.

Glimmerglass and stuff like that is a look that's hard to get any other way, but I can get pretty close to a 1/4 or 1/2 black pro mist with some selective highlight blur/defocus. In some cases, it takes time, but if it's just an overall, this is a quick process.

My own preference would be for DPs to shoot tests and avoid going too far with the filtration, particularly if the results start "bending" or pushing the image over the edge. And it's true that a lot of matte box filters react differently with (say) a 20mm lens than they would a 200mm lens, just because of the image area. In the 1980s, I can recall this being an issue on a sitcom where (for certain reasons) they chose to use a Mitchell B fog filter on the star's close up camera. Nowadays, we'd have much more control over this look and wouldn't go nearly as over-the-top.

 

[Mike Nagel]

Hi guys,


ran some filtration tests a few days ago with optical net diffusion and / or a Schneider Low Con 1/4.

Exported 16 bit tiffs from RCX and started playing in PS. The Low Con 1/4 can somewhat be replicated by the Tiffen FX suite. The highlight diffusion is identical (in stills, I did not test moving images) but the shadow and black level diffusion is not, as it can't be as the clean take did not record (raised black level / shadow) data that the take with the LC 1/4 recorded.

But, that can actually look quite interesting in post if you're just looking to diffuse the highlights but leave lower brightness values as is.

Optical net diffusion is almost impossible to re-create, at least in my quick tests, maybe I did not choose the correct tools / workflow. I used Gaussian Blur, and if you have just some light optical net diffusion you can somewhat get there with some mild GB. Obviously u can never re-create a specific net type with GB.

GB used a little bit is okay, but you can't re-create heavy optical net diffusion with GB. GB (more or less) smears the pixels, degrading IQ and resolution. If you're trying to re-create heavy net diffusion by using a lot of GB you're destroying your image and you'll never get the look the real live optical net diffusion created.

Maybe there are specific digital net diffusion solutions or workflows for post ? What are your workflows for these cases ?


Ran more quick tests today - exterior shots - with the LC 1/4 and a HBM 1/8:

1) clean
2) w/ LC 1/4
3) w/ LC 1/4 & HBM 1/8

Here are file links for all of you who wanna play around and see what they can do in post, or maybe demonstrate how much they can match optical filtration in post ;-)


1) clean - R3D trim

https://www.dropbox.com/s/mcnnmq5fu...ior sky with trees - clean - 35mm - 1-384.R3D

2) w/ LC 1/4 - R3D trim

https://www.dropbox.com/s/ib3a97c33...h trees - with Low Con 1-4 - 35mm - 1-384.R3D


3) w/ LC 1/4 & HBM 1/8 - R3D trim

https://www.dropbox.com/s/dl2yu0u20...h Low Con 1-4 with HBM 1-8 - 35mm - 1-384.R3D

4) PS file with all 3 files above, each in a separate group - all 16-bit tiffs exported from RCX - I created a duplicate of the clean take and applied the Tiffen FX Low Con #2 (from the Tiffen FX suite) for all of you who do not have the Tiffen FX suite, so you can play with it and see how much it matches the real live optical LC 1/4 image that is one layer above it. I think (--> hope !) #2 matches the 1/4 by definition (?).

All tiff exports from RCX were RC3/RLF, so u need to set your Cineon curve etc in PS for each image...

https://www.dropbox.com/s/ay3tjti50...on 1-4 Test & HBM Test - Exterior - start.rar


Let us know your findings !

- M

 

[Robert Ruffo New]

As I mentioned in the other thread, the trouble with post diffusion to create halation is that most post houses opt for the method of blurring a luminance key of the highlights and then layering this back over the clean shot. The problem with this layering technique is that you increase the contrast of the highlights and if you lower them back down again (as you have control over this) you also lower the halation effect. And there is some loss of sharpness in the highlights. It's a pretty look, and flattering for skin tones, but I feel that if you just want a bit of glow around highlights with minimal loss of sharpness and no change in the gamma of the highlights, a light camera filter is better, though keep in mind that designs like Classic Softs and Hollywood Black Magics have a pattern designed to soften detail as opposed to just mist particles like a ProMist or Frost filter might have. Black Magics are a combination of HD Classic Softs and an 1/8 Black Frost, and both increase halation but the Classic Soft portion is designed to soften detail more. Of course, mist filters also soften the image a bit too, just not as much as other types of diffusion.

As for using low-cons, ultra-cons, etc. for increased dynamic range, the theory is that the filter before it hits the sensor (and before recording, compression, etc.) would lift the blacks and some low-level detail along with it up the chain a bit, higher above the noise floor. However, as with techniques like flashing in film, I've found that there is only a 1/3-stop increase in usable detail, most of the perceived increase in shadow detail is just lifted blacks, and once you reset them to black in post, a lot of the lower-contrast look disappears. In other words, I don't think filtering is going to really increase DR by that much, and certainly not if you do it in post since you are limited to whatever DR was recorded.

As for the notion that shooting without filters (other than ND's) and just working with the raw files somehow gives you the most flexibility, this is not completely accurate. If, for example, you wanted a super deep blue tone to the image, a blue filtered shot would color-correct easier and with less noise than a neutral shot because you aren't pushing the blue channel as heavily to achieve that look. So all not filtering does, in terms of flexibility, is give you the flexibility of not making up your mind as to what you want, but it does not necessarily mean that you will always get the best end result.

Now perhaps there are post software diffusion tools that do not impact the sharpness and gamma of the highlights, maybe the Tiffen DFX filters(?), I just haven't seen any at the post houses I've used.

David I have looked at hundreds of options from dozens of vendors including post-house home brew software and I have yet to find a halation/diffusion solution that did not have the problems you describe. Post solutions also tend to look overly uniform and somehow "inorganic" to me, I'm guessing you know what I mean.

 

[Mike Nagel]

here's a nice optical filtration test:

http://www.cinema5d.com/news/?p=20634

6 cameras w/ start time in video:

00:30 Arri Alexa
08:00 Red Mx
18:30 Canon 7D
27:40 Sony F65
36:10 Sony FS700
44:00 Canon C300

Filter's tested:

- Glimmerglass 1/8 (only on Alexa)
- Glimmerglass 1/4
- Glimmerglass 1/2
- Glimmerglass TM 1

- Blk Glimmer Diff FX 1/4
- Blk Glimmer Diff FX 1/2
- Blk Glimmer Diff FX 1

- Digital Diff FX 1/4
- Digital Diff FX 1/2
- Digital Diff FX 1
- Digital Diff FX 2

- Soft FX 1/2 Blk Promist 1/8
- Soft FX 1/2 Blk Promist 1/4
- Soft FX 1/2 Blk Promist 1/2

- Blk Diff FX 1/2
- Blk Diff FX 1
- Blk Diff FX 2
- Blk Diff FX 3

- Softnet Black 2


Statement from test:

"There is a big misconseption about adding filter effects in post! Digital filters (Post Production / Grading) can NOT reproduce what a glass filter does. We have tested Tiffen’s very own Filter Suite and also asked the colorist to reproduce an effect on Filmlight Baselight which could not be done as the nuances are too fine and software does not know what goes on around the recorded frame, while the glass filter on camera reacts to all the light sources around, which is especially necessary on moving shots."

 

[Ketch Rossi]

This is an other interesting article on RED.com showcasing the use of Low Con filter addd in post, which is what I am talking about by not using filter on capture as I did not on this frame.

Major difference is that when added in post one can also choose the area to be covered or effected by the filter in post, as in this particular case, it can be made to cover the entire area, or for Fashion Photography most usually I would want to mask out the eye so to maintain it crisp and sharp, yet there is a choice, with filters applied in camera, either behind the lens, On sensor or on front of the lens there is no other choice then the one made upon capture.

 

[David Mullen ASC]

Fine for a fashion shoot, but imagine doing it for a thousand cuts of a feature, or even worse, if you wanted it for dailies on a feature, doing it to maybe 100 hours of material by the time you are done. You could save it for the end of post, but what if the actress wanted to look at dailies or an HD monitor on set... and was horrified to see how sharp the image was? Telling her that you'll fix it in post down the road in a few months may not fly with her, or maybe as a DP you'll be asked not to come back to work the next day.

Besides, diffusion is not only used for cosmetic reasons on a close-up, they may be used on everything as a basic look, and then we're back into the reasons I gave before, that digital diffusion tends to lose sharpness in the highlights more than a light optical diffusion can do. Losing sharpness in the highlights may be great for a close-up but doesn't work as well for a wide shot when you still want the halation of diffusion but you don't want a blurred look to the highlights like the example above has.

 

[Mike Nagel]

the "keeping the eyes" clean is one thing that would really be interesting to have full control over... but with digital filtration on MOVING images you'd have to create a mask and then animate / track the mask depending on how much the talent moves in the shot... lots of work (as in: PITA), but I'll have to test that and compare results...

and if digital filtration cannot truly re-create optical filtration for MOVING images, and u know you want filtration for that shot, optical filtration might be the better way to go... I love control but in the end only superior results count ! ;-))))

since a lot of time the final image is sharpened, you could then still use a mask over eyes on optical filtrated footage and make them pop more with extra sharpening (and again you would have to animate / track the mask)...

IIRC, there were optical filters that had a "blank" part in the middle that you could use to target certain parts of the frame that you wanted unfiltered... I'm sure David knows all about them...

 

[PatrickFaith]

Fine for a fashion shoot, but imagine doing it for a thousand cuts of a feature, or even worse, if you wanted it for dailies on a feature, doing it to maybe 100 hours of material by the time you are done. You could save it for the end of post, but what if the actress wanted to look at dailies or an HD monitor on set... and was horrified to see how sharp the image was? Telling her that you'll fix it in post down the road in a few months may not fly with her, or maybe as a DP you'll be asked not to come back to work the next day.

I'm slowly understanding what David is saying, in the past I have only done shorts and commercials, but on my feature I'm finding it's best to do everything I can in camera. This is kind of opposite of my past mindset. From a money/time perspective it takes about 10 seconds total for me to put a filter on, but to do that in post takes (when you add it up) about 10 seconds per frame and about $10k of software(i.e. around 1 month of computer time per hour of the film). So from a time/cost viewpoint I've changed from a post mindset to a in camera mindset just from a simple "am i ever going to get this done and on budget". Also my epic monochrome is the best thing i have, just makes sense for me to maximize it's use. Only time diffusion/contrast filters should not be used is when I have a lot of fx compositing - is just about impossible to mix in camera diffusion with fx diffusion in a seamless manner. Also with fx compositing, doing the diffusion in post "merges" the vfx/sfx with the principle photography in a clean way. But ... my primary method for composing my dynamic range/contrast is lens depth of field and lighting - i find if i mess that up all is lost anyway.

 

[David Mullen ASC]

I saved diffusion for post on two features, "Manure" and "Big Sur" -- in the case of the first, it was because I wanted that digital gaussian blur overlay glow look (though I also used some really mild filters on close-ups in-camera). On "Big Sur" it was because I wanted to glow the blacks but not the whites, which can only be done digitally.

Now with "Manure" the producer took the movie away from me and the director and color-corrected it with no digital diffusion, making me wish I had just done it all in-camera. In the case of "Big Sur", the only problem was that I was not available for the final color-correction, so the digital diffusion effect was done, but I would have adjusted the levels of it a bit differently on some scenes if I had been there. But overall, the look I intended is there, and as I said, that black halation effect can only be done in post anyway.

But in the case of two-years of "Smash", some hundreds of hours of programming and thousand hours of footage, with a tight schedule for final color-correction, basic diffusion had to be done in-camera just to be practical. Plus it makes shooting a lot more fun and you see the effect on the monitor. In fact, in the case of this fantasy number, shot with a net on the lens, the operators could control the flare by how the tilted into the lights, so it was an interactive thing, the operating was taking the diffusion filter into account. See:
http://vimeo.com/66877298
So if the scene had been shot clean, they wouldn't have timed movement of the shots to account for moments of flare.

Now occasionally we had some shots that needed additional cosmetic touch-up work, digital diffusion on a more sophisticated level than I could achieve with a filter, so I took the shot as far as I could go on set, knowing it could be improved in post if necessary. But that was only a few shots in every episode, and even then, sometimes production would whine a little about the costs of the additional time spent in post, the budget was that tight.

In fact, I had one fantasy number with a few effects where I planned on post diffusion and once we applied it, the producers wanted it left clean because that's what they had gotten used to seeing in the editing room, which is the problem with no having the look built-in to the footage, it will spend a lot of time in an editing room (months for a feature) and a lot of people start to get used to the way it looks and don't want to change it.

 

[Ketch Rossi]

Completely understand David,

what is important for every one reading me, is that what I am giving is my opinion on workflow based purely on my taste and my needs, if there is one that has similar needs to mine then they will share my tough.

To me is always more important to have the Original clean image in my RAW files, to do as I chose, then to be worried what the amount of work I need to do in Post, as I will always, with every single project, mix Fashion, Beauty, Prints, and Film.

To that, more to come as soon as I will be done with my first Short, which will showcase all my work to come, including al Feature Films, were I will always be Pulling Frames for my Gallery work.


I know I chose the harder road, but will be the one that will give me the most flexibility on image manipulation later on, and the one I know is best for me.

Fortunately there are also new Programs coming around that will allow a better Post work with some very hard filters, but IMO, while is great to have choices, we always go back to insure that what it is used, is what is in one's best interest for the individual work, and most importantly one must always know the tools, and also know the end result and limitations in the decision making during Recording.

Which unfortunately not many do take in account.

But I do agree with you, just that it is because I know exactly what I want out of my files, that I chose to always make use of NO Filtration on Camera, other then the Polarizer and ND's.


OH, almost forgot to answer also an other very important point you make about Accretes frecking out about how they look so sharp on HD monitor on set.

My med, is to always show them during the Casting what they do look like before and after, in a quick demo, which I usually do on my Laptop, and problem resolved.

Because you are right, I have seen it in person more then once, on several sets, were they just literally scream, because of how they look, with HD showcasing every single dimple, or Facial hair, imagine if they would see it on a 4K monitor, (soon they will) on set??


That is why I practice the during Cast show what is possible to do despite how they look, and avoid arguments on set when time truly costs a lot o f money, this is a habit I picked up ever since I moved to Digital form Film inStill Photography, and some of the Models would seat next to me looking on how I would transfer the files, and become horrified of the detail on their faces, while loving their eyes.

And they usually go, WOW, I love how you can do that!! And every one is happy...

 

[sam karr]

To me is always more important to have the Original clean image in my RAW files, to do as I chose, then to be worried what the amount of work I need to do in Post, as I will always, with every single project, mix Fashion, Beauty, Prints, and Film.

Interesting mix. I'm curious about your work and method. Where can I see it? Any link?

 

[Ketch Rossi]

Interesting mix. I'm curious about your work and method. Where can I see it? Any link?

You will soon Sam...

Just need to work on a new site upon my return to LA, and all will be put up, including the vid of "Carly" and all her Frame pulled from the shoot, and will be the same form now on...