Black polyester raincoat looking purple

[Kaku Ito]

I'm on post-production of a feature film and finding some shots under the sun, black polyester rain coat looking purple instead of being black. The same raincoat in the shade or in the night scene looks fine, black.

The crew did used ND filter with infrared coating.

What would be the best way to compensate the color in this situation?

 

[Pawel Achtel]

I'm on post-production of a feature film and finding some shots under the sun, black polyester rain coat looking purple instead of being black. The same raincoat in the shade or in the night scene looks fine, black.

The crew did used ND filter with infrared coating.

What would be the best way to compensate the color in this situation?

Not all ND filters "with infrared coating" are made equal. Which filter did you use? I suggest using hot mirror, such as Pancro which, unlike dichroic coatings, reflects both visible and IR spectrum equally.

 

[jimhare]

I thought an IR filter had to be a mirror by definition, meaning a coating wouldn't adequately do the job.

 

[Pawel Achtel]

I thought an IR filter had to be a mirror by definition, meaning a coating wouldn't adequately do the job.

Dichroic coating is a mirror, but it is selective. It reflects selected frequencies only. In this case, IR or portion thereof. This can be a problem depending on the cutoff frequency and angle. They are not 100% effective. Filters like Pancro are full spectrum mirrors, reflecting visible light and IR spectrum equally. So, visible light to IR ratio remains unchanged regardless of density.

 

[Kaku Ito]

Thank you very much for thorough information. Pancro looks really great.

We recommended to use Tiffen IRND, but I don't know at this point what they have used.

Is there any effective solution to correct in the post?

 

[Adrian Sims]

With an advanced color correction plug-in like Color Finesse you can 'eyedrop' four sample areas of the purple raincoat and adjust you color wheel to turn the purple back to black. Keep a close eye on any other elements in the scene that are close to purple in the color spectrum, as they will shift to black as well (purple flowers etc.). If done right the change shouldn't affect skintones too much, but best to check with a reference split/swipe across the screen.

 

[Kaku Ito]

Adrian,

Thanks, it's going to be professionally color graded with da vinci but the clients weren't planning to extensively color grading, so I was wondering if there's any specific way to fix it. There's a cast that has purple cap, so they probably have to give up on that. The raincoat guy is more important. So, as you say, they have to give up on other things and fix the rain coat.

 

[Paul Leeming]

Our Formatt IRND filters have never given us any trouble either Kaku.... :thumbsup:

 

[Kaku Ito]

Our Formatt IRND filters have never given us any trouble either Kaku.... :thumbsup:

Well, they learnt in hard way.

 

[Alexis Hanawalt]

Adrian,

Thanks, it's going to be professionally color graded with da vinci but the clients weren't planning to extensively color grading, so I was wondering if there's any specific way to fix it. There's a cast that has purple cap, so they probably have to give up on that. The raincoat guy is more important. So, as you say, they have to give up on other things and fix the rain coat.

It should be an easy fix - it's just secondary color correction - like making a blue sky bluer.

Black polyester seems to give off tremendous amounts of IR. We had this purple issue come up on a shoot indoors with tungsten light.

 

[Birns and Sawyer]

Another note is that Tiffen makes two kinds of IRND filters, the standard IRND filter, and the Hot Mirror IRND. The IRND are designed for Sony cameras, such as the EX series and the F900, F23/35. The Hot Mirror IRND provide more IR protection, and that's the kind you need for the RED.

So, your clients may have used an IRND filter, but not a Hot Mirror IRND, which would not block enough/the correct IR pollution.

 

[Brandon Kraemer]

Like Adrian and Alexis said, it's a simple secondary color correction, you will need to apply a hold out matte to keep the other purple elements in the shot from being corrected as well. Any software based CC package can do this, most have built in trackers too if necessary.

 

[Kaku Ito]

Thanks Alexis, Paul, Adrian and Pawel.

It's too bad if they listened to us them this wouldn't have happened.

 

[Kaku Ito]

Brandon,

That's what I'll do but even with the colorist presence yesterday, the clients were concerned. They are going to use da vinci, so I'd imagined it could handle such job.

 

[Brandon Kraemer]

Brandon,

That's what I'll do but even with the colorist presence yesterday, the clients were concerned. They are going to use da vinci, so I'd imagined it could handle such job.

Kaku,

I don't know how many shots of what duration you have with this raincoat in them, but it might be the case where you will need to export these shots and do secondary CC in a software package, either before or after your da vinci session to specifically target this issue. There are lots of options for doing this with most any Non linear edit system. The for mentioned synthetic aperture, which makes plug-in's for AfterEffects and Final Cut Pro, Avid DS has this kind of tool, of course Apple's Color or Shake can do this work, Smoke/Flame systems too, etc.

If the Da Vinci has "power windows" you can use them as a selective tool for creating a hold out matte and apply secondary CC to just the raincoat. Have faith in the colorist and/or composite artists to get this done, however... it might take more than one pass on a single system to achieve the desired results.

All the best,

Brandon.

 

[Kaku Ito]

Thank you very much for the detailed information Brandon.

I do have Color Finesse, so I'll looking into it (I'm not much of colorist though, but I can experiment).

 

[Brent J. Craig]

They are going to use da vinci, so I'd imagined it could handle such job.

The skills of the colorist are much more important than the gear. A great colorist can do things on a laptop that a junior guy couldn't accomplish in a 5 million dollar suite.

For a TV series, the post facility might be giving you their junior colorist and saving the hotshots for commercial clients.

 

[Kaku Ito]

Using secondary on Color and select purple channel and shift the purple to green side on the highlight did enough correction to me. There was another cast that was wearing a purple cap but I was able to mask that out.

Thanks Brend and Thomas for more information.