Originally Posted by Stradigos

I've seen a way to do this with a face, but I'm sure it's not as good as the polarization way.

1) Use the shadow/highlight feature in Photoshop to normalize the values.
2) Bring the oils out... duplicate the layer, desaturate it, then open up the levels and adjust the settings so you bring out highs of the image.
3) Take that, make an alpha of it, and then use it to select the pixels on your original diffuse layer, then add a curves adjustment layer to that and bring it into range.
4) If you start to see a loss of detail from this or a loss of saturation, mess with the contrast, curves, and hue/saturation.



It does a pretty bang up job for a software solution. Results may vary, and it still requires a good clean shot. You just have to ask yourself if doing all that polarization work is worth it for the content you're creating.

PS: These images and steps were taken from "Character Texturing for Production" with Ben Neall on Gnomon Workshop. Link to product page found here: http://www.thegnomonworkshop.com/sto...for-Production

How are you supposed to get the steps 3 and 4 to work? I don't how how to get the levels right to remove the highlights. I'm using 3d.sk images so I don't have access to fancy poloarization photography. I also use the desaturated image as an curve adjustemnet layer but it not taking out all of the specularity.

Originally Posted by Ace-Angel

So in truth, we all look like the Silver Surfer?

I guess we do, when we are under what looks like hundreds of lights (Reflections in her eyes).

Cool, gives a whole new meaning to the pick-up line of "Hey, wanna ride the silver rode?"

Heya peeps,

I was wondering if anyone knew the names of filters one would use to filter out your standard Spec/Diffuse/Cavity setup in the images one takes with a camera?

I know that Polariztion Filters (Linear) is what you need to get a flat diffuse, and negate the Specular, but what would I need to do for the opposite, where I want to only 'see' and pull the Specular?

I found this 'formula' for the Specular, which nice and all, but I don't recall windows or photoshop having the ability if create and manage HLSL code:

http://filmicgames.com/archives/233

So yeah, any pretty help here peeps? Would be grand!

in photoshop Image>Calculations lets you do some simple math on layers, add/subtract etc with a few options.. that might get you some of those layers.

http://www.polycount.com/forum/showthread.php?t=95386

I don't think there are any filters that will do what a polarizer will do to get just spec or "cavity". You'll have to do something more complex.

@rube: Thanks, I actually tried that, but photoshop (CS5 atleast) seems to do that based only per channel basis, I tried setting up a Macro so that it will do math (subtract) from each channel, and then copies them all in another tab and pastes them in the channels, but I couldn't get it working.

On the other hand, a simple subtract from layers will totally make the object look inverted in color, as opposed to the site math, which gives it a more 'relaxed' hue. Mine currently look's completely 100% dialectic, which doesn't look the same in the site.

@EQ: Haha, thanks, but I kinda did already post and look up in that thread, problem is, the only 'reference' image is that of "Emily", and even then the math behind how to get Spec only is not explained.

The link I posted up has a HLSL method of 'retrieving' the Spec and the 'correct' color, but I don't know how it would be compiled or be made into an Action or PS.

Here is the text I'm referencing to:

If the first image is image A and the second is image B, the diffuse image is 2*A and the specular image is B-A. Of course, these images are stored with the sRGB profile. So here is the shader code to compare the two images and separate them out, and store the result as an sRGB image. As always, this code is not actually tested.

Oh I figured you just missed that post, why not post in that thread then as it seems to be exactly what you're interested in? I can merge the threads if you like.

Yeah, sure, should fit.

You say a linear polarization filte.r. I'm actually currently setting up a camera setup to capture specular, diffuse, scattering based on rgb, etc, and I'd really like to know should I be using a linear rather than circular filter? I had a hard time finding info based on what I'd specifically like to do and I read that the circular still allowed for auto focus so I just got that (sorry if it seems like I'm hijacking).

Originally Posted by Gestalt

You say a linear polarization filte.r. I'm actually currently setting up a camera setup to capture specular, diffuse, scattering based on rgb, etc, and I'd really like to know should I be using a linear rather than circular filter? I had a hard time finding info based on what I'd specifically like to do and I read that the circular still allowed for auto focus so I just got that (sorry if it seems like I'm hijacking).

I would like to know the difference too, in the article Zac linked too I think the linear Polarizer was referring to the film the author placed over the flash?

Not a problem mate, should be useful for other peeps too.

Some stuff which might help shed some light:




I have an instruction manual here next to me which is pretty big, but here is what is written in it:

Circular is exactly the same as Linear, only that it's mainly used with Camera's which cannot Meter exposure correctly. Meaning camera's which are 'divided', refracting, prism or half mirrors.

So basically, same stuff, only used really for certain camera's that lack an automatic/or manual controllable exposure and which fall under a certain qualifier.

Another one that seems to be popular in the manual is this:

Polarize-Conversion: Same as linear, but enabled tungsten film to be used in daylight , plus also serves to darken the sky as well increase color saturation in general.

So yeah, been scouring the manual for over several hours and still no dice on anything only captures reflections, all of them seem to negate it.

What you are looking at with 'Emily' was done by Paul Debevec (the grandad of GI, basically). There was a TED about it years ago. This tech was used in Benjamin Button, and Tron w/ DD. We duplicated this at work to a limited extent... you really need a custom light rig to make it work. We used a home built stereo rig, but I don't think that's the best approach.

If you wanted a home brew version, you need your camera with CPL, and polarized light sources. To get two images w/o your talent moving is the hard part. My thought was to get four flashes, and set them up in tandem... one w/o polarization and one with on each side. Then depending on how fast your camera syncs w/ flashes... maybe 1/250-1/400s try to pop off one shot with and without. I've seen custom flash rigs for sports photography, but I have no idea how to rig something like that up.

As far as the CPL/Linear polarizer goes... you need a CPL if you are using modern cameras (and you all will be) so your camera meters properly. You should be shooting everything on manual anyway, so everything is as consistent as possible. There is no filter that is going to give you straight cavity/specular/reflection... that's not how the world works. It's just like how polarized sunglasses work. This is all fairly new in production for film.


http://www.ted.com/talks/paul_debeve...ital_face.html