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Poser - OFFICIAL F.A.Q (Last Updated: 2024 Nov 13 11:02 am)



Subject: Gamma correction and the "horde werewolf model"


piccolo_909 ( ) posted Sun, 30 September 2012 at 5:05 PM · edited Thu, 15 August 2024 at 4:04 AM

file_487105.jpg

I've been trying to decide whether or not i should use gamma correction in my renders. On one hand, it can make a picture look nice and realistic. But sometimes, it makes a render look dull/grayish and washed out, and kills highlights.

This is a particular problem with the "horde werewolf model" that i've seen used pretty much everywhere. When i render it with gamma correction ticked on, with proper postwork it comes out looking nicely on my monitor. However, when i turn up the brightness settings, the werewolf model gets "washed out", and this only happens when i render with GC on. While it may look great on my system, other people who have brighter monitors may see this "Washed out" look, and it could become a problem.

Is there a particular reason for this happening? I'm torn between using gamma correction or not. I've attached two pictures so you guys can check out. Do they look good, or are they "washed out" and bright? This first picture is supposed to be a dark werewolf, with only the blue/golden highlights showing. These second picture in the next post is white highlights and slightly brighter. Both are rendered with gamma correction 2.20.

 

 


piccolo_909 ( ) posted Sun, 30 September 2012 at 5:07 PM

file_487106.jpg

Here's the second image.

The first image with the blue/gold highlights is done with postwork, with increased contrast and the "bloom effect"

This image here with the white highlights has no postwork.

 


bagginsbill ( ) posted Sun, 30 September 2012 at 5:18 PM · edited Sun, 30 September 2012 at 5:19 PM

Don't say gamma correction - say linear workflow. Soon as you do, you'll realize you have much to learn.

You can't get linear workflow by just turning on GC. You have to have shaders and lights that are SANE, based on real physics, not constant visual tweaking and adjusting.

The goal of GC is to support linear workflow. If you want to just turn on GC and do nothing else, don't.

There's an enormous body of work in the past, all of which don't work with each other, or don't work except in specific lighting situations. Linear workflow solves all that. If you want to keep using bought things from the approaches of the past (Poser past, not professional CG in general) then you can't turn on GC.


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bagginsbill ( ) posted Sun, 30 September 2012 at 5:20 PM · edited Sun, 30 September 2012 at 5:21 PM

http://greyscalegorilla.com/blog/2010/11/what-is-linear-workflow-and-how-can-it-help-your-renders-look-better/

Quote - Computer graphics is relatively new and everything you know till now is a hack to make things work with antiquated technology.


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piccolo_909 ( ) posted Sun, 30 September 2012 at 5:40 PM

So generally if an older model is not looking right with GC, i should just turn it off?

Also, do those 2 images look washed out or too bright? Or do they look fine on your monitor?


hborre ( ) posted Sun, 30 September 2012 at 5:58 PM

I can tell you that the second image may possibly suffering from a texture ambient glow which complicate matters.  Or there may be IBL use washing out the shadows, but not enough lighting information is being provided.  As BB posted, linear workflow involves more than just adjusting lights, it involves MAT room shader modifications and tweaking to get all components working together to create the right realistic balance.


piccolo_909 ( ) posted Sun, 30 September 2012 at 6:08 PM

Yeah, in the second image a diffuse IBL is being used. I also notice the horde model ambient color is set to a grayish color, but the ambient strength is 0, so would that even matter? That ambient glow also was present in the first picture, but after applying postwork and increasing contrast, it got rid of most of it. That glow though is not present when gamma correction ticked off. So i'm not exactly sure what's causing it when GC is ticked on. This so far has only happened on this particular model too.

 


vilters ( ) posted Sun, 30 September 2012 at 6:09 PM

Usually older light sets or older shaders are to blaim.

When rendering with GC, you HAVE to adapt the lights AND the shaders.

2 NO-NO-s are;

  • The light blue in diffuse_color in some older skin.
  • Using older light sets that are not adapted to GC.

Poser 1, 2, 3, 4, 5, 7, P8 and PPro2010, P9 and PP2012, P10 and PP2014 Game Dev
"Do not drive faster then your angel can fly"!


bagginsbill ( ) posted Sun, 30 September 2012 at 6:11 PM

If Ambient_Value is 0, the color can be anything - there will be no glow from that. Mathematically, Ambient_Color * 0 = 0 in all cases except where Ambient_Color is undefined. (Like if that was any number divided by 0, or square root of -1. When colors become undefined, then really strange things happen. But I digress)

 


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piccolo_909 ( ) posted Sun, 30 September 2012 at 6:15 PM · edited Sun, 30 September 2012 at 6:20 PM

file_487110.jpg

vilter: Hmm, it might be something in the shader then. The lights are the default poser pro 2012 lights which im guessing are designed for GC, since gamma correction is on by default. Possibly someone with this model with material room experience can examine this?


bagginsbill ( ) posted Sun, 30 September 2012 at 6:16 PM · edited Sun, 30 September 2012 at 6:16 PM

In general, anything that looks like mid gray in the shader or the lights will take on new meaning when GC is enabled.  If that is being used to multiply something the impact can be huge.

Any small amount of injected luminance will be magnified. And it's not enough to look in Ambient_Color. It can be anywhere.

For example, the old V4 shaders used to have some very small amount of red injected when the light levels were low - faking subsurface scattering in shadows. That small amount of red becomes a really large amount of red when GC is enabled.

But those same shaders used some light cyan in specular to offset the added red. This was a suppression of red. The two effects were clever and carefully balanced in a way that only worked if you were doing non-linear rendering and only if the light levels were roughly the same as everybody is always using in portraits.

When GC is on, or when rendering with no lights (IDL only) or lots of other situations, those skin shaders turned all kinds of ugly colors.

Guess what - the correct shader under linear workflow is TWO NODES. That's right. It's SIMPLE.

Linear workflow is about removing hacks. It's about not having to guess. It's about not having complications.

 


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hborre ( ) posted Sun, 30 September 2012 at 6:17 PM

A zero ambient value means no ambience at all.  However, IBL intensity alone set too high will washout shadow details.  Decrease it's intensity to a considerably low value as a remedy when using linear workflow.  Otherwise, the effect appears as you posted.   


bagginsbill ( ) posted Sun, 30 September 2012 at 6:21 PM · edited Sun, 30 September 2012 at 6:22 PM

My favorite analogy:

You have been wearing glasses for years.

Somebody gives you contact lenses.

But you still put on your glasses. You decide the contact lenses don't work right at all.

The problem is - you weren't supposed to use the contact lenses and the glasses. One replaces the other.

Same thing with shaders - remove all the crap when you turn on GC. If you don't, you're doing two sets of corrections resulting in incorrect outcomes.

The most common issue without GC is dark-ish things appear too dark. So people lighten them in various ways. They add more ambient lighting - they make lighter shades of gray than they really want - other tricks. This is a compensation for gamma. Not a correction, a compensation. It works - in some situations.

Then you apply gamma correction ON TOP OF THAT. The compensation is now an overcompensation, and everything looks washed out. Duh.


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bagginsbill ( ) posted Sun, 30 September 2012 at 6:24 PM · edited Sun, 30 September 2012 at 6:25 PM

Content Advisory! This message contains profanity

Quote - vilter: Hmm, it might be something in the shader then. The lights are the default poser pro 2012 lights which im guessing are designed for GC, since gamma correction is on by default. Possibly someone with this model with material room experience can examine this?

Can't see shit, so no.

The nodes are all collapsed. We can't see what plugs into what nor any of the parameter values and colors. So nothing can be analyzed.

 

 


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bagginsbill ( ) posted Sun, 30 September 2012 at 6:26 PM

Oh wait - I see translucence!!!

Turn that off. It's just like ambient.


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bagginsbill ( ) posted Sun, 30 September 2012 at 6:30 PM

Hey do you have SnarlyGribbly's SceneFixer script?

If not you need to get it.

There are several thousand threads like this one in which I see what is wrong and suggest how to fix it.

That script captures a lot of them and performs the changes AUTOMATICALLY.


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bagginsbill ( ) posted Sun, 30 September 2012 at 6:31 PM · edited Sun, 30 September 2012 at 6:33 PM


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piccolo_909 ( ) posted Sun, 30 September 2012 at 6:36 PM

file_487112.jpg

This was after turning the diffuse IBL down, so i'm guessing that's not the issue.


piccolo_909 ( ) posted Sun, 30 September 2012 at 6:40 PM

file_487113.jpg

Here's the material room with the nodes spread out a bit.


piccolo_909 ( ) posted Sun, 30 September 2012 at 6:43 PM

Hmm, naw, i dont got the scenefixer script. I'll download it though and check it out.

I'll try another render by turning off translucence as you suggested and see if it fixes it.


piccolo_909 ( ) posted Sun, 30 September 2012 at 7:00 PM · edited Sun, 30 September 2012 at 7:05 PM

file_487115.jpg

Ok i turned off the translucence. Does it still look ambient/washed out?

Another thing i noticed is that on the image maps, it says "use gamma from render settings" Would changing these to "use gamma 1" eliminate gamma correction for the werewolf while leaving it on for everything else in the scene?


piccolo_909 ( ) posted Sun, 30 September 2012 at 7:23 PM · edited Sun, 30 September 2012 at 7:35 PM

Actually that seemed to fix the washed out look, but what happened to the lips T.T

Edit nvm, i forgot the turn off the translucence on those. Doing so fixed it.

I think that was the key to getting rid of the washed out look! Thanks bagginsbill! I turned up the brightness to make sure, and the washed out look seemed to have disappeared. I guess i gotta do this when i have GC enabled.

Does the above picture look ok now, other than adjusting the lighting?


hborre ( ) posted Sun, 30 September 2012 at 9:06 PM

It is beginning to look better.  Reflection_lite_mult should be unchecked and try reducing the diffuse_value to 85% (0.85).  The only maps that should have a gamma = 1 are displacement, specular, bump maps and transparency maps.


piccolo_909 ( ) posted Sun, 30 September 2012 at 10:19 PM

file_487131.jpg

Ok, i unchecked reflection_lite_mult, and reduced the diffuse value to .85. I also upped the specularity a bit to 1.50 to make him a bit shiny. I also used the changegamma script that comes built in PP2012 and set the gamma's to 1 for the above mentioned maps. The only thing that was missing in that script was specular. It came out a bit dark so i brightened it a few notches with my image viewer. How does it look now?

Remember that this is with basic lighting, no postwork, and not at the highest settings. I'm just trying to get him to look good material wise first and making sure he doesn't look washed out.


moriador ( ) posted Sun, 30 September 2012 at 10:37 PM · edited Sun, 30 September 2012 at 10:39 PM

I think the changes you made are a big improvement.

As for how your images look on other monitors, I have the opposite problem: my monitor is high gamut, so when I make an image look the way I want, it often looks too dark to other people and they miss many of the details that I can see clearly. There's really nothing I can do about it, except to use two monitors and test it on the regular monitor to make sure it's still acceptable.

Another issue with color perception is what kind of color profile you're using in your graphics editor when you do postwork. If you're saving your finished images with an embedded color profile, this may or may not be visible in someone else's browser. So when you save an image in Photoshop for the web, for instance, it's recommended that you choose the 'save for web and devices' and check the 'convert to sRGB' option (which is what is used in most browsers). This is quite different from the advice given for actually printing the images.


PoserPro 2014, PS CS5.5 Ext, Nikon D300. Win 8, i7-4770 @ 3.4 GHz, AMD Radeon 8570, 12 GB RAM.


hborre ( ) posted Sun, 30 September 2012 at 10:39 PM

Now you need a good skydome (BB's Envsphere) and IDL lighting to complete the effect.  The only thing that is truly lacking on this beast is SSS.  Snarly's EZSkin can provide those necessary nodes as well as the controls to modify and enhance node effects.  It beats having to manually change all the material zones, and it correctly provides the node structures which optimizes good shader responses to the lighting environment.


piccolo_909 ( ) posted Mon, 01 October 2012 at 3:54 AM

moriador: Yeah, i didn't even think about compatibility until someone mentioned to me that the werewolf in one of my test renders looked washed out on his screen. I thought that was a bit weird because it looked completely fine on my monitor. After some testing, i saw that with this model, something was giving it an "ambient glow" when i used gamma correction. If i turned the brightness up, the werewolf looked more and more washed up. This meant anyone who has a higher brightness setting than me will see a worse render rather than what i intended. Everyones suggestions helped a lot, and bagginsbill's showed one of the main culprits: the transluscence had to be turned off since that also gives a glow.

I'm guessing that what happened was this model was made a long time ago before gamma correction, and was expected to be rendered without it. Usually non-GC renders tend to be a lot darker in areas, and to make up for that, the maker added the glow with translucence. That worked perfect with no GC, but when GC is ticked on, it adds the glow as well as the GC which makes it him look like he has an ambient glow to it.

hborre: Yeah, i'm not sure what lighting i'm going to be using yet. With indirect lighting, i always have GC ticked off though, so all the ambient glow problem wouldn't exist. I'll test out ezskin to see how it looks on him. The thing i like so much about poser is there's so many options giving me lots of choices to make.

Thanks for the help guys, i learned a LOT from this thread ^_^


hborre ( ) posted Mon, 01 October 2012 at 11:24 AM

Glad you got something out of this.  Unfortunately, the Poser market is flooded with bad shaders/textures and settings which literally means each model and character must be evaluated in the MAT Room before actually committing to render.  That is where a consistent workflow helps to iron out those culprits and get you on your way to creating something worthwhile.


piccolo_909 ( ) posted Mon, 01 October 2012 at 11:59 AM

hborre: Yeah man. In my early days, i thought once i figured something out, it was done. However, i came to realize that every render was going to be different, because every texture, material room, model reacted differently, so it's basically a constant learning experience. It's fun though ^_^ I wanna thank you for taking the time to help me out too. Every problem i encounter, i learn like 10 new things from you guys helping me trying to solve it. The learning curve is insane, even for casual poser users like myself =P


modus0 ( ) posted Mon, 01 October 2012 at 2:33 PM

Quote - Ok, i unchecked reflection_lite_mult, and reduced the diffuse value to .85. I also upped the specularity a bit to 1.50 to make him a bit shiny. I also used the changegamma script that comes built in PP2012 and set the gamma's to 1 for the above mentioned maps.

You didn't use the script to change the diffuse did you? Because (unless I'm wrong) that would negate the effects of gamma correction on the textures.

________________________________________________________________

If you're joking that's just cruel, but if you're being sarcastic, that's even worse.


piccolo_909 ( ) posted Mon, 01 October 2012 at 2:51 PM

modus0: Naw, the diffuse was kept at 2.2, while all the other maps were set to 1.


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