VRay Framebuffer vs Max Standard Framebuffer

[Cascho75]

Hello,

I´m very new to VRay and was wondering that my renderings mostly look very washed out.
Then I tried the VRay-framebuffer and here the images look better, have much more contrast.

When I

clone the framebuffer to Max framebuffer
or I save to 48 bit
or I switch to sRGB

I get that bad washed out result again.

Why?

[rmejia]

That might be the way things look with Gamma 2.2, adding contrast or applying curves in Photoshop afterwards helps. Also what settings are you using for Gamma 2.2, are you correcting your bitmaps?

[Cascho75]

Hmm, to be honest, I don´tknow much about gamma.
When is it useful to enable gamma correction?
Here are my settings:


I don´t prepare my texturemaps, should I?
If yes, how? I have PS CS4.

After all I always try to get best results in the original rendering and do postprocessing as less as possible.

[rmejia]

You should have 2,2 instead of 2,69

The higher that number the more washed out the image will be. 2.2 is the standard, or 1.8 in macs. Also check both boxes in Materials and Colors. Putting the Bitmap Files Input to 2,2 adjusts the gamma on the texturemaps.

There are some long threads and battles around the forum about Gamma
http://www.chaosgroup.com/forums/vbu...ighlight=gamma
http://www.aversis.be/tutorials/vray...l_gamma_01.htm

[Cascho75]

But, Max Help says I have to adjust that grey box so that it has minimum contrast to its surrounding field.
This is the case at 2,69 on my screen.
Next thing the Helps says is that then I have to set the Bitmap output gamma to 2,69.

By the way I have an LCD Flatpanel....

[rmejia]

I think the monitor should be calibrated, rather than adjusting the Gamma from 2.2. I have flat panel monitors and use a Datacolor Spyder to calibrate it. 2.2 is a very specific number and sRGB is very close to 2.2. It is the standard Gamma Correction curve for LCD's. http://en.wikipedia.org/wiki/Gamma_correction

The explanations can be very extensive, a couple of pages long, in summary 2.2 is the magic number. Digital cameras use 2.2 and so does Photoshop. If the grays don't match up, the monitor should be calibrated so they do. If you save it only for your monitor at 2.69 and view the image in another monitor the gamma will look different. When the help mentions that the gamma you choose can vary depending on the monitor, I believe they are referring to the difference between LCD and CRT monitors. CRT use different settings.

[Cascho75]

Ok, I see I have to get deeper into it....
Thank you very much!

PS:
Is it "allowed" to decrease the secondary bounces multiplicator to e.g. 0.7 to get more contrast in my interieur scene?

[rmejia]

Yeah it can get very technical. Gamma became a huge issue when people started using it and generated a lot of confusion and anger. There have been several articles written about it. Hopefully you can find some to clear everything up.

My workflow is to calibrate the monitors, set Gamma 2.2 in Max, activate the sRGB button in the V-Ray frame buffer and in the V-Ray Color mapping settings I set Gamma to 2.2 and check the "Don't affect colors (adaptation only)" checkbox, using Linear multiply as the Type.

[rmejia]

PS:
Is it "allowed" to decrease the secondary bounces multiplicator to e.g. 0.7 to get more contrast in my interieur scene?

Sure, you can lower it as you like. I actually use .9 often in the Secondary bounces with Light Cache.

[Cascho75]

I asked because VRay Help says that 1.0 is physically correct.

[rmejia]

After all I always try to get best results in the original rendering and do postprocessing as less as possible.

Unless it's an animation, I like to do ALOT of post processing in for stills in Photoshop

It's amazing what you can do with Photoshop, I love Photoshop !

[rmejia]

I asked because VRay Help says that 1.0 is physically correct.

Yep, 1.0 it is physically correct. Whether things should only be physically correct, like Gamma, also has different opinions and sides. I don't mind faking it when needed, it's all about how it looks in the end. A great thing to me about V-Ray is that it is flexible in that aspect and gives the user the option to chose.

[Cascho75]

I still don´t understand what exactly is the difference between saving the rendering with sRGB enabled or not.

Renderings with sRGB look so washed out to me.

[rmejia]

It makes a big difference when setting up the lighting for a scene. Could you post your images to see how washed out they look?

Here is a link to another tutorial:
http://renderstuff.com/free-3d-tutor...2.2.php?page=3

[Cascho75]

Upper image is with sRGB enabled, too les contrast for my taste.
Secondary bounces multiplier is 0.7 !




Next thing I don´t understand is, sometimes I can not save the darker non sRGB version to disk, it´s automtically converted to sRGB then. This seems to happen randomly.