LWF Again

[MikeeMax]

So I'm still in the process of learning how to use LWF. and I think I'm not there yet.
Since everyone makes his own cook, I think this would be interesting to compare each different setup you adopted.

basically, I think the most important part is the colour mapping panel.
i use exponential mode. dark 1 bright .454 gamma 1.
lwf not checked.
I render in max vfb.
all settings in 3ds Max gamma/LUT are set to 2.2.

after seeing my results, I think this is not correct.

what do you guys use for colour mapping modes?
Give some examples of you respective LWF settings.

[jacksc02]

linear 1,1 gamma 2.2

[MikeeMax]

tx for answering
max frame buffer or vray vfb ?
Max Gamma LUT 2.2 everywhere ?

[rmejia]

Don't know if you saw this recent thread over in the new RT section; it has info on setting up LWF:
http://www.chaosgroup.com/forums/vbu...ad.php?t=45790

[MikeeMax]

very instructive thread thanks rmejia

[MikeeMax]

i'm using those settings for LWF
Gamma & LUT Preference settings:
1) Enable Gamma/Lut Correction.
2) Gamma 2.2
3) Affect Material Editor
4) Input Gamma: 2.2
5) Output Gamma: 1.0

Vray Settings:
1) Max FB: off
2) Vray FB: on
3) Dark Multiplier: 1.0
4) Bright Multiplier: 1.0
5) Gamma: 2.2
6) Affect Background: checked


should i check the Linear workflow checkbox ?
when i check it, image look very dark.

lwf checkbox is meant to apply inverse 2.2 correction to the image. because in general images are 2.2 corrected. it means they have a 2.2 profile embedded. which is the case for most of the images which are in sRGB profile. so logically i should correct all my input images so the 2.2 profile is removed. this is done by the input images 2.2 parameters in the max gammaLUT panel.
if i check lwf checkbox in color mapping, it will apply another inverse gamma correction. so twice inverse corrected textures . not good. so it seems i don't have to check it, right ?

same goes for the colors. it seems it is not necessary to check lwf at all finally.

but if vray VFB and vray in general ignores totally the gamma/LUT display panel settings, then i have to check this box.
that's where i'm asking myself the question. does the vray vfb ignore the 3ds max gamma lut settings for textures input and output, or not ?

and since all the input images are gamma corrected to remove the 2.2 embedded profile, we can say they are "linear". So why the hell should we put the gamma parameter of vray color mapping to 2.2 ? indeed, the 2.2 valus will correct all the colors during the computation, as if they were not already inverse corrected, right ? but we just invert corrected the textures with the max gammaLUT input value !!!! so verything is linear ! why vray should be aware of any gamma thing since we put the right input values ?

this is a big sea of uncertainty for me....

[rmejia]

i'm using those settings for LWF
Gamma & LUT Preference settings:
1) Enable Gamma/Lut Correction.
2) Gamma 2.2
3) Affect Material Editor
4) Input Gamma: 2.2
5) Output Gamma: 1.0

Vray Settings:
1) Max FB: off
2) Vray FB: on
3) Dark Multiplier: 1.0
4) Bright Multiplier: 1.0
5) Gamma: 2.2
6) Affect Background: checked


should i check the Linear workflow checkbox ?
No


lwf checkbox is meant to apply inverse 2.2 correction to the image. because in general images are 2.2 corrected. it means they have a 2.2 profile embedded. which is the case for most of the images which are in sRGB profile. so logically i should correct all my input images so the 2.2 profile is removed. this is done by the input images 2.2 parameters in the max gammaLUT panel.
Yes

if i check lwf checkbox in color mapping, it will apply another inverse gamma correction. so twice inverse corrected textures . not good. so it seems i don't have to check it, right ?
Right

same goes for the colors. it seems it is not necessary to check lwf at all finally.
It's one or the other, but not both. Preferably use the Max settings. From the help:
http://www.spot3d.com/vray/help/150S...lormapping.htm
Linear workflow - when this option is checked V-Ray will automatically apply the inverse of the Gamma correction that you have set in the GammaVRayMtl materials in your scene. Note that this option is intended to be used only for quickly converting old scenes which are not set up with proper linear workflow in mind. This option is not a replacement for proper linear workflow.



but if vray VFB and vray in general ignores totally the gamma/LUT display panel settings, then i have to check this box.
They don't ignore it, they use these settings when displaying the image, but not when calculating the lighting.

that's where i'm asking myself the question. does the vray vfb ignore the 3ds max gamma lut settings for textures input and output, or not ?
No, the V-Ray fb does not ignore the lut settings for textures. It uses the Max settings.

and since all the input images are gamma corrected to remove the 2.2 embedded profile, we can say they are "linear". So why the hell should we put the gamma parameter of vray color mapping to 2.2 ?
There are a couple of ways of doing it, either in the VRay color mapping or in the Max settings. In the max settings it only brightens the image at the end. In the VRay settings it calculates the image using 2.2 gamma so it samples dark areas better.

indeed, the 2.2 valus will correct all the colors during the computation, as if they were not already inverse corrected, right ?
Which 2.2 values?

but we just invert corrected the textures with the max gammaLUT input value !!!! so verything is linear ! why vray should be aware of any gamma thing since we put the right input values ?
The textures are converted, but the way V-Ray calculates the lighting is not. The max gamma settings apply the gamma correction, but it's just brightening the image. It's like taking a 1.0 image to photoshop and applying a gamma 2.2, it will brighten the image but dark areas will have artifacts, because there is no information there to show when brightening the image. To have better sampling or more information in those dark areas, the image has to be rendered using gamma 2.2 so it looks good when it is brightened afterward.

Try out rendering an image with a lot of shadows and you will see the difference when using gamma 2.2 settings in VRay vs just using them in Max. The settings have to be adjusted in both places. Max for the textures, VRay Color Mapping for the lighting.

[rmejia]

Don't know if you saw this one, but here is an old sticky post Vlado wrote about LWF in the tips sections:

More gamma stuff and linear workflows
http://www.chaosgroup.com/forums/vbu...ad.php?t=33917


edit: just saw you posted in that thread, never mind then

[MikeeMax]

i love you.

just to recapitulate and to get rid of my remaining doubts, the display and input max gammaLUT 2.2 value are not "redundant" with the vray color mapping gamma 2.2 value(right ?)
so the 2.2 display/input in max and the gamma 2.2 in vray color mapping seem to you to be a correct config, right ?

[MikeeMax]

thanks very much rmeja.
this is a damn good feeling to finally jump out of an intellectual mess about something.

[zeronove]

i love you.

just to recapitulate and to get rid of my remaining doubts, the display and input max gammaLUT 2.2 value are not "redundant" with the vray color mapping gamma 2.2 value(right ?)
so the 2.2 display/input in max and the gamma 2.2 in vray color mapping seem to you to be a correct config, right ?

IMHO, that's exactly the main source of misunderstanding with all the LWF thing!

The max gamma setting affects ONLY the MAX frame buffer; it DOESN'T affect the VRay Frame Buffer at all

So the answer to your question is YES, they are not "reduntant"

[MikeeMax]

ok for the max DISPLAY gamma settings, which acts only on max frame buffer.
but the max input gamma setting affect the textures,with both vfb or max frame buffer. right ?
that is why it is un necessary to check lwf checkbox, because that would correct the textures twice if i understoode correctly.

[MikeeMax]

as soon as i think i understood coorectly, another doubt comes to hit my head.
do

is the texture correction is made with the vray 2.2 color mapping gamma or with the max bitmap 2.2 gamma?
that would result in the same thing, but it's a important difference. if the texture gamma correction is made with vray 2.2 color mapping gamma, there is no need to set the bitmaps input gamma to 2.2.....
and if the texture correction when rendering in Vray frame buffer is not made by any of the two, then i have to check the damn lwf box....

loop until i understand.

[sv]

technically, you should have in the colour mapping:
linear, darks=1, lights=1, gamma=2.2 and have "don't affect colours adaptation only" enabled, you view the image in sRGB space within the Vray Frame Buffer, and save your files as .exr or .vrimg. If you do this, you have a linearly encoded file, which will be fine for doing re-compositing of the render elements. If you don't do this, and you bake the 2.2 gamma into the image, any re-compositing of elements WONT give correct results, as the file isn't linear data anymore; it's got a gamma curve baked into it....

[MikeeMax]

i tried your method, and with sRGB enabled, the results are quite the same in terms of colour/contrast....
what is the advantage of using this method when doing re-compositing of render elements ?? (or what problem can i meet when i'm not using it?) what do you mean when you say it WONT give correct results ?