LWF Confusing

[SteveC]

I'm not sure if this is the right place to post this, hopefully some of the
answers i get hear may help other also.

To all those who understand LWF, my appologies for not being able to
understand it\the massive confussion i seem to be having with the
answers given to other peoples questions.

I'm pretty certain that i'm not the only one on the forum who finds the
whole LWF thing very confusing, i dont know if this is because there has
been so many questions asked about it, or if its because I'm trying to
implement something in to my workflow that i just dont understand, or
maybe I'm just thick.

The reason for this thread is just to try and get some clarity on if i am
indeed working in LWF, if not, where am i going wrong, and to pose a few
questions that seem to have caused some of the confusion.

Firstly, my setting are as follows.

Monitors
They are all calibrated and set up to gamma 2.2

Photoshop
Is set to sRGB colour space

Max
In Customize\Preferences\Gamma & LUT
1. Enable Gamma & LUT= ON
2. Load Enable state with Max Files = ON
3. Display Gamma radial button selected and Gamma set to 2.2
3. Affect Color Selections= ON
4. Affect Material Editor= ON
5. Input Gamma= 1.0
6. Output Gamm= 1.0

With the above settings, I'm assuming that my system is now set up and
ready to work in LWF

Also with the above settings my material sample slots now look washed
out in the material editor, which lead me to the following questions.

QUESTION 1.
How do i stop the material sample slots from looking washed
out because any bitmaps i apply to a sample slot also look washed
out.

QUESTION 2.
Do i need to tweak any bitmaps in Photoshop first, that i wish to use as a
material in max

Bitmap Import Workflow

I'm writting this because, probably, like others i normally drag and drop
my bitmaps in to the diffuse slot of a material in the material editor, this
did have an effect on the way the bitmap was displayed in the editor slot,
it was washed out.

After some playing about and answers in a previous thread, my workflow
now for importing a bitmap in to the diffuse slot of a material is to click
the diffuse slot and use the "Select Bitmap Image File" interface,
Once I select a bitmap, I overide the bitmaps gamma, to 2.2, in the
interface and the bitmap now displays correctly in the material editor slot
and also renders correctly.

QUESTION
Am i using the correct workflow by overiding and tweaking the bitmaps
gamma to 2.2 in the "select bitmap image file"

Colour mapping
The colour mapping i have left set to Linear Multiply
Dark Multiplier= 1.0
Bright Multiplier= 1.0
Clamp Output= Unchecked

QUESTION
Are these setting correct for LWF

Rendering
I now render to the vray frame buffer, the renders look great. If i
renders in the default max buffer the renders still look washed out.

QUESTION
Is this correct, should the same scene look different when rendered in
the vray frame buffer and the default max buffer

Using the above settings, material import method and Color mapping,
I have to say that there is a very noticable difference to my simple test
scene, I cant quiet put my finger on it, if its the lighting or the materials.

Going on this basis i can only assume that i am now working in LWF

I would be greatfull if someone who knows better could point out any
areas where i am messing up, I think i've got it right, but cos of all the
confusion i'd like a second opinion.

I also hope that any answers\info hear helps other that are also confused
with this whole LWF thing.

sorry for the long post

cheers
steve

[ene.xis]

Re: LWF Confusing

OK...here goes...
i m no expert in the subject, but i think i can grasp it, and i got results that make me feel confident about it...
so....

Monitors
They are all calibrated and set up to gamma 2.2
steve

ok, they don t have to be set up to 2.2, u have to find the correct callibration value for each monitor, because they may vary....

Max

5. Input Gamma= 1.0

u have to bump this to 2.2, so the bitmaps u load have the linear curve reversed...

QUESTION 2.
Do i need to tweak any bitmaps in Photoshop first, that i wish to use as a
material in max

not necessarly. and if it doesn t look right u can correct within max either with the bitmaploader or with the colorcorrect plugin....

After some playing about and answers in a previous thread, my workflow
now for importing a bitmap in to the diffuse slot of a material is to click
the diffuse slot and use the "Select Bitmap Image File" interface,
Once I select a bitmap, I overide the bitmaps gamma, to 2.2, in the
interface and the bitmap now displays correctly in the material editor slot
and also renders correctly.

this is because u didnt change the bitmap input gamma in the max preferences to 2.2!

Rendering
I now render to the vray frame buffer, the renders look great. If i
renders in the default max buffer the renders still look washed out.

if it looks great on vrayframebuffer without either:
1. aplying throb s linear curve to the colors correction in vray framebufer
2. using gamma correction in the color maping set to 1 - 0.4545
u have to redo ur light values and balance...u see the thing is in linear u can realy save render time cause u dont need so much light in the scenes.
hope it make some sense...
i know there are will be more questions....but i m tired of typing!hehehe

[SteveC]

ene, thanks for your time and patience, i owe you one. I think we
cracked it

I did your suggested tweak to the input gamma and set it to 2.2, now the
bitmaps come in to the diffuse slot without needing any tweakery and the
material slot looks good, not washed out or anything.

I also used the gamma correct setting 1, 0.45454 and you're right, when
i did the render the light did need turning down, i reduced the light
intensity to 0.4 and this was still too bright, would be better at about 0.2
maybe 0.3.

I also did the same render to the max buffer and this was very washed
out, although when i viewed the vray buffer render and the max buffer
render in photoshop they both looked identical.

Does this sound right to you, please say yes

many thanks
steve

[ene.xis]

ene, thanks for your time and patience, i owe you one. I think we
cracked it

never mind that...i love this forum and most of all i m glad u r getting it cracked

I also did the same render to the max buffer and this was very washed
out, although when i viewed the vray buffer render and the max buffer
render in photoshop they both looked identical.

Does this sound right to you, please say yes

that s absolutely right! u see max framebuffer double corrects the color curve.
now forget entirely the max framebuffer and skip to vray framebuffer s power

and now the real deal:
u have to work either 1) keep in linear with color maping set to linear 1 / 1 save ur render to exr or hdr (i m now using exr and i love it), or 2)burn the gamma to the render aplying the gamma color correction 1 /0.4545

i ve been using the second for a while now, but lately, and after running some tests i ve switched for the first and keep everything linear untill the post! i save the render to exr open it in photoshop and just do some minor corrections as it automaticly loads the correct gamma with it

let me know how that works for u!

[SteveC]

Excellent, at last it feels like i'm making headway

I'm not sure i understand what you mean by the following though

[/quote]
and now the real deal:
u have to work either 1) keep in linear with color maping set to linear 1 /
1 save ur render to exr or hdr (i m now using exr and i love it), or 2)burn
the gamma to the render aplying the gamma color correction 1 /0.4545
[/quote]

does that mean that i have to either

1. change my colour correct settings to linear 1/1 now, for any further
renders i wish to do or
2. stick with the method i've just used and burn in the gamma 1/0.45454.

In method 1, I did a test render and the render came out darker, but
opened in PS and was ok, this way seems a bit strange because you only
see the true image when you open it in PS. Is that correct

In method 2, Would i just keep gamma 1/0.45454 in colour mapping,
render as normal and then just save this render as .exr

thanks
steve

[ene.xis]

well that s real the crutial thing u see...
in 1 u keep all the workflow in linear untill post production, while in 2 its a shortcut were u ll might loose some of it....there are pro s an contr that have allready been stated some where in one of these threads....

In method 1, I did a test render and the render came out darker, but
opened in PS and was ok, this way seems a bit strange because you only
see the true image when you open it in PS. Is that correct

that s it ....and well u can check it during render by just correct the color curve in the vray frame buffer....

[ene.xis]

Not sure what you are doing here. Is this a scene or is it a BG image you're rendering?

There are 3 ways of getting gamma correction:

1. use gamma color mapping as said
2. don't use it and apply throbs curve to the vray frame buffer so your image looks correct in the VrayFB
3. don't use vray frame buffer. The max frame buffer is gamma 2.2 corrected because of the display settings so your image will look correct(vray frame buffer isn't affected by the display gamma settings!)

The difference between 1 vs 2 and 3 is that in 1 the gamma 2.2 is burned in. In 2 and 3 it is not and if you open that image in photoshop, you need to apply a correct profile to it otherwise it will look very dark.

This also means that in 2 and 3, the image isn't gamma corrected at rendertime (it is done in the viewing system: throb curve, max display gamma, PS color profile). So it is in fact a pretty dark image. Vray will sample dark areas not so good, resulting in bad AA for example.

This image was created with option3:



This one is the same, but rendered with the vray vfb and gamma color mapping (1/0.455). (option 1)


Notice the difference in AA quality!

The first one rendered faster though, because vray didn't sample that much. So if you use option 2 or 3, you need to increase the QMC sampler settings to get clean enough AA.

[SteveC]

Great work, I'm not sure which method i'm going to go with yet, I think a
bit more time experimenting with each of the methods until i find which
one seem more intuative to me.

There is a slight difference between my 2 test scenes, as there is with
yours, when using the 2 different methods, I do think the linear 1/1
render looks slightly better than the gamma correct version.

I'll do a search for throbs curve thingy, i'd like to stick with the vray buffer
and linear correct version if i can, but i would like to use throbs curve so i can see what i'm rendering.

cheers ene, you've helped me a lot

steve

[ene.xis]

glad to hear that....just keep it coming

[vlado]

This also means that in 2 and 3, the image isn't gamma corrected at rendertime (it is done in the viewing system: throb curve, max display gamma, PS color profile). So it is in fact a pretty dark image. Vray will sample dark areas not so good, resulting in bad AA for example.

Yes, BUT, your monitor (if calibrated correctly) will darken those areas again later on, so the bad AA will not be visible. In that case, it will be a waste of render time to make V-Ray take more samples when they will not be apparent.

Best regards,
Vlado

[3ddesign]

SteveC wrote:

Monitors
They are all calibrated and set up to gamma 2.2
steve

ok, they don t have to be set up to 2.2, u have to find the correct callibration value for each monitor, because they may vary....

Ene.xis,

I think your answer here is wrong. You calibrate your monitor to the workflow you plan to use (refer to Vlado's post here: http://www.chaosgroup.com/forum/phpB...b96c6ee74aa0d3 ).
If you plan to use workflow or method 2, you calibrate to 2.2. If you use method 3, you calibrate it to 1.0

SteveC wrote:

Max

5. Input Gamma= 1.0

u have to bump this to 2.2, so the bitmaps u load have the linear curve reversed...

This depends on how the bitmaps were created. If they have the gamma 2.2 applied either by the digital camera, the scanner or in PhotoShop, you need to check 2.2 or use the 2.2 override in the Select Bitmap dialog box. Some people keep all their bitmaps linear (either by setting the scanner to 1.0 output, using a RAW digital image without a 2.2 color profile, etc.) in which case you click 1.0 or use 1.0 override in the Select Bitmap dialog.

SteveC wrote:

QUESTION 2.
Do i need to tweak any bitmaps in Photoshop first, that i wish to use as a
material in max

not necessarly. and if it doesn t look right u can correct within max either with the bitmaploader or with the colorcorrect plugin....

If your monitor is calibrated properly, you understand color management in PhotoShop and use one of the methods described by Vlado (link above) then the bitmap you see in PhotoShop should be very close to what you see in Max's Material Editor and in the final render (taking in account the lighting and environment of your 3D scene). Thus, it is a very good idea to tweak your bitmaps in PhotoShop.

SteveC wrote:

Rendering
I now render to the vray frame buffer, the renders look great. If i
renders in the default max buffer the renders still look washed out.

If you have everything set up as Vlado mentions, render using Linear Multiply, 1,1 then you should see your image correctly in the Max Frame Buffer. If you don't its because your lighting needs to be corrected.

I also did the same render to the max buffer and this was very washed
out, although when i viewed the vray buffer render and the max buffer
render in photoshop they both looked identical.

This will depend on the profile you assign when loading it into PhotoShop. I really suggest reading up on Color Management in PhotoShop and implementing a good Color Management workflow. Without understanding this, you will always be confused at the way the various renders and frame buffers behave when bringing images into PhotoShop.

Ene.xis says you have to use EXR if you render linear 1,1. While EXR is a great format, you can still use 8 bit TIFF images and get great results. It all depends on what your target output device is.

I'll do a search for throbs curve thingy, i'd like to stick with the vray buffer
and linear correct version if i can, but i would like to use throbs curve so i can see what i'm rendering.

I'd be careful when using throbs curve. I've found that .64 is not accurate, .61 gives me more accurate results. Anyway, all you're doing with the curve is compensating for the inability of the Vray frame buffer to respond to the Enable 2.2 Gamma in your Max Preferences. Your rendered image remains the same no matter what frame buffer you view it in. If all you are doing is bringing it into PhotoShop, the critical thing is the Gamma Output Setting used in Max Preferences (or the Override Gamma seeting in the Image Save dialog box) and the color profile you assign the image when loading it into PhotoShop (only enabled if you are using Color Management).

Craig

[ene.xis]

Ene.xis says you have to use EXR if you render linear 1,1. While EXR is a great format, you can still use 8 bit TIFF images and get great results. It all depends on what your target output device is.

if ur going linear till the post production fase the only benefict u got is from the 32 bits files saving all the information contained in the linear process....
if ur going 8 bit, theres no point in going linear...just burn the color correction in the picture during render with gamma correction...

Craig...i think u should carefully review ur post...ur mixing up hardware calibration with software....nevertheless i think u should re-read some of the LWF concepts there...

[SteveC]

Thanks for all the replies chaps, all the threads on this topic have been a
great help, but also a major source of confussion due to the amount of
differing info out there.

The reason i started this thread was in the hope of getting simple straight
forward answers from one person, which i did, ene, without your help i
doubt i would have come to grips with the whole LWF thing the
difference in the quality of the lighting and the renders as a whole make
the whole struggle with trying to learn this very worth while.

I think what is needed on this subject is a single definative document,
for the 3 methods outlined by vlado, with each method having its pros
and cons highlighted, and where each method would best be used. Each
method should then have a full set of instructions to walk people though
setting up their monitors, photoshop, max and vray.

The thread should then be locked so no alternatives or suggestions can
be added, this is what i found very confusing, i would read up on a method
of LWF, but then the following posts would throw doubt or additional
suggestions in, making it very confussing.

Perhaps those with a greater knowledge of LWF than i have, could get
their heads together a formulate such a document it's only a
suggestion, but i think it will help a lot of people.

Cheers
steve

[3ddesign]

Ene.xis says you have to use EXR if you render linear 1,1. While EXR is a great format, you can still use 8 bit TIFF images and get great results. It all depends on what your target output device is.

if ur going linear till the post production fase the only benefict u got is from the 32 bits files saving all the information contained in the linear process....
if ur going 8 bit, theres no point in going linear...just burn the color correction in the picture during render with gamma correction...

Craig...i think u should carefully review ur post...ur mixing up hardware calibration with software....nevertheless i think u should re-read some of the LWF concepts there...

Maybe I'm completely off base here. I've made several posts and I hope I'm not leading people astray. But I've made many tests using all the methods outlined in the varios LWF threads and have posted my findings. For example, I've tested linear renderings using EXR, linear renderings using 8 bit TIFFs and burned in color correction with gamma correction. In the workflow I've defined in my tutorial thread, I go directly from Max to PhotoShop and then to Monitor output or Printer output. Given this workflow, I've found that rendering in linear gives me more accurate color results than using gamma correction*. And since my scenes are built accurately, I have to do very little manipulation in PhotoShop. Thus, I've never seen any difference in EXR vs. TIFF.

Now having said that, I have no ego to protect here. If I am off base, I hope people will let me know. Just stating that I need to go back and re-read LWF concepts is not very productive. Let me know where I'm wrong and why. I come to this forum to learn as much as I can. I can't learn if I'm not told where I'm messing up.

(*For the method I've used to test the various methods, see http://www.chaosgroup.com/forum/phpB...9a6ea6bf8b12f5 . I assume that using raw LAB or RGB numbers and a IT8 color target is a good way to test accuracy. If I can get the color numbers going into my render to match the numbers coming out, I would think this indicates accuracy. If I'm wrong, I sure hope someone will tell me. )

[ene.xis]

I come to this forum to learn as much as I can.

we all do!

u don t see any difference due to ur workflow...as i recall i was adressing Steve to a specific workflow when i mentionned the diference between 8bit tiff an d 32bit exr...