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tcoursey
03-29-2012, 02:26 PM
Can someone explain the "proper" use of linear color space. I know thats a far reaching subject and has many different interpretations possibly.

Do you set your color picker to Linear?
What about images that are probably already corrected (aren't most images?)
Save in Linear or sRGB?

Thanks for any clarification.

mis
03-29-2012, 03:11 PM
you will here find some deeper explanation
and video
on how and why to use this . :)

and trust me its worth it, especialy if you are working on rendering archi stuff

http://forums.newtek.com/showthread.php?t=102397&highlight=linear+workflow

XswampyX
03-29-2012, 03:28 PM
I'll have a stab. :)

Think of LW as a Linear colour space factory. (LCS)

LCS (texture image/colour) -> Lightwave -> LCS image (render). -> LCS Display on screen. If you only had LCS textures and a monitor capable of displaying the full range of LCS then this would look fantastic. but you don't!

Sol, what's the problem? :D

Most images on the internet are sRGB, or to put it another way, images that have been 'converted' to be displayed on your average monitor. So you have to tell LW what 'colourspace' your source image is in. sRGB (most of them) or LCS.

So back to the factory....

sRGB (image ColourSpace) -> internal LW conversion to LCS -> Lightwave -> LCS image (render) -> display on monitor.

So good so far..... "But my render still looks like dark 'n' stuff?"

To 'see' the render in it's full glory you have to do another conversion after the render to display it on your (sRGB) monitor.

So back to the factory....

sRGB (textures etc) -> internal LW conversion to LCS -> Lightwave -> LCS image (render) -> internal LW conversion to sRGB -> display on monitor. :thumbsup:

That's it.....

The thing is the LCS render; before you convert it to sRGB has tons of extra colour info in it, more than your monitor can display. When you convert it using lightwave you could be throwing away loads of useful information that would be used by other programs (photomatix for one) and using that information wisely will make all the difference to your renders. There's nothing wrong with LW's conversion, it's a one size fits all, but If you wait 2 hours for a render I would save as much info as I could.

Now I'm confused! :hey:

RebelHill
03-30-2012, 03:17 AM
tbh, u can forget the explanations... just use the srgb preset.

bazsa73
03-30-2012, 03:30 AM
tbh, u can forget the explanations... Just use the srgb preset.
+1

RebelHill
03-30-2012, 03:59 AM
The thing is the LCS render; before you convert it to sRGB has tons of extra colour info in it, more than your monitor can display.

Not true Im afraid.

Linear or Log spaces (srgb being a log) contain no more or less information than one another. You're getting confused with dynamic range/bit depth.

speismonqui
03-30-2012, 03:05 PM
so the best thing to do would be just to use the sRGB preset.

how does this work IF I'm using an external compositor/finnishing system (AE, Fusion, PS, Nuke)? In this case would it be better to use the Linear preset?

Now I'm still confused! :)

stiff paper
03-30-2012, 03:24 PM
how does this work IF I'm using an external compositor/finnishing system (AE, Fusion, PS, Nuke)? In this case would it be better to use the Linear preset?

If you want linear, select sRGB, and if you want sRGB, select linear. Perfectly intuitive, isn't it? Nothing whatsoever wrong with that as a smart bit of interface design.

...oh wait... yeah, that's right. It's the most simplistic, basic, fundamental and easily avoided interface design error one could ever commit... selecting the specific opposite to what you actually want to select.

I simply can't understand why you're confused at all.

stiff paper
03-30-2012, 03:31 PM
Ahem. Selecting "sRGB" makes LW work in linear.

If you save out your renders as exrs, then Nuke ususally decides the images are linear when you import them. Sometimes Nuke doesn't realize what's going on, especially if you've got an unexpected gamma on an image, but you can change what Nuke thinks the image's gamma is in the loader.

Most things seem to "expect" extended range images to be linear and everything else to be sRGB. Don't know exactly what you do in the other packages you mention, but I'd be surprised if it wasn't similar to Nuke.

dwburman
03-30-2012, 03:45 PM
LightWave always works in linear space. Selecting sRGB does not put LightWave into linear mode.

sRGB mode says "My inputs are all/mostly using the sRGB gamma space, so correct their gamma before rendering them"

Linear mode says "My inputs are already corrected to linear space, so do not apply any gamma corrections to them" - Of course, if your images/inputs are not corrected to linear space, you'll need to tweak lighting/etc to make sure they look okay, which is the same thing we did before we had the Linear Color Space tools.

Cageman
03-30-2012, 04:15 PM
If you want linear, select sRGB, and if you want sRGB, select linear. Perfectly intuitive, isn't it? Nothing whatsoever wrong with that as a smart bit of interface design.

It is quite intuitive if you actually read the labels and text in the CS-tab.

"Convert Color Space to Linear", Color Space, in this case refers to your inputs (textures, lights etc).

The thing that people seem to miss here, is that LWs renderengine is allways operating in Linear space. There is no way around that. So, you tell LightWave that your textures, lights etc are in sRGB space (or whatever LUT you might be working with), so that LW can convert it into Linear space in order to feed the renderengine with proper data.

Pretty straightforward, imho.

EDIT: dwburman actually posted the same thing I did, I see now... haha. :)

Tobian
03-30-2012, 09:17 PM
I would pretty RebelHill too, just use the SRGB but with a few caveats.

Only colour textures should be set to be 'srgb' as per the preset. Greyscale textures, such as should be used for spec, diffuse or bump should be tweaked to be Linear only (go into the image editor and set them from 'default' to Linear). Same goes for any normal maps, as these will not function very well if you apply CS operations to them! :)

And Cardboard, yeah, it is slightly counterintuitive, but it's going to confuse someone at some point either way. The point is, as others have said, that Lightwave always had worked in Linear, it's just the colours fed into it were in sRGB, which created inaccurate results. We also didn't have a correct way to view Linear renderings, before LW10, so that further confused the matter :)

speismonqui, if you're working an external app, you would still work with the srgb profile, as a rule, I do. If you're working with non-srgb source footage, such as a rec709 video footage, then likewise use that preset. The important thing is to get LW to convert everything into Linear colour space before it does the rendering, so that when previewed either in LW or other apps, it will be correctly displayed. I don't know about Nuke, but by default AE will apply a sRGB display gamma to files which are saved in float formats (such as EXR) because it assumes they will be stored with a linear colour space. Altering the display colour-space in LightWave doesn't 'bake in' the colour (such as when you used to use FPGamma 2.2 to alter the way the image was displayed),all it does is approximate how those images will be displayed on other sRGB apps. The simplest answer though is.. use the sRGB preset, load it into your compositing app, and if it looks fine, then it's working :) the only caveat there is of course if it applies a display gammut, or you need to manually add one (as mentioned AE does by default).

speismonqui
03-31-2012, 04:43 PM
thanks a lot Tobian, and of course everyone else.

bonobo9
05-30-2012, 03:37 AM
How can i dot it with LW 9.6???

geo_n
05-30-2012, 05:35 AM
How can i dot it with LW 9.6???

http://www2.informatik.hu-berlin.de/~goetsch/CCTools/

gerardstrada
05-31-2012, 07:30 PM
SG_CCTools (http://www2.informatik.hu-berlin.de/~goetsch/CCTools/) still works in LW 11, btw. It doesn't apply automatically and has some things to enhance, but it's far more advanced and powerful than native implementation. It allows for more accurate previews, allows us to work in real scene-referred spaces and we can even preview CMYK colors (http://forums.newtek.com/showthread.php?p=1243952#post1243952)! Both systems (SG_CCTools (http://www2.informatik.hu-berlin.de/~goetsch/CCTools/) and native LW CS) can be used together as well, there's even a trick to have SG_CCTools (http://www2.informatik.hu-berlin.de/~goetsch/CCTools/) working in VPR.



Gerardo