Linear workflow wrong?

[sharktacos]

Washout how so? Diffuse textures or lighting in general? If its lighting, well.. welcome to linear workflow. That's the whole point of using linear workflow for lighting.

Metzger your posts always crack me up (I mean that in a good way )
To clarify, the point would be that the lights actually behave properly with linear workflow, so if you switch over, the old lights will look broken (washed out) because they are. You need to re-do the lights. The final image should look good of course, not washed out.

I'm sure you know this, but I can't tell you how many students I've encountered who think that linear lighting is supposed to look washed out, as if that were a good thing. If it doesn't look good, it isn't good.

[snivlem]

Washout how so? Diffuse textures or lighting in general? If its lighting, well.. welcome to linear workflow. That's the whole point of using linear workflow for lighting. You need to adjust your lighting. If your textures are washed out, are you using 8bit images and applying a vray gamma input node? Are you using exrs? If so you probably have a double lut happening with the exr having an srgb gamma included in the file which is wrong. I use Maya 2009 so I don't mess with the new color management in Maya 2011. Post a zip with textures and a scene file. I will check it out for ya.

Yeah mate, I can use the workflow perfectly with mental ray and linear workflow I understand it. But there is something doubling up in my V-Ray workflow as everything is washed out. I haven't dived in too deep as I'm in th emidlle of production but I just use the tickbox approach - I still get paid for my images so I hadn't really thought about the "proper" way yet.

Will be able to post in more detail later. THanks for the help.

[sharktacos]

there is something doubling up in my V-Ray workflow as everything is washed out.

What do you have the color profile set to in the render view display?

[snivlem]

Hi sharktacos, sRGB both in the Image Color Profile and Display Color profile.

Is it right to have "convert to sRGB" and 2.2 in the vray render settings on?

[sharktacos]

Hi sharktacos, sRGB both in the Image Color Profile and Display Color profile.

That should be fine.

Is it right to have "convert to sRGB" and 2.2 in the vray render settings on?

Yes.
Did you read through how to set this up in the Nederhorst Primer? That should give you correct results. If you set up a new scene with a sphere with a color texture lit by a directional light, does that look washed out?

[pechart]

Wow, this issue will always stay on the first page of every CG forum I visit . I wrote some lines on this topic some time ago, maybe you want to step through this.

http://www.chaosgroup.com/forums/vbu...434#post443434

In addition i'd say: Don't use any of Mayas inbuild color profile tools, keep them at the default. Also i recommend using the vray framebuffer. In this, check the sRGB button. If you use the maya renderview instead you have to use the 'convert to sRGB for renderview' option.

[Fredrik Averpil]

Procedural textures are always linear.
Best regards,
Vlado

Vlado,
Is this V-Ray specific?

I'm pretty sure Maya's procedural textures are in gamma 2.2 colorspace and needs gamma correcting for linear workflow – but not if they are used for non-color properties such as bump, specular strength, reflectivity etc. Although maybe this is not the case when rendering using V-Ray?

[MoonDoggie]

I'm 99% sure any image created within the computer is already linear. Make a ms paint drawing? Linear. The same applies to all procedural textures as well.

[sharktacos]

I'm 99% sure any image created within the computer is already linear. Make a ms paint drawing? Linear. The same applies to all procedural textures as well.

I'll need to confirm this in Vray, but I can say with 100% certainty that in mental ray procedural textures applied to the color are not linear and do need gamma corrections. Consider the Leather Texture: it has 2 color swatches (cel color & crease color). In Maya the color management does not affect the color swatches and so they will be washed out when the image is displayed as sRGB. Vray has an option to "affect swatches" which adjusts for this, doing a gamma correction to the swatches in the same way that the "linear workflow" button does for the image maps. If the "affect swatches" was unchecked I believe you would have the same problem in Vray too.

Let me also add that the vray "affect swatches" does not work for the Shave & a Haircut hair swatch colors (in particular the root and tip colors). It would be good if this was corrected in a future update.

[snivlem]

Sharktacos, this was the problem I was having!

Vray has an option to "affect swatches" which adjusts for this, doing a gamma correction to the swatches in the same way that the "linear workflow" button does for the image maps.

That's where I was having problems with double the correction in my workflow - cheers!

[Metzger]

Affect swatches puts an sRGB viewer lut on your vray shaderball. I don't think it does anything more than that.

[sharktacos]

Affect swatches puts an sRGB viewer lut on your vray shaderball. I don't think it does anything more than that.

So I did a test (leather texture in diffuse color of vray material), and indeed the "affect swatches" does not affect the render. What does affect it is the "linear workflow" button. If it is checked, then colors (like the colors of the leather procedural texture) render correctly in linear. If it is not, then the colors from the procedural appear washed out because they need a degamma. So if one does not want to use the "linear workflow" button, they need to have degamma nodes on all their color inputs (not just on image maps), including, some things one might forget like, for example, the scatter color on the sss2 shader, or the tip color on hair.

[vlado]

Vlado,
Is this V-Ray specific?

Nope. It's the same for Maya software, hardware and mental ray renderers.

I'm pretty sure Maya's procedural textures are in gamma 2.2 colorspace and needs gamma correcting for linear workflow – but not if they are used for non-color properties such as bump, specular strength, reflectivity etc. Although maybe this is not the case when rendering using V-Ray?

They are linear in the physical space, but not in the perceptual one. I meant the first (physical space) since this is what a renderer works with, what you probably had in mind is the second (since this is what you see). A physically linear gradient doesn't look linear when you look at it (the middle gray doesn't look half as bright as full white). And vice versa, a gradient that looks linear to our eyes, is not linear in physical terms. Since Maya's textures are linear in physical terms, they don't look linear to you when viewing the output image with gamma correction - which is why you are applying the 2.2 gamma to them.

Best regards,
Vlado

[Fredrik Averpil]

I meant the first (physical space) since this is what a renderer works with, what you probably had in mind is the second (since this is what you see).

Thanks for the clarification, Vlado. Yeah we were talking separate things. Like you say, I was thinking about how Maya presents colors to us in the UI and how they are rendered out differently on screen when having the sRGB button enabled in the framebuffer for linear workflow. So for example, when entering a specific color code or choosing a color value using the color picker you also need to "de-gamma" that result using a gamma node before passing it into the shader in order to maintain that exact color – when working with the sRGB button enabled in the framebuffer for linear workflow, that is.

At least, that's why I "de-gamma" procedurals and colors that are meant for color attributes.

Wouldn't it be great if Maya just had a little option in the color picker which would show the "linear" (perceptually) color wheel and spectrum so that you could pick a color from that one instead – or when entering a color value it would allow you to "de-gamma" it right there?

[snivlem]

Wouldn't it be great if Maya just had a little option in the color picker which would show the "linear" (perceptually) color wheel and spectrum so that you could pick a color from that one instead – or when entering a color value it would allow you to "de-gamma" it right there?

I just lodged one. The more the better

http://www.autodesk.com/maya-sug