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Simple list for 5 types of textures

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Re: Simple list for 5 types of textures

Unread postby RayCaster » Mon Jun 01, 2020 2:54 pm

If an image is correctly assigned(either manually or detected) as srgb why does it need a conversion aswell? Do the images that are grey scale need the Linear to srgb node?
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Re: Simple list for 5 types of textures

Unread postby dboude » Mon Jun 01, 2020 3:01 pm

Because internally everything is evaluated in linear. That's why it needs to be converted.

For greyscale it depends. If it controls a color channel (if you want a black and white render for example) the textures have to be in sRGB. If it controls another attribute (roughness, displacement, transmission etc ...) it has to be linear.

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Re: Simple list for 5 types of textures

Unread postby RayCaster » Mon Jun 01, 2020 4:21 pm

I get the BW image thing, if you want it in the colour slot, but are you saying that srgb rough or gloss need the srgb - linear node, as well as the diffuse slot, also 8 bit height maps?
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Re: Simple list for 5 types of textures

Unread postby dboude » Mon Jun 01, 2020 8:26 pm

I don't understand what you are saying... You want to use a BW image in color and in roughness for example ?

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Re: Simple list for 5 types of textures

Unread postby RayCaster » Mon Jun 01, 2020 11:16 pm

No i was picking up on what you said "For greyscale it depends. If it controls a color channel (if you want a black and white render for example) " Which I took to mean, its possible to add a BW image to the diffuse chan, if you want that texture to render as BW(Sin City :).
But to clarify what I was asking, most maps(mine anyway) are in the srgb space(no linear jpg's but maybe png's), so a rough,gloss,AO, spec or metal map is black & white & probably srgb, but I thought it was enough to flag it as raw data & force luminance, though perhaps needs to be left as srgb and add the colour space node? Though in most of the video's on line you dont see the colour space node getting used that much and if it is it's usually just in the diffuse slot. Almost sure that if I open a normal map in gimp i'd be seeing that in srgb? it would be 8bit so I assumed srgb also or is it saved with no colour profile assigned?
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Re: Simple list for 5 types of textures

Unread postby dboude » Tue Jun 02, 2020 9:54 am

Adding a color space to linearise your sRGB file is the same as checking "Raw Data" ;)
And yes if you open a normal map in gimp, gimp will apply an sRGB lut for the display.

Just keep in mind that all technical maps should be linear (= raw data) and all color map sRGB (or ACES or the LUT you want...)

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Re: Simple list for 5 types of textures

Unread postby RayCaster » Wed Jun 10, 2020 5:04 am

Yes thats how I thought it worked, but i'm still left confused(but LWF has always had that effect on me)
One minute I think I understand but the doubts still there, and every time I try to write about it I realize i'm into writing a long essay on screen display gamma, film response, textures & lighting etc...I know the words but have not absorbed the math/science :( not got into aces yet.
In the past for me LWF was more about faster lighter renders, and maybe a little more realism.
srgb-lin.jpg

But I need to confirm, if you have an image correctly auto identified as srgb do you still need a node srgb-linear.
or in Aces Utility srgb texture - acescg

if you have AO use raw data( though if you used auto it may choose srgb) & diffuse as srgb (with srg - linear node) do you multiply the AO before or after the srgb-linear(assume after), also if you have a gloss map but no rough, do you put the gloss in the rough slots and invert it, or does it go elsewhere?

I know this is a dumb fundamental I should know, but need a definitive conformation to post a sticky note in my failing grey matter, LWF always done my head in, always wondered why shooting flat in slog was better for grading, but in linear 96bit images they only look flat when everything is wrong :( Dont think i'll be getting a job as a colour grader anytime soon, it would be really interesting to see more video's on how people are using ACES in a workflow, obviously handy for integrating footage into clarisse.

It seems counter intuitive to render out srgb images and throw all the linear info away, but as I understand it, it's supposed to be quicker, or rendering to a specifc Look Lut(rather than applying a LUT in post), is like adding a look filter to a camera, instead of filming without and adding later. But i'm now wondering if you are rendering to srgb and you have linear IBL, and a copy of that IBL map file on a sphere with matte texture, do you have to add a colour space conversion to the BG sphere image? and maybe turn it off if you render in linear or acescg.

Hopefully you understand my ramblings more than me :)
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Re: Simple list for 5 types of textures

Unread postby dboude » Wed Jun 10, 2020 1:03 pm

The color space node is useful if your map file is set to linear or raw. If you convert the texture in the map file you won't need the color space node. It's up to you how you want to organize your project.

For the AO texture, it's like any other texture. If you use it in a color channel then you have to convert it (sRGB, ACES etc...) but if it's to drive some attribute let it in linear.

And yes, the glossy is the inverse of the roughness.

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Re: Simple list for 5 types of textures

Unread postby RayCaster » Wed Jun 10, 2020 1:33 pm

ok thats simple but still confusing, sorry for being so dumb, lets try your first paragraph

The Diffuse map isnt Linear or Raw so adding the node srgb-linear must produce the wrong result, or adding utility texture srgb - acescg would also be wrong?

the AO is probably 8bit but I thought you check Raw Data for that, and then multiplied with diffuse, but reading your comment makes me think dont check raw and multiply with diffuse and then add the node srgb-linear(but you say the node is only used if linear or Raw is checked)
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Re: Simple list for 5 types of textures

Unread postby dboude » Wed Jun 10, 2020 2:32 pm

You have to see (with your eyes) the diffuse maps in sRGB but the texture is written as raw data on the disk (except if you encoded specifically the LUT in it). So for most of the color textures you can find you have to convert them in sRGB otherwise the colors would be wrong to your eyes. Same way for AO, but AO can be used as a technical map as well. If you use it in color channel, convert it to sRGB otherwise not. 8bit, 16bit 32bit it doesn't matter.

You can change the color space of textures in the map file itself OR with the color space node. So if you let a color texture in raw in the map file you will need the color space node. If you set sRGB in the map file itself you won't need the color space node. That's why I was saying "It's up to you, up to your workflow"

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