### Author Topic: What is the meaning of the - C8, C16, L8, L16 after the node resolution?  (Read 5554 times)

#### Jasper Drop 0

Hi,

I'm working myself through the tutorials and at the 'getting started 03 part 4' (blending base materials) I noticed that my 'Metal_Floor' node has -C8 as an extension after its resolution, while my rust has -C16. Somehow this propagates into the Base Color and Normal of my blended material, they both have -C8.

In the graph for my Metal_Floor i can see that the Base Color has -C8, the normal -C16 and the Metallic has -L8, I assume that these values make it that my Metal_Floor node has C8.(?) In my Rust only my Normal has a -L8

I tried to find a reference in the documentation, but i can't seem to find anything. I'm assuming it has to do with bits (8 or 16) and that the C = color and the L = linear. (?)

My questions:

- are my assumptions correct, and if not where are they wrong?
- is it a problem that one of my base material nodes has a -C8 ?
- is there a way (like with resolution) to force a -C8 into a C16?

Best regards,

Jasper

#### Celine Dameron

Hi Jasper,

C stands for Color and L for Luminance (or grayscale if you prefer).
And the number is the bit depth of your node.
For example :
- C8 means Color 8 bits
- L16 means Luminance/Grayscale 16 bits

I recommend you to work in 16 bits.
For example, if your basecolor is in 8 bits, you will have less colors available than in 16 bits.
The most visible and common problem regarding bit depth is with the normal map. Here is what happen when you have a normal map set in 8 bit.

Yes, you can modify the bit depth of your node just like the resolution. This parameter is called output format
Do to this, double click on your node to display its attributes.
Set the output format parameter to absolute, this way you will access to all the values available.
I made a gif to show how to solve bit depth issues. In this case my basecolor was in 8 bits instead of 16 bits so I forced a blend node to switch to 16 bits.

Hope this was clear enough
Last Edit: December 29, 2017, 03:47:07 pm
QA Analyst

#### Jasper Drop 0

But based on what i am seeing now, i still don't understand what is happening and why.

I checked my root graph and saw that the output format there was set relative to parent.
Apparently this is 8 bits by default. (??)

When i drag a  'Uniform Color'-node (default output Format is set to Relative to Parent) into my root graph it shows a -C8 extension.
But when i drag in a pattern (also default output Format is set to Relative to Parent) it shows a -C16 extension.

Why is this? If the pattern also got a -C8 I would have understood

Another Example below:

Why is the material blend in the picture C8 while all its inputs are 16 and it is set to 'Relative to Input'?
Why is it outputting a base color and normal with C8?
Should you always manualluy correct this, or is there another way to prevent this?

This can get really annoying, i spend hours yesterday in the 'aged wood planks' tutorial (creating the planks pattern) figuring out why my 'edge detect' kept showing vertical lines inside the tiles. This kept messing up the mask creation for the nail-positions whenever i changed the number of planks.

I finally figured out that this was because the tile generator had an -C8. DESPITE the fact that it was set to 'relative to input' and all its input (the gradient) was a -L16. So i set the output format of my root-graph to absolute 16 bits per channel and, finally got rid of those extra vertical lines and can happily continue with the tutorial.

Am i supposed to always set the Output Format in my root graph to an abolsute 16?
So why have an '8 bits per channel' option when it clearly causes problems errors?

Note: the wood plank tutorial was published on 20-12-2017 (so very recent) but the tile generator node in my 17.2.2 version was very different, making it hard to follow the tutorial.

Best regards,

Jasper
Last Edit: January 01, 2018, 11:09:03 am

#### sprqst

Was searching for similar info. So sad that there's no response to this (specially given that this is in the Tech Support section). Could've helped so much and seemed right on topic. I'll keep searching ...