Suggestions

Taron, that looks just lovely. Thank you!
Hahaha - well, maybe you haven't noticed, but I already used brush #2 to make pore like dots.
I am too digital and lazy, not to use this helpers
And if its well done, no one will see if it's manually done or with a little help of our digital friends.

[Taron]

Hahahaha, man...I used the brush image to suggest you make a NICE PORE TEXTURE, not just my ugly (falling asleep) dots!
Besides, depending on what you want to achieve, you'll have to play around with the possibilities including paint mode and image mode and so on...

Haha, sorry that I didn't answered. Yes, sure finally it will be a nice pore texture of course.
Meanwhile I had a thought about a probably quick transformation and distortion possibillity. Once pressed i you can activate an option to see the image brush as a 1 to 1 projection on canvas too.
Then you can execute the image brush directly to canvas, or use it as a brush for rotation and scale. The projection would make it a bit easier instead to see the image brush preview.
Some descent functions for the image brush selection frame, like 1to1 scale, proportional scale, flip and rotate and lot of missing stuff would be suddenly there.
Just a thought.

Is it possible to 'bake' the desaturation, not only temporary?

[Taron]

I would almost say: Hold your breath!

@Taron
Do you plan to offer to us users some form or scripting (like Lua, Python etc).
So we could for example write our own canvas texture or lighting setups or many other neat things?
After all, many of us are programmers here.
If nothing, just put it at your feature list (if it's not already there) and code with that in mind.
Thanks.

@zen
You can define the canvas with any picture, did you know that?
It is not as easy as I thought, or maybe I chose the hard way , but I managed to get this working:

EDIT: To explain following steps - the target is to get a png with some transparent alpha from your reference canvas picture to paint the height that is needed to convert it into a canvas.
Original example (Crop from original 4000x2700):

Dirty_Canvas_original.jpg (134.38 KiB) Viewed 10348 times

-Open the canvas pic in PS (there are plenty canvas pics on the net)
-Exaggerate contrast best with levels untill you have almost B&W
-Klick on channel
-STRG+click on i.e. red
-Now you should have a selection.
-click on RGB again.
-Go back to layers.
-Copy selection and paste it to new layer - now you should have some transparency.
-Save layer as png.

PS ready:

Dirty_Canvas_PS.jpg (124.33 KiB) Viewed 10348 times

-Go to verve and load png.
- make an image brush with "i"
-make a new layer
-Make brush 10 same size as canvas. switch off "w" "e"
-Paint with image brush.
-press CTRL+SHIFT+P to get actual layer as canvas.
Done

Dirty_Canvas_verve.jpg (113.8 KiB) Viewed 10348 times

You see, it is not one to one. It depends quite a bit how you tweak the pic in PS.

Turning a self painted picture/canvas structure into a verve canvas is a no brainer.
Paint the structure and press CTRL+SHIFT+p.
Watch out! STRG+p toggles between actual canvas, old canvas and your canvas. So you can hide you made canvas by mistake and think it haven't worked...like me

Maybe there is an easier possibility to use existing pics (taron?) , but that way described was the only way working for me.
Anyway you have a hell of varieties already available

[Taron]

OMG, Knacki, hahahahaha! Shiiiit, hehehe, I never even thought of that!
Brilliant!
Anyway, I have already successfully tried recording and playback of every possible action in Verve, which is kinda sweet! Since the playback works just fine, it shouldn't be a far cry to turn that into a little scripting solution, sure.
But I may just ponder over a pro version for that stuff, depending on how well the CONTRIBUTE solution will go. I do have faith in people, so chances are that it will fuel me to fulfill my desire to keep it free, but there are certain amounts of work that would be insane, if I would starve myself over them, you know. So...we shall see!

Thanks Knacki, I will try that!
btw. I would like to have more like procedural (with texture) canvas as Taron did for new canvas (something like on this painting).

@Taron
Can you pls find soulution for the "Moiré pattern" side effect of new canvas texture (cotton-like one). It happens mostly horizontally.
Or it's just side-effect how you tile the texture? (Can be seen here).
It's hard to see it without painting a canvas.

[Taron]

Hahaha, sorry, don't mean to laugh, but that's not a "tiled" texture. But both "density" and "bias" adjust the irregularities across the canvas and mild ones as well as certain stretch settings can bring out such an interference. I'd recommend playing with those parameters a little to see what happens!
Also, it ain't the last procedural, nor will I just leave it like that, if there's a way to improve it. And I know there is. Piece by piece, zen! Thanks for bringing it up, though!

Depending on the size of your canvas, or rather how big you want the texture to be, try size 41%, density 7%, bias 33%. That's something I just tried and it dissolves possible moire effects really well.