Smooth Gradient Transformation - Jitter

[frip51]

Hey there,
in the VfSU section there was a question about smooth gradients (over here).
As a matter of fact, 8-bit file formats can only store a limited colour range. But it makes a little big difference whether these colours are joined to form large areas (and show gradient steps) or whether there's some sort of jitter effect to break up the colour area borders for a smooth appearance.

I wish for a gradient jitter checkbox when saving 8-bit formats.


I'm just posting this regardless of any possible settings I didn't discover, yet.
So, if there's a way to avoid this by tweaking the options please fill me in and delete this thread from the wishlist.


Cheers,
Matt

[Micha_cg]

Re: Smooth Gradient Transformation - Jitter

I think, gradient levels at walls are caused by the TFT screen often. Calibration or an old CRT could solve the problem. You could test: is the color value jump between two visible levels only one greystep, than nothing can be done with the image, the display is the problem.

[frip51]

Re: Smooth Gradient Transformation - Jitter

Micha,
I have to disagree. At least partly
It's not only about what display you're using. But it's also a matter of how the image is being treated on saving the information.
If you have a look at the procedure I posted in the linked thread (see original post), you'll get a completely different result. And this is what I'm asking for

Look at this:



I don't know what exactly Photoshop does when the image is being converted to 8-bit. But it must be something else than the save command in V-Ray...


Cheers,
Matt

[Micha_cg]

Re: Smooth Gradient Transformation - Jitter

I see no levels anywhere. Maybe an example without texture could better show the leveling.

[frip51]

Re: Smooth Gradient Transformation - Jitter

Micha,
I'm referring to the blue thing in the centre - it's not textured, it's slightly backlit.
On these here monitors (Eizo FlexScan EV 2333W @3840x1080, 32-bit, HUEYpro calibrated), I do see a massive difference.

Also, in printing it's not the same (you might encounter that when using the vignetting option of the physical camera on plain white background). Dunno how to prove that right now...

Here's one bigger example:



Driving up the highlights in Photoshop may give you a better indication of what I'm aiming at:




Does that make sense?


Cheers,
Matt

[Micha_cg]

Re: Smooth Gradient Transformation - Jitter

Hmm, I see it now. I think, here should Vlado or the Vray core team fix the problem. I'm not sure ASGvis is the right address for the problem, but they could report the problem to the chaosgroup.