Author Topic: Tonemapping - Plz Halp  (Read 115754 times)

2020-05-11, 17:11:24
Reply #330

maru

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Great to see that fstorm still does heavy GI clamping. It was the same last time we checked. ;)
I wonder how fast it would be with GI clamping on Corona level.
Marcin Miodek | chaos-corona.com
3D Support Team Lead - Corona | contact us

2020-05-11, 20:06:54
Reply #331

lupaz

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So, dudes & devs:

thanks to a hint from our buddy CJWIDD, I switched to Dubcat´s ACES simulation HC 0.7, etc.
After tens of renders (interiors) in the last days, this will stay standard setting for me... despite the stronger burning in the highlights.

Renders (contrasts, gradients, etc.) look waaaay more photo-like and more natural to the eye with HC 0.7. Especially in small rooms with poor light sources, you get much more energy.
Details that looked totally washed out at HC 1 and above, suddenly appear and the lighting becomes natural and alive.

In my humble opinion, the base setting of the HC in Corona seems too high. That's why images always look rather washed out & grayish and one messes around with contrasts to compensate it - with the known side effects of color burning, etc.

HC lower than 1 as a standard and a better / stronger effect of filmic highlights, so one can reduce clipping to a natural degree when needed, would be perfect in Corona.

What do you guys think?

In my opinion you loose contrast with this setup.
But at this point it's a matter of preference or taste I think. Same as with LUTs.

2020-05-11, 20:47:03
Reply #332

hldemi

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A sub-topic that - in my opinion - is very important in this context, is the highlight compression. This would deserve a special attention from the devs.

From electronic music recording, some of you might know compression and... really great compression like for example that from UAD.
"Normal" audio compressors brutally cut away frequencies, leaving behind a dull and deaf sound without details.
A similar effect I see in digital picture compression.

Question: is it technically possible to program a HC that compresses while still leaving much details?
Or the same behavior for the Filmic Highlight - especially handy when using HC lower than 1.

At the moment, either you crank up the HC and land in a dull image, or you lower HC, get way nicer lighting but the Filmic Highlight has to be pushed up to brutal values as compensation,
so your highlight lose most details.

I figured that filmic highlights on 1 reduces all of the light dynamics but real magic happens at values infinitely close to 1 haha. around 0.95-0.99 is sweet spot.

2020-05-11, 22:07:18
Reply #333

Designerman77

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0.7 has been my starting point for a long time though i sometimes take it up to Max 2.5 in some circumstances.
[/quote]


Since I realized how dull and grey images get, as soon as you touch the HC... even a bit over 1.0, I keep my fingers away from it and only use filmic highlight, wich only affects
the very bright area. I observed that cranking up filmic highlights even increases light dynamic in other areas, such as on white walls.

From my early days with rendering, when I worked with Max (meanwhile with C4D), I remember that the on-board highlight compression in Max / MentalRay only affected the burnt lights,
without diminishing the overall dynamics. That was 2009 ! and you could get some pretty nice images.

That's what I would actually also expect from the Corona HC. Compress the clipping but don't dip the rest of the image into grey light.

2020-05-11, 22:09:33
Reply #334

Designerman77

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I figured that filmic highlights on 1 reduces all of the light dynamics but real magic happens at values infinitely close to 1 haha. around 0.95-0.99 is sweet spot.
[/quote]


Yes, I confirm your observation! :)

In extreme light situations, when lower filmic highlight values don't do the job, 8.5 - 9.9 can do miracles. :)))))
But if it eats up too many details in other areas, I leave it a bit burnt and clamp it in PS.

2020-05-11, 22:15:08
Reply #335

Designerman77

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I've been using <1.0 HC, as is described in Dubcat's ACES emulation settings, and it *feels* like it brings back dynamic range, i.e. the image looks more punchy, more depth
[/quote]

I never tried those settings. I have to admit they sound completely nonsense for me, on paper at least. Maybe the combination with filmic highlight counterbalances the 0.7 HC compression. I'll give it a go tho, as Dubcat always conducted is tests rigorously and always delivered good stuff. Settings are attached for those wondering.
[/quote]

This is without any LUT?
[/quote]


No, with Kim Amland 02.
Sorry, I forgot to mention it.


2020-05-13, 16:28:28
Reply #336

hldemi

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Designman77, gave myself a go at empty apartment rendering. Also HC 0.7 but went with soft blacks in curves to get filmic feel.
I feel that contrast need to be lowered far under 1 if we go with very low HC values.

2020-05-14, 04:20:29
Reply #337

cjwidd

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@hldemi can you post a screenshot of the tonemapping settings for this shot, including any LUTs or curves that were used, and what was the light source(s)?

2020-05-14, 16:31:52
Reply #338

hldemi

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@hldemi can you post a screenshot of the tonemapping settings for this shot, including any LUTs or curves that were used, and what was the light source(s)?

Sure. Its in attachment, I just did 20 passes in this SS. Original render took around 5 minutes.

As a LUT I used barnet from DELUTS 4 collection. It just give a bit of contrast and warmth. As you can see curve is just to for black. Always a bit up, I hate crushing blacks.
Light is extremely simple, only 2 light sources, corona sun and corona sky. Corona 5 not C6 daily.

2020-05-14, 17:21:58
Reply #339

Designerman77

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@hldemi can you post a screenshot of the tonemapping settings for this shot, including any LUTs or curves that were used, and what was the light source(s)?

Sure. Its in attachment, I just did 20 passes in this SS. Original render took around 5 minutes.

As a LUT I used barnet from DELUTS 4 collection. It just give a bit of contrast and warmth. As you can see curve is just to for black. Always a bit up, I hate crushing blacks.
Light is extremely simple, only 2 light sources, corona sun and corona sky. Corona 5 not C6 daily.



Funny, I had a look at this thread exactly for this topic, and now you posted an example of your own. Very cool!

Exactly, pushing the blacks up in the curve became also my standard lately. Plus reducing the reds in the shadows makes images more realistic.
Also less reds in the mids & highlights has a positive effect on realism.

As mentioned before, I feel that the renders that look most fake, are those with too much red tone in the overall lighting... which... :)))) seems to appear quite often in Corona´s basic light behavior.
Remember? Someone here said "FStorm" looks always so greenish, etc. Yep... that greenish tint is somehow easier accepted by our eyes.


P.S. I try to not touch filmic shadows because it washes out your dynamics (similar to HC 1+), gradients on walls, contrasts etc.
That extra light it gives is not worth it. I rather get it by a bit higher exposure.
« Last Edit: 2020-05-14, 17:28:39 by Designerman77 »

2020-05-14, 17:32:01
Reply #340

hldemi

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Thats because red is not usually dominant color in nature. Blue is sky and seas. Green is well rest of earth for most time we as humans evolved. So normally our eyes perceive those colors as more natural. This however is just a rule to get to photo-realistic image easier.  Its does not mean that reddish images cannot be extremely photorealistic .

To me, it does not matter much. One should strive to improve himself, render engines are fine :D

2020-05-14, 17:55:37
Reply #341

Designerman77

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Thats because red is not usually dominant color in nature. Blue is sky and seas. Green is well rest of earth for most time we as humans evolved. So normally our eyes perceive those colors as more natural. This however is just a rule to get to photo-realistic image easier.  Its does not mean that reddish images cannot be extremely photorealistic .

To me, it does not matter much. One should strive to improve himself, render engines are fine :D

Totally agree with you. A to of 3D realism is about creating lighting, colors & contrasts we are used to in real life.
However, as you mentioned, reddish light is instinctively perceived as more "artificial" and "unnatural"... probably because from those hours of daylight,
only a short period is dominated by red light.
Also, if you look at small rooms with weak, reddish lamps in reality... it is really unpleasant to the eyes... and it looks exactly like what it is: artificial... no matter if in a render or in reality. :)


Regarding "render engines are just fine" and it is up to us to create realistic images, I only agree 50%.
If the render engine simply does not simulate stuff, you can be Leonardo DaVinci and your images will never look real.

Just remember render engines 10 years ago... :))))


However, Corona is without doubt one of the best render engines on the market. I think among the top three.
And it is developing quite nicely.

2020-05-14, 18:40:52
Reply #342

hldemi

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Yeah but I am talking about industry standard physical ray tracers of modern day. All those engines are capable of creating images that would fool even most experienced eyes. If just for a second.

Regarding red lights. Yeah but orange is totally different story. Even at lowest point of sunset, light is still orange-ish. Also artificial can be equally photorealistic . Any light thats saturated more than lower 20% of the pallet looks artificial. This is why low contrast, desaturated images looks more natural. And again both can be photorealistic.

2020-05-14, 18:57:41
Reply #343

Designerman77

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Yeah but I am talking about industry standard physical ray tracers of modern day. All those engines are capable of creating images that would fool even most experienced eyes. If just for a second.

Regarding red lights. Yeah but orange is totally different story. Even at lowest point of sunset, light is still orange-ish. Also artificial can be equally photorealistic . Any light thats saturated more than lower 20% of the pallet looks artificial. This is why low contrast, desaturated images looks more natural. And again both can be photorealistic.

Interesting, did not know about that 20% saturation "rule of thumb".
Of course, any light or color mood can look photo-realistic. Only that - as you also mentioned - certain color moods look more "real" or believable to most of us, in the sense that a photo taken on Mars looks less natural than one taken in Monument valley.


2020-05-14, 19:06:52
Reply #344

hldemi

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Thats totally true. However I think that we as viz artists should not focus on natural look per se. In my images I always strive for the mood. If I want to to get the mood of Tokyo bordel in 2254 I would go for the oversaturated artificial lighting. But in a context of arch viz, you are absolutely right, looks that mostly please clients  are well lit, natural, airy and welcoming looks. Thats why if you are viz artist, arch viz will be mostly limiting. This is partly the reason Alex Roman got away from archviz for a while.