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Messages - Jpjapers

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Hello, unfortunately, I was not able to reproduce this issue. May I please ask you to provide a little bit more details?
You can also submit a ticket to us using this link:

Hi, What was the result of your testing of the issue? What did you see happen?


edit: Ive just retested and youre right. I think it must be because when switching between units, it adjusts the intensity and perhaps lux to lumens was jumping to an intensity where the dimming would not be noticeable because it is so bright.
This thread can be deleted/solved.

I have little knowledge on light metering, but this is backed up with Wikipedia and a quick chat with our devs:

lux is illuminance (luminous flux incident on a surface)
you can, for example, spread a flux of 1000 lumens over some area
full moon has specific lux, overcast day, office area, etc

lumen is luminous flux
it is the total quantity of emitted light

Lumens are usually used to measure "light intensity" (how much light a light source emits).
Lux is usually used to measure the amount of light on some area.
Generally, lux as a unit makes little sense as a light source intensity unit.

From Wikipedia: "The difference between the units lumen and lux is that the lux takes into account the area over which the luminous flux is spread. A flux of 1,000 lumens, concentrated into an area of one square metre, lights up that square metre with an illuminance of 1,000 lux. The same 1,000 lumens, spread out over ten square metres, produces a dimmer illuminance of only 100 lux. Mathematically, 1 lx = 1 lm/m2."
^The above is also true for a Corona Light.

Let's imagine a rectangular surface which has some width and length. This surface reflects all the light it receives. We measure illuminance over that surface and we get a lux measure of X lux.
Now, if we create a rectangle Corona Light, set its width and length to the same values as that surface from previous example and set its intensity to the same number of X lux, then we can say that the this light has the same "brightness" as the surface from the previous example.

Thanks Maru, i actually did a post on what you described a few years back on someones tonemapping thread after doing a deep dive so i think i understand the difference in units and the relationship between them quite well at this point. My only real query was whether corona used the standard 1 lumen m2 = 1 lux at 1m unit as per this diagram or whether it was usingscene units but youve covered that so thank you!

Not a super-critical bug as i imagine not many people actually would notice but i see that in Corona 9 that when changing light units with IR running, the behaviour of the corona light doesnt change to match the new unit until you restart IR.

Hard to communicate what i mean by behaviour exactly but Obviously if i pick lumens as my unit, the Lux of the surface the light is covering reduces, the larger the light gets whereas W/sr.m^2 maintains the same lux level on surface regardless of light size. This is how it should be. However, until IR is restarted, the light does not change the way it outputs the light.

Im sure very few people would ever notice this unless you had a decent grasp of the light units and what they actually measure but thought id point it out.

Getting precise sub <50 RGB values is indeed hassle, it's funny that it is hardcoded so that it doesn't matter what kind of conversion is displayed on top by Corona.

Thankfully im seeing that in the current max beta,colour management is a thing. So hopefully in a few versions time we might see it in corona.

As far as I understand the root cause is that 3ds Max is not color managed, so we are converting between RGB with gamma 2.2 (or sRGB?) and linear. Linear has many "dark" values, but 2.2/sRGB doesn't. So if you pick a value close to the dark end of the gradient, then this cannot be converted and is instead crushed into pure black (or a slightly different value).

Image for visualization of the problem:

If you were to report this to Autodesk, then I think the feature request would be "Make 3ds Max color-managed".

That picture genuinely is the best way ive ever seen the differences in spaces illustrated and now it makes sense why this happens. Thanks Maru.

Apparently this is related to a known limitation coming from 3ds Max, which unfortunately Corona has no control over:

If i was to report this directly to the Max developers, any idea what i should cite as the potential issue and solution?

[Max] I need help! / Colour profile confusion
« on: 2023-03-10, 11:12:29 »
Ever since I bought iPhone I just realize daily how much better is everything solved there. Yes they have it easier but still.

Heh I have two of the best, most expensive Windows laptops in a world. And they can't even keep stable WiFi driver no matter what :- D And how on earth is WiFi driver capable of BSODin the whole system?

Given majority of my clients are US based, I can sleep soundly knowing that if I send them TIFF file with embedded sRGB or wide-gamut DCI-P3/AdobeRGB, I know they will see it correctly. Whereas in Windows, the main photo app (the main one!!) doesn't even support doing that properly.

The only way to have usable experience in Windows across full range of apps, is the NoVideo (just for nVidia) sRGB (it can do others too, incl. ICC) app from Github which superimposes color-profile onto everything, superseding Windows Color Management. This one: It works on laptop too, but you have to disable Optimus and only run dedicated nVidia card.

Windows can't even do HDR well, it can't do color-management well, list just goes forever. How little improvement has Windows11 brought to table is not even worth ranting over :- ).

And 3dsMax only having single gamma value that's also hilarious. I think it's the only DCC app without CC. While I am not such big fan of the VFX influence forcing ACES and .EXR and etc.. at least it will standardize CC across apps. All I wanted was just capability to display with ICC and save with color-profile from framebuffer, ideally in Adobe DNG format.

Ah man, feels good to shit on this topic :- )

Having never been a mac user, when i asked my colleague to show me the mac colour management dialog i was blown away at the depth of ICC profiles on the retina display. That NoVideo thing looks super useful. I did wonder why nVidia doesnt have a gpu-wide setting for this or even their own calibration device.

A few questions,

In terms of calibration, do you use a calibration device on your monitors? With that NoVideo thing, do you calibrate with or without it enabled? Do you calibrate with it disabled and then enable it?

If a colour falls outside of the sRGB range but it has an sRGB profile attached, will that colour still clamp on a display thats capable of showing the out-of-gamut colour?
Im working on windows but those doing the signoff are on iMacs and im wondering how to go about ensuring that colours translate correctly across devices.

Also, what profile should i be assigning to corona renders? Should i be opening them in Photoshop and assigning the sRGB profile?

All those long threads were effectively about 3dsMax not having any color management, so it will simply stretch towards whatever gamut the current monitor is showing.
Vray has ColorManaged both input (even for colors and textures but the ICC node has to be used) and output (it's in framebuffer).

Assign Profile should never be used, it's meant to be used when you know what color-space the input is, but the color-profile tag was lost, or the file format didn't support.

Photoshop defaults should be to ask what to do, but they can accidently become something else.

Rumour is new 3dsMax might have something to change here. 3dsMax and Corona are somewhat playing a game of cat and mouse who will do it first :- ). It's nightmare for people who need color-critical work, but also it's 2023 and people are adopting wide-gamut in masse thanks to HDR popularity. This will need to change soon.

I was hoping you might chime in as if i recall, you had a lot to say on the topic.
I basically didnt know how important embedded image profiles were for interchange and how much of a mess colour profiles are between programs but i have been enlightened and now i dont think ill ever not check exif data of anything during interchange or before sending an image to anyone. That was the root of my issue though. i was using photoshop defaults for colour settings and also assigning the sRGB profile rather than converting.

I did find an interesting plugin that offers some colour management but i believe it is only for Vray

Very interested to see how this topic evolves over the coming years with the adoption of wider gamut monitors. It would make sense that a newer standard than sRGB is adopted given it initially existed for CRT's. I imagine it would be such a mess for a number of years though and there would probably need to be MUCH better colour management in windows. I mean this whole thing has really made me consider buying a Mac for the better OS-Wide management and that has never been something ive considered before!

I dont think its a corona specific thing i just thought it was best to post here because there has been lots of threads about linear and srgb and colour space etc.

Ive figured out my process for getting colours through from calibrated images in lightroom after watching these videos and essentially immersing myself in the topic all day. So my issue was somewhat of a PEBKAC issue for not knowing much about the mess that is colour management but now ive got my head around embedded profiles things make more sense and ive managed to get my colours in bitmap and in RGB into max correctly (aside from the picker bug i reported today;topicseen). It looks like my photoshop defaults for colour management were the problem. Once i tagged my lightroom exports with Prophoto embedded, brought it into PS and converted to sRGB everything worked as intended.

These videos were very very informative on this topic and would recommend for anyone struggling to get their head around colour space. The pickers one was also just complete nightmare fuel!

Letting everybody interested know that this is currently possible to do, you just need to create the colors (or maybe there are already created libraries) and save it as a separate library.

Its also possible with the third party plugin i linked in my initial post.

Theres still weird stuff happening in V9.

1. If i enter values in the R,G,B Fields they change themselves once i leave the picker.

19,39,39 changes to 21,39,39
16,27,29 changes to 21,28,28

2. The colours shown in the node preview window are not accurate to the values that have been entered. If you picker the preview window with the corona picker, the displayed colours RGB values are out by one or two points. This is also proven by taking a screenshot of the colour and checking the RGB values in MS Paint.

3. Even when you do change the values, the preview doesnt always update to reflect them.

I can load in an image from photoshop with the values i want, picker the image preview with the corona picker and the picker will change the values.

Videos attached.

[Max] I need help! / Colour profile confusion
« on: 2023-03-08, 11:27:02 »
I Have photographed a load of swatches and used a Spyder Checkr to calibrate them in lightroom.
I then saved them as TIF files and open them in photoshop. At this point, photoshop has the ProPhoto profile assigned. Just changing it to sRGB changes the colours so i need to convert to sRGB rather than just Assign the sRGB profile.

So I convert to sRGB profile, the colours still look correct, and I picker the colour to get the hex code. When i put this hex code into a corona color map, it displays incorrectly. And i dont just mean brighter or darker, i mean that something green turns blue. But the hex code is the same.

How can i get the colour that i can see in Lightroom & PS & even illustrator, into max?

I know that theres been many long threads here about colour management and i could really use some advice. Ive been trying for days to figure this out.
I must be doing some process wrong as the colours i see on screen in Adobe products are correct to the real swatches i have. But outside of Adobe software i cant seem to get them to display correctly.



This would improve my everyday workflow sooo much.

Such a small thing but a real quality of life upgrade day to day. In the meantime, that third party one is really useful.

So ive jumped on to corona 9 as i ran out of ideas how to achieve what i needed to and it all seems to be fine with the linear sliders.

I like the idea. PANTONE system for example is built-in inside Revit. One can pick an exact color from it and then do the documentation.
Ofcourse colors in a 3D application can be very "subjective" as there are many things affecting and giving the final look of the color, then it can be color corrected, white-balanced et.c but it's better to have something than nothing.
I think it will be good to maybe have a poll, and see what actual color pallets designers/corona artists use, then these colors can be somehow integrated in CoronaColor map.
RAL catalogue will make the most sense I think, almost every other color can be referenced or converted from it.

RAL seems to be very much a european thing. Ive been working remotely from the UK for a US company for the last 18 months and we have been doing lots of design viz using renders to make decisions before time and im used to using RAL and Pantone but they just didnt use RAL at all and it seems like its not used much over there. I could be completely wrong and if some americans want to chime in that would be useful.

Having built-in colours that it ships with would be great but definitely the ability to load your own through CSV or even to save a colour to an existing library file from within the node would be fantastic for those who need specific libraries such as for packaging renders where the manufacturer has specific brand colours.

I would suggest;

  • Pantone/Freetone
  • RAL
  • BS
  • NCS
  • PPG/Johnstones
  • Dulux
  • AMS
  • Sherwin-Williams
  • Farrow & Ball
  • Munsell

But as i say even if most of those ended up being community contributions, the feature alone would be useful.

Youre right in saying that theres a lot of stuff that affects the perceived colour. Ive sat all day today photographing manufacturer-supplied physical colour samples in a lightbox with a Macbeth chart to colour correct them, just because i didn't think their web samples were at all accurate and i was very very right.

It would also be useful to be able to enter LAB values.

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