Colors don't match between VFB interactive light mix and CoronaLight direct colr

[SharpEars]

So, a typical workflow:

You render with light mix and tweak light color and intensity. Then you take the tweaked values from the VFB LightMix and transfer them to the lights themselves. The problem is that the color as displayed in the VFB LightMix (color select dialog) does not match the color shown in 3dsmax CoronaLight modify panel direct color entry (dialog), when the HSV color values are identical.

To reproduce: Set an HSV value for a light in 3dsmax (modify panel) that has its own light select element. Set the same HSV value in the VFB LightMix. One is brighter than the other - they don't match exactly and they should. I am not sure if gamma is in play here or what, but the same HSV values should produce the same colors between the VFB LightMix and the 3dsmax CoronaLight modify panel direct color settings.

[TomG]

I may be misunderstanding :) The colours in the LightMix act as multipliers to the original light colour (as do the intensities). This means that white, intensity 1, in the LightMix controls gives you "the same colour as the original light source".

If you set the light colour in the LightMix controls as well as on the light, then you are changing the colour of the light (now it's original colour * original colour). This is unless you mean "Set colour in the CoronaLight and leave LightMix white" vs "Set CoronaLight to white and set LightMix to the light colour" and those are giving different results?

[SharpEars]

I may be misunderstanding :) The colours in the LightMix act as multipliers to the original light colour (as do the intensities). This means that white, intensity 1, in the LightMix controls gives you "the same colour as the original light source".

If you set the light colour in the LightMix controls as well as on the light, then you are changing the colour of the light (now it's original colour * original colour). This is unless you mean "Set colour in the CoronaLight and leave LightMix white" vs "Set CoronaLight to white and set LightMix to the light colour" and those are giving different results?

I wasn't aware that the LightMix colors are multiplied by the original colors. But in any case, the color displayed in the dialog boxes for selecting a color should match (or this is my understanding) and they do not. For my tests, I always start with lights that emit pure white (255,255,255 RGB). I then tune the color in LightMix VFB using the color picker dialog box used to change the color (let's ignore intensity and assume it is left unchaged at 1.0 in the LightMix LightSelect). Then I try to transfer the tweaked color settings from the LightMix VFB LightSelect color picker to the actual light source using the 3ds max modify panel (direct light color entry color picker dialog box). Of course I would then reset the LightSelect color to white so as not to impact the light source further, but let's ignore this step for the moment.

So, when I do this and plug the HSV values from the LightMix VFB's dialog box that pops up when you click on a color rectangle for a particular LightSelect element, the resulting color in the dialog box that I am entering into (the one from the 3ds max direct light color entry dialog box) does not match even though the HSV values are the same. This should be fairly easy to reproduce:

Create a single CoronaLight light that is pure white and has intensity of 1.0 - the most trivial light source. Create a light mix and light select for this light (environment excluded). Do a render and tweak the color of the light in the VFB to some saturated color like say mid brightness lime green at the end of the render. Then try to modify the color of the actual light source (which is currently white) to match that of the LightSelect element for it in the VFB. Have both dialog boxes open (the VFB LightSelect color picker and the 3ds max modify light panel direct color picker) and match the HSV values between the 3ds max color picker to the VFB color picker. Do the resulting colors look different (in lightness and perhaps saturation) when compared by eye between the two dialog boxes?

[TomG]

I'm using the Corona Color Picker for each.

Result was that if I enter HSV values, there is a slight difference in the RGB values (the Blue in the RGB is 2 less) - but that appears to be because a range of RGB values give the same HSV results.

Steps
Create Corona Light with default white colour
Render
Adjust colour in the VFB for that light (using Corona Color Picker in sRGB mode)
Open the colour for the light (in another Corona Color Picker in sRGB mode)
Enter the HSV values in the Light to match the VFB LightSelect colour
Slight difference in RGB
Enter the RGB values in the Light to match the VFB LightSelect colour
RGB now matches. The HSV matches too and doesn't change with that alteration in the RGB values.

Two images attached, one showing the result from entering HSV, one from entering the RGB (the midpoint RGB blue value of 115 also gives the same HSV values)

[SharpEars]

I'm using the Corona Color Picker for each.

Result was that if I enter HSV values, there is a slight difference in the RGB values (the Blue in the RGB is 2 less) - but that appears to be because a range of RGB values give the same HSV results.

Steps
Create Corona Light with default white colour
Render
Adjust colour in the VFB for that light (using Corona Color Picker in sRGB mode)
Open the colour for the light (in another Corona Color Picker in sRGB mode)
Enter the HSV values in the Light to match the VFB LightSelect colour
Slight difference in RGB
Enter the RGB values in the Light to match the VFB LightSelect colour
RGB now matches. The HSV matches too and doesn't change with that alteration in the RGB values.

Two images attached, one showing the result from entering HSV, one from entering the RGB (the midpoint RGB blue value of 115 also gives the same HSV values)

The HSV/RGB mismatch is normal, they do not map directly (or there is a an error amount). I will see if I can reproduce and attach a screenshot...

[TomG]

TY! Let me know how it goes and can restest here with what you find!

[SharpEars]

TY! Let me know how it goes and can restest here with what you find!

Thanks and what were your 3dsmax Gamma and linear workflow settings, btw (2.2 default gamma and linear workflow turned off? Not sure if these affect the results, but I always have the default gamma of 2.2 and turned on per Autodesk recommendation. I don't remember if I had linear workflow on/off, will double check when trying to reproduce the issue).

[TomG]

Quick screengrab!