Avoid grainy in Lux renders

Tab "Noise Reduction".

Select "Regularization". Reduce "Amplitude" to 50 and check "Enable".
Select "Adv". For "Interpolation type" select "Runge-Kutta".

At the bottom click "Apply".

Watch the status line. It will show "Activity: Tonemapping" for a while. If you play with "Amplitude" or other parameters be aware that you may not see the result immediately. This is because the tonemapping process need time to compute. So click "Apply" if activity is an empty field.

You can anytime click "Reset" to get back what you started with.

Try the "Color Space" tab. Here you can change the base-color your render is using (night, daylight, etc). 

Note that nothing you do in the left tabs interrupts the render process.

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