How can I repeat this odd behavior, like with a script?

gniiial

Hey there, I made some renders. (...like averyone else too I guess... )
I stumbled across some unwanted fireflies, that multiplied with every iteration or got even stronger. After arround 200 iterations I searched some topics about that. Nothing new there and I also had the settings already includet. But then I tweaked arround and as I was rendering the next test, after 11 or 12 iterations the blueish picture two was showing up. I did not realize it at first, but this image can be a huge timesaver in general for renders, since you can save many unnecessary iterations by combining this secod image with your original, firefly or grain infested original. 

The Result will be image 3 - in psd or gimp or the image editor of your choice with some features like layering. For Psd this image was created by using 5 layers at the end. 

Get the original and the blue one in, set the blueish one to luminosity.

Layers:
2. blue one -  luminosity
1. Org

Merge them to one layer,
use Mark/Mask all
cut

and go three steps back. Put this one above the blue one and set it to linear dodge. This will put some extra colorization into the picture again.

Layers:
3. New merged Layer of both -  linear dodge 100%
2. blue one -  luminosity
1. Org

Now dublicate this layer, set it to color with a fill opacity to 33 % and dublicate this layer three times (at least for me this was enough to get close to my original look) This will step by step bring a more realistic colorization back into the picture. Done!

Layers:

3. New merged Layer of both -   color 33 %
3. New merged Layer of both -   color 33 %
3. New merged Layer of both -   color 33 %
3. New merged Layer of both -  linear dodge 100%
2. blue one -  luminosity
1. Org

It's clear that we cannot do much with this 12 Iterations layer and also cannot get our "colorization" back. But we have a cleaner image with everything we need. In DAZ3d I used the following render and filter settings (I include them as dl) and rendered 12 iterations only! The result is the blueish image, which has nearly no noise AND no firefly infestation. You could do the first render with less than arround 200 iterations. My first approch was arround 200 i think. It took a while... Anyways. Do both images 4000x2817 as I did or choose your original size*2. Watch the iterations become acceptable. This should be between 25-30... at least it's for me. Keep in mind that a reduction times 2 should clear most of the grain and the blueish image is basically "crisp" enough to push you over the edge of a quite nice result.


Now to my question. Isn't it possible to achive this with the render engine somehow? I mean for real, in general for this image I only needed 27 + 12 iterations. So basically with all layers I would come up to 120 iterations. I get not even this close by just rendering 200-250 frames. It's more likely that the fireflies stack up. The grain itself reduces way to slow with every iteration. It cannot be this hard to use this for faster rendering processes, without the "postwork" after it... Or am I wrong? I mean i basically did nothing than to layer images and gave them simplest features, with no extra efford... 

And to be clear, I could only render this little setup with Cpu. I guess there was to much to take in, since these are Gen9's with a lot of morphing, reworked clothing and plain and simple way to detailed textures and upgraded shading systems. Reducing texture image size by 4 made it possible to render this thing with gpu, but my GTX 1070 Ti still needet 3 minutes to get to 27 iterations and generates also fireflies. But hey, there are in other places now... 

Have a nice day...