@s7habo hey Boris you know I haven’t been able to replicate your results! First of all the white balance (but I don’t think it’s the key aspect here) – I used spot metering and draw a rectangle on the white area around the window, did you perhaps included the whole window with also a bit of frame (the wall around the window) like the screenshot you posted?
[this is my white balance settings plus spot area]
Also, did you increase a bit the exposure before applying the first curve? (I did, about +1ev).
Then step 3, when you say “repeated the process with the curve”, you mean you added a second tone curve instance, with same shape drawn on the b channel this time applying the mask? This is what I did but it only decreases the overall saturation quite a bit – plus my mask does not look at all like yours.
[this is my first curve applied, no masking]
[this is the second curve, tryng to replicate point n3 of your list as I understand it, with resulting mask which is very sensitive about the input values to the left – increasing them just a tiny bit makes the entire mask go away because as you see the values are all below 0]
And Velvia? I bumped it up to 75% but I get no punchy natural colors like yours, my image is still flat!
Sorry but your version is the one I liked the most and my inability to replicate it is a bit disappointing!