Hello boys and girls…
Sorry for inexperienced question, but…
Here I have some pics.
1. Input image, taked from Star Wars site just as a reference.

2. All possible colors are excluded by Primatte. Here I have some noise, which are NOT excluded, however hard I’ve tried…

3. …but alpha-channel is clear, because of “Mask shrink” option…

4. Ande the result are also bad 🙁 Here I still have that noise. Where I am wrong? You see, the result alpha-channel is right (see pic.3 )…

Thanks for help…