Digital Light & Color

The only way I know to reduce chroma noise is with AS option. Is there any other way?

You might experiment with Bilateral Sharpen. For the illustration below, 10% gaussin RGB noise was added to the Bilateral transform Input image. The transform settings are: Amount = 100; Blur = 20; Blur Threshold = 10; Sharpen Factor = 45; and Sharpen Threshold = 0... NOTE: noise is not normally added when I use the transform for portrait skin smoothing.

You could try this:

1) Blur the original image A to produce blurred image B.
2) Split A and B into their respective HSV or HSL channels
3) Combine the V or L channel from A with the H and S channels from B.