Telescope Reviews: How to get rid of noise

One thing I've recently "discovered" (but which may already be known to others, I'm not sure) is that in Registax, the settings of the higher wavelet layers influence the following layers. If you increase the wavelet parameter, but leave it set to 1.0, then move the slider on the lower wavelet slider, you reduce the amount of noise while practically not influencing the amount of detail (both detail reduction and noise reduction are quite subtle, but the detail reduction is clearly less than the noise reduction, so it's a net improvement.)

Find in attachment an example. This shows two Registax Layer settings (nothing else was touched, this is a 256/5000 frame stack of Copernicus at F/24 in the C9.25)

The red/green image is generated by clicking on the slider-value in registax and holding the mouse button. It shows the subtle noise reduction when the first layer is at 0.13 rather than 0.10 (notice that the first slider value remains 1.0, while the second slider is 50.0 in both images).

The second image is the picture as it is in Registax, the noise reduction is visible, but not extreme.

The third image is an unsharp mask of the image in Photoshop (Amount 200%, Radius 2.0, Threshold 0) which shows the very obvious improvement this provides in image quality when doing post processing, while I'm pretty sure the detail loss is absolutely minimal.

The unwaveletted stack is shown at the bottom (although obviously, this is an 8-bit jpeg, while the original stack has about 16-bits worth of grayscale).

I'm now using this method for 90% of my lunar images, usually in a slightly reduced form (I typically use a value of 0.11 (1.0) for my first lst layer and 0.10 (50.0) for my second layer, with the "Initial Layer" parameter at 2. This is giving me excellent results, combining this with Tony Gondola's High Pass Filter Processing technique and very slight noise reduction - default Photoshop Noise reduction, strength at 1 or 2 (rarely higher) and Preserve Details and Sharpen Details both at 10%.

It's only on occasions where the seeing wasn't all that great and I need a little more Oomph that I play further with the Registax parameters, to pull more detail out of the image. But this usually signals that I've lost my battle with the seeing, and it never delivers results anywhere near my better results.

The same trick can be applied to planets, but there usually I need to use other wavelet settings (but similar in concept)

Bart