Problem

You have the felling that Strength parameter configured in GraXpert dialog box have no effect on final result. Moreover, when you activate GraXpert logs you see that parameter is always 1.0.

Solution

If you apply new Automatic Screen Transfer Functions after image denoising, residual noise will pop-up again. This doesn't mean denoising have no effect, it just means ne parameters in Screen Transfer Functions makes noise more visible.

The second thing is that Strength is processed in PixInsight using same rule as GraXpert Application:

Processed = Denoised * Strength + Original * (1 - Strength)

Where

• Processed is the result image displayed in PixInsight
• Denoise is the result of GraXpert AI with a Strenght 1.0
• Original is initial image

The main avantage is that we don't need to reprocess the image in GraXpert when you just change the Strength parameter. This is particular usefull when you do a Realtime preview or want to fine tune strength.

You can make a comparison with PixelMath and Statistics, at the end, result image is exactly the same:

Good to know

To compare two images you should always use same Screen Transfert Functions. To do so, apply an Automatic Screen Transfert Function on image used as reference and apply same value on the other image by drag & drop new STF instance (triangle on STF bottom left).

A strength 1.0 give AI response with a noise level similar to images provided during the model training. In some cases, you can boost the Strength over 1.0 to get a better result but this boost can introduce noise the AI is not responsible.