New script for denoising linear monochannel images

nm303

Active member
Feb 7, 2017
28
1
Got a chance to use MURE again with fresh data. It works phenomenally well. It's really like magic. Thanks and everybody stay safe during this strange Corona time.
 
  • Like
Reactions: pfile

mschuster

PTeam Member
Nov 27, 2011
1,137
6
San Francisco
New version MureDenoise 1.32 should appear soon as an auto update.

- Improved image normalization and weighting approximations, see the documentation for more information.

- Added to the process console log the standard deviation of method noise in DN, an estimate of the typical amount of noise guessed and removed from the image.

- Several other minor changes noted in the script's change log.
 
  • Like
Reactions: jmurphy and SdA

midnightlightning

Active member
Nov 26, 2018
41
3
@mschuster

Firstly, this script is awesome, Great job! I am getting great results but have two questions:

1) I have run the same data with Variances from 0.6 to 1.2 to test which gives the best result but am not sure how to compare the results having read #203 and #211 regarding DBE issues and how auto-STF treats noise. Should I compare images "as is" (original STF) after running Mure, or should I re-stretch with STF? If the latter should I use auto-stretch (24bit) or use the same black and mid-point values on each image? No doubt the answer is obvious but I have been going around in circles for the past couple of hours and depending what I do the results look different.

As an observation, with auto_STF and Variance 0.9 and above I see faint stars are progressively getting removed and the image gets grainier. With Variance 0.8 the faint stars are retained in line with the original. Variance 0.6 is full of artefacts. On this basis Variance 0.8 appears best, I know its subjective, but is this a reasonable way to select the optimal level of noise reduction?

2) Is it ok to use Mure after using NormaliseScaleGradient?

Thanks
 
Last edited:

jmurphy

PTeam Member
Jun 13, 2010
288
138
Basingstoke, England
2) Is it ok to use Mure after using NormaliseScaleGradient?
Now that NormaliseScaleGradient v1.3 reads the NOISExx headers that are added by WBPP, ImageCalibration or Debayer, it should be OK to use NoramliseScaleGradient after MureDenoise. The NOISExx noise estimates are important in this case because it is necessary to base the image weights on the noise present before noise removal (for example, the noise present before running MureDenoise).

It might be worth doing a test to see if MureDenoise conserves the star flux. Run with and without MureDenoise. Check to see if the NSG calculated scale factors are similar for both runs. You can find the scale in the console output, and it is also recorded in the FITS header. I expect this to be OK, but I have not yet tested it.

Regards, John Murphy
 
Last edited:
  • Like
Reactions: midnightlightning

midnightlightning

Active member
Nov 26, 2018
41
3
Now that NormaliseScaleGradient v1.3 reads the NOISExx headers that are added by WBPP, ImageCalibration or Debayer, it should be OK to use NoramliseScaleGradient after MureDenoise.

It might be worth doing a test to see if MureDenoise conserves the star flux. Run with and without MureDenoise. Check to see if the NSG calculated scale factors are similar for both runs. You can find the scale in the console output, and it is also recorded in the FITS header.

Regards, John Murphy
Maybe the answer is the same but I need to run Registration ==>NSG==>Integration==>Mure in that order?