StarTools

I have been applying the concepts of the two videos "Removing Vignetting and Complex Gradients" and "Lifting structures from heavy noise with Life" to a stack of 4 x 1.5 minute frames of the leo triplet at 430mm focal length from a 72mm refractor. I took darks and biases but no flats so there is a fair amount of vignetting and gradient. I have been able to successfully apply the wipe, but after using the life - isolate featue, there is a bright block around my galaxies. Actually it looks like the rest of the image is darkened except for a block around the galaxies. The galaxies are rather small and it looks like the life - isolate function has a minimum size that appears to be driven by the slider that I have currently set to 128x128. I can't make that number smaller, but if I make it bigger, the block around my galaxies increases. Your video shows the life - isolate feature being applied to a large nebula. In my case, they are small galaxies. Is there some minimum size to use this feature? How can I remove the bright blocks? I have tried contrast, wipe, and filter to no great success. Sorry I did not save my results, but I plan on redoing this exercise again and can post my results later.

I am using version 1.3.3.223 of StarTools on 32 bit Windows.

Thanks,

Jeff

Jeff2011 wrote:I have been applying the concepts of the two videos "Removing Vignetting and Complex Gradients" and "Lifting structures from heavy noise with Life" to a stack of 4 x 1.5 minute frames of the leo triplet at 430mm focal length from a 72mm refractor. I took darks and biases but no flats so there is a fair amount of vignetting and gradient. I have been able to successfully apply the wipe, but after using the life - isolate featue, there is a bright block around my galaxies. Actually it looks like the rest of the image is darkened except for a block around the galaxies. The galaxies are rather small and it looks like the life - isolate function has a minimum size that appears to be driven by the slider that I have currently set to 128x128. I can't make that number smaller, but if I make it bigger, the block around my galaxies increases. Your video shows the life - isolate feature being applied to a large nebula. In my case, they are small galaxies. Is there some minimum size to use this feature? How can I remove the bright blocks? I have tried contrast, wipe, and filter to no great success. Sorry I did not save my results, but I plan on redoing this exercise again and can post my results later.

Hi Jeff,


The Life module was designed for re-synthesising super structures (e.g. large areas). To speed up light diffraction calculation Life uses a windowed FIR (Finite Impulse Response) - you'll notice that if you increase this window, the results take much longer but look slightly better (the Airy Disk impulse tapers off as the distance from the center of the block increases). The blocks that you are seeing are the impulse response window boundaries. If there are only a few pixels that are (close to) white and are close together, then those impulse window boundaries will be 'smeared' over a small area and appear like blocks. However, if there are many pixels all over the place then all those boundaries will be scattered all over the place and will be next to invisible.

I have now updated StarTools (1.3.3.224) to taper off towards the FIR boundaries. Give the latest version a try and see how you go!

Cheers,

If there are only a few pixels that are (close to) white and are close together, then those impulse window boundaries will be 'smeared' over a small area and appear like blocks.

Ivo,

This makes sense, since the galaxy cores are bright and white. I will try your new update this evening. But in addition to your update, should I also mask off the bright core of the galaxies?

Thanks,

Jeff

Jeff2011 wrote:But in addition to your update, should I also mask off the bright core of the galaxies?

Not necessary Jeff (but some good lateral thinking there! ). The problem is a problem of detail size where small (abrupt) changes in brightness were getting 'echoed ' at the window boundaries. Masking out the brighter parts would help, but would also severely diminish the benefits of the Life module's Isolate preset. The boundaries now taper off, so hopefully it'll look better. If you have any trouble, do post your image (or a crop of it). There are other ways in StarTools to achieve a similar effect.

Ivo,

I ran with the 224 version and the blocks around the galaxies went away but the result were not as detailed and were more red. Attached is the comparison between the two after I ran the life module using each both versions. The final 224 image is after I applied the noise reduction after stopping tracking.

If you would like to work your magic on it, I can email you a link to my dropbox account with the source tiff from DSS.

Thanks,

Jeff

Jeff2011 wrote:Ivo,

I ran with the 224 version and the blocks around the galaxies went away but the result were not as detailed and were more red. Attached is the comparison between the two after I ran the life module using each both versions. The final 224 image is after I applied the noise reduction after stopping tracking.

If you would like to work your magic on it, I can email you a link to my dropbox account with the source tiff from DSS.

Thanks,

Jeff

Hi Jeff, happy to have a look at the Dropbox files!

Cheers,

Ivo,

Just sent you an email with link. You can post your result here if you like.

Thanks,

Jeff

Load file, indicate it is stil linear.
Auto Develop with default settings.
Severe gradient and light pollution.
Crop to frame the triplet a bit better; make sure the distance to the center of the crosshairs from each of the galaxies is equal.
Parameter [X1] set to [1422 pixels]
Parameter [Y1] set to [608 pixels]
Parameter [X2] set to [2266 pixels (-335)]
Parameter [Y2] set to [1239 pixels (-493)]
Wipe to get rid of gradient;
Default parameters, except for Parameter [Dark Anomaly Filter] set to [4 pixels]
Develop
Parameter [Digital Development] set to [98.22 %]
Parameter [Dark Anomaly Filter] set to [15.7 pixels]
Slight wavelet Sharpen to accentuate the galaxies (larger scales/objects).
Parameter [Scale 1] set to [4 %]
Parameter [Scale 2] set to [4 %]
Parameter [Scale 3] set to [36 %]
Parameter [Scale 4] set to [50 %]
Parameter [Scale 5] set to [100 %]
Parameter [Amount] set to [459 %]
Parameter [Small Detail Bias] set to [91 %]
Deconvolution, default parameters except for Parameter [Radius] set to [2.3 pixels]
Using 'Decon' preset in the Auto mask generator for the star mask (remember to invert).
Life module;
Isolate preset with Parameter [Strength] set to [54 %], Parameter [Mask Fuzz] set to [5.8 pixels]
Created a mask with the galaxies in them (see image) using the lassso tool ('Brush mode') in the mask editor;
Color module;
Parameter [Bottom End Saturation] set to [3.00]
Parameter [Top End Saturation] set to [9.90]
Parameter [Saturation] set to [325 %]
Parameter [Blue Ratio] set to [1.51]
Parameter [Green Ratio] set to [1.72]
Switching Tracking off, final noise reduction;
Parameter [Scale 1] set to [100 %]
Parameter [Scale 2] set to [88 %]
Parameter [Scale 3] set to [80 %]
Parameter [Scale 4] set to [70 %]
Parameter [Scale 5] set to [53 %]
Parameter [Color Detail Loss] set to [196 %]
Parameter [Brightness Detail Loss] set to [58 %]
Parameter [Intelligent Despeckle] set to [96 %]

From there I killed the background noise a little. I created a mask again with the galaxies in them (inverted so galaxies are protected).
Wavelet De-Noise
Parameter [Mask Fuzz] set to [6.6 pixels]
Parameter [Brightness Detail Loss] set to [56 %]
I then used the layer module to desaturate the background in the darker parts of the image (with galaxies still protected);
Parameter [Layer Mode] set to [Desaturate fg (Luminance)]
Parameter [Brightness Mask Mode] set to [Where fg is light, use bg]
Parameter [Mask Fuzz] set to [37.1 pixels]
Parameter [Brightness Mask Power] set to [0.30]

I ended up with this;
Of course, this is just one way to process it and you may like other values/procedures.
Hope this helps!

That is awesome Ivo. Thanks for the detailed play by play. Your processing of my picture also gives me a benchmark to compare my results against. I am still learning my new mount so I hope to get some better starting data once the clouds clear. Thanks again.

Jeff

Jeff2011 wrote:That is awesome Ivo. Thanks for the detailed play by play. Your processing of my picture also gives me a benchmark to compare my results against. I am still learning my new mount so I hope to get some better starting data once the clouds clear. Thanks again.

Jeff

No problem. Looking forward to your images!