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Messages - drmikevt

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Gallery / Re: NGC 7822 / Ced 214
« on: 2017 July 04 14:07:25 »
Masked Stretch and S-curve

Gallery / Re: NGC 7822 / Ced 214
« on: 2017 July 04 14:06:38 »
STF and HT

Gallery / Re: NGC 7822 / Ced 214
« on: 2017 July 04 14:05:03 »

Thank you!  I've been struggling myself.  I'd like to get to a place where I can dial in the 'turquoise and gold' motif that I see some people produce, but that (currently) seems most easily done in the 'that other program'. 

For this (and all my processing) I follow Vincent's advice:  SHO maps to RGB in Channel Combination.  Then, DBE, BN and Color Calibration using an area of the nebula that is well represented by the 3 filter lines for white (without structure detection, of course).  I usually will select 3-4 different areas of 'background' and 2-3 different 'white' areas and then combine them in various ways using Color Calibration.  It is sometimes amazing how different the hues and contrast can be when using different previews.  I will tile all the new Color Calibrated images on the screen and compare them to select the one with the richest color and contrast.  I try hard to get the best color possible from the get go.

Then, for stretching, I'm starting to experiment Masked Stretch instead of HT for color.  The image above, though was stretched using STF settings transferred to Histogram Trans.

The real work comes after stretching with the Color Mask script.  This is also something I am just learning, but seems to be the key to adjusting colors for NB image with any sense of control.  Simply following the steps on this page,, work very well to get to a better image, and to help understand how the script works.  I have found it is important to use previews to get zoomed-in views to make sure you are not over-saturating anything.  Then, I will do some further color correction using Curves with and without a masks.  I have not had great success with the AIP scripts. 

Below are 2 more posts.  The first is the data stretched with STF (Target Background .28-3 and Shadows Clipping at -2 to -1.5) and HT.  The second is the same data (preprocessed a little differently, but still) put through Masked Stretch at .28 target background and .03 clipping percentage, and then given a small S-curve.  In both cases, no other color manipulation was done outside of Background Neutralization and Color Calibration.  Both were stretched to put the peaks at around .28.  As you can see, there is a dramatic difference in the two results.  In the first case, using just BN, CC, STF and HT, you get pretty close to the image I posted.  How are you trying to do it?   I am just about to start working with the MS stretched result to see what I can do with the much more intense colors.  I'll post results in a few days. 

I'm still learning every day, and you certainly know tons more then me, and I don't mean to tell you things you already know, but I hope this helps.

Gallery / Re: NGC 6823 Bicolor
« on: 2017 July 01 09:40:00 »
Both are nice.  Can you speak a little to how you like to de-noise the nebula areas?  Yours are very nice and smooth (but not overly so).

Gallery / NGC 7822 / Ced 214
« on: 2017 July 01 06:51:42 »
This image represented my first ever start to finish SHO image captured from my backyard.  I'm very happy to finally be at this point.

I know many people prefer a less colorful interpretation of the SHO palette, but I like these colors to better differentiate the filter lines. 

Larger one

QSI 683wsg-8

Comments and constructive criticism appreciated.

General / Readout mode default
« on: 2017 June 30 16:02:17 »
I can't seem to get back to the default settings in Readout mode (I don't know what they are).  Currently, my K values for bright stars are in the .00xx range and background is just zero.  I want to get back to a setting where the K value is consistent with Noise Threshold setting in Star Mask, for instance. 

Any help is appreciated.  Thanks.

General / Re: TGVInpaint for star removal?
« on: 2017 June 19 21:02:10 »
I am on a Mac so I'll have to skip it.  Thanks, though. 

TVGInpaint sounds similar in function to Morph Trans in Erosion, no?

General / TGVInpaint for star removal?
« on: 2017 June 19 19:31:53 »
I am reading about this process in some posts from last year.  I am looking to improve star removal techniques (if anyone has a recent tutorial, I'd love to know about it).

I can't find this process in the current build - is it still available?


General / Re: Pixinsight image is darker than web and Ps.
« on: 2017 March 19 08:33:37 »
If you are comparing images in their linear form, then it almost certainly has to do with the auto-stretch settings of your Screen Transfer Function process.  Open that process and command or control-click on the radioactive symbol.  Adjust the target background upward and your images will now all be a bit brighter on the screen.  This does not affect the actual image - just how it is displayed on the screen.


General / Judging Dark/Bias rejection levels....
« on: 2017 March 19 07:36:03 »
I'm wondering about how to most properly make a bias or dark master frame.  When working with light frames, it is important to adjust the rejection parameters so that only the problematic pixels are rejected.  This creates a rejection_high frame that is sparsely populated with pixels rather than an image full of 'snow'. 

When creating dark/bias frames, do we do the same?  Or is it best to leave the rejection parameters at default, even when working with large numbers of frames (like 300 bias frames)?

While we are at it, the page on this website about master calibration frames ( says to use 'No Normalization' for pixel rejection, but I have also heard (from Vince Peris) that we should be choosing 'Scale and zero offset'.   Which is correct?

Thank you for all input

Off-topic / Re: Noise evaluation script
« on: 2016 December 24 09:39:28 »
Thanks, I understand. 

But still, if we use the instructions here: we can get very different results than if we use Linear fit, which usually results in a higher noise value (# of pixels), but perhaps that is what we want...?  I'm guessing the tutorial outdates Linear Fit so is that the correct setting for integration (assuming 50 frames) now?

I'm sure this discussion has happened before, but there must be a way to determine an optimal dark or bias from a set of iterated images.

Again, all input is greatly appreciated

Off-topic / Re: Noise evaluation script
« on: 2016 December 24 08:02:47 »
So, would it be possible to use this script to compare dark frames integrated with different settings (winsorized sigma vs linear clip, different sigma high settings, etc) to see which one is 'best'?  Assuming that the lowest noise image would be generally best...? 

If this is not the right tool, how do you determine the best dark frame in a group? 

Thank you for all input.  I just finished a workshop with Vince and I'm trying to look at things with a finer lens now.


General / Re: DrizzleIntegration crashing on Mac
« on: 2016 November 13 17:38:25 »
Yes, thank you for the quick response - very appreciated!


General / DrizzleIntegration crashing on Mac
« on: 2016 November 12 14:02:06 »
I just updated Pixinsight today with the latest recommendation and now DrizzleIntegration crashes the program when it runs.  I've restarted everything, etc.  I'm on a Mac, OS 10.11 (not the newest one).  Anyone have a similar issue?

Otherwise, the program seems to be working fine...


Gallery / Bubble Nebula Mosaic - Metsavainio method
« on: 2016 October 29 11:43:46 »
Hello - in the spirit of bitting off more then I can chew, here is my first ever attempt at both a mosaic and narrowband processing.  Previously, I had only worked with LRBG.  Any and all comments are appreciated.  I have not been able to find a similar photo, so I'm not sure what it is 'supposed' to look like.  It is made from a staggering amount of data (50hrs) gathered by Deep Sky West. 

I'm signed up to take the 6 day class in December - I wonder what it will look like after re-processing after that class.



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