New User Quick Start

[sreilly]

I have no idea if this is of any value but a friend asked how I used PI and this was a better way for me to explain. Any feedback would be appreciated. See http://www.astral-imaging.com/pix_insight_a_new_user.htm

[RBA]

Yeah, you're missing a link to the unofficial reference guide  8)
http://blog.deepskycolors.com/PixInsight/

Simply unforgivable!!

[sreilly]

You are absolutely right! What a resource to forget. It's there now. Thanks for the reminder.

[Jack Harvey]

Nice work Steve!  I think this, along with the variety of other tutorials and videos is great.  Of course if you saw the SBIG thread you know PI is way too expensive and there is no documentation at all

[Juan Conejero]

Hi Steve,

Good job. I think deconvolution should go before the initial stretch, but there's actually no problem in using it for sharpening a nonlinear image, as long as you know that you're doing just that.

As Jack says, this is good material for new users. Thank you for your time and effort. We are also starting a series of new video tutorials right now, covering basic topics and step-by-step processing tasks. And I am starting to write more reference documentation again, too

As for other forums, discussion groups, etc, I decided to keep myself apart from them, long time ago. When the author of a software application participates in a public forum, other than his own support forum, it's too easy to start either acting like a door-to-door salesperson, or making desperate efforts to defend himself. Both are pathetic IMO. Only the software that we write must speak for ourselves, and only our projects must tell what we are and what we are capable of. Then there are people that want to hear our 'music' and people that don't. That's it. And that's fine

[sleshin]

Very nice job, Steve. Thanks for taking the time to do this. With regards to the HDR page, I think HDR Wavelets should be applied to non-linear images.

Juan, glad to hear you're working on new videos, look forward to their release.

Steve

[sreilly]

I think deconvolution should go before the initial stretch, but there's actually no problem in using it for sharpening a nonlinear image, as long as you know that you're doing just that.

I can see that but I don't understand how this is accomplished. I went back to my M74 image which is 20 - 20 minute luminance images that was calibrated, registered, and then combined using average and linear fit rejection. DBE was performed and the image saved. Saved that image as a 64 bit image and then opened deconvolution and tried 5 iteration of Regularized LR which resulted in a very molted looking image. Tried regularized Van Cittert as well as and had ringing around the stars even though deringing was check. This was simply opening the image and using the settings as seen here http://www.astral-imaging.com/pi_processing_decon.htm Difference is the 5 iterations instead of 10 and trying both RLR and RVC. I used STF to see the affect on the images. No mask was used. I tried with a mask I had made after HST was used before any of this and inverted the mask. Results were even worse. I guess I haven't a clue as to how to use this process other than sharpening as I was doing after HST. I've uploaded the 64 bit fit file to  www.astral-imaging.com/integration20L.fit if anyone wants to try and let me know what I'm doing wrong. This is a 23+ MB image. I tried to create a mask while in linear data and what I used was the same settings as after HST. The results while linear was that just a few bright stars were selected. I seem to get better masks using non-linear data. Is this to be expected or do I need to dig deeper creating masks on linear data? In other software I've used in the past, deconvolution was done on the entire image, no masks used. Is this preferable?

[Juan Conejero]

Hi Steve,

Take a look at this little tutorial that I made with an image by Sander Pool:

http://pixinsight.com/forum/index.php?topic=2727.msg18512#msg18512

A few things more:

- Masks for deconvolution must be created from a stretched image. Make a duplicate of your (linear) luminance image, stretch it and activate it as a mask for the original image. However, you'll find that masks aren't necessary in most cases if you use regularized deconvolution algorithms.

- 64-bit images are normally not necessary. We use them to store very large HDR compositions, and also in some special cases where we need very high numerical accuracy. For normal image processing purposes, 32-bit floating point (or 32-bit integer for even more accuracy) is sufficient.

- In general, the Van Cittert algorithm is not an appropriate choice for deep-sky images. Use regularized Richardson-Lucy (RRL) instead.

- 10 iterations of RRL are usually too few. For a linear image, we normally apply from 50 to 200 iterations, depending on the signal-to-noise ratio. The number of iterations is not critical though. Thanks to regularization the algorithm stabilizes and usually there's very little difference —if any at all— between 50 and 100 iterations for example.

Hope this helps

[sreilly]

Juan,

Thank you. This is the most through tutorial I've seen on using any process or tool. I asked about the process to obtain the PSF for deconvolution but until I understand that I've still been able to use your example and make great strides in a basic understanding of how the process works.

[dsnay]

Hi Steve,

Good job. I think deconvolution should go before the initial stretch, but there's actually no problem in using it for sharpening a nonlinear image, as long as you know that you're doing just that.

As Jack says, this is good material for new users. Thank you for your time and effort. We are also starting a series of new video tutorials right now, covering basic topics and step-by-step processing tasks. And I am starting to write more reference documentation again, too

As for other forums, discussion groups, etc, I decided to keep myself apart from them, long time ago. When the author of a software application participates in a public forum, other than his own support forum, it's too easy to start either acting like a door-to-door salesperson, or making desperate efforts to defend himself. Both are pathetic IMO. Only the software that we write must speak for ourselves, and only our projects must tell what we are and what we are capable of. Then there are people that want to hear our 'music' and people that don't. That's it. And that's fine

Wisdom. It's a beautiful thing that sadly usually only comes with age.

[dsnay]

It's funny how similar your workflow is to mine. I'm still a PixInsight rookie, but here's what I've settled on as a starting point.


Calibrate in Nebulosity (it just works better for me at this point}
Move to PI

• Align and Integrate color sets
• ChannelCombination to form RGB image
• Background Neutraliztion (maybe)
• Color Calibration (maybe)
• DBE (almost always - thanks to light dome of neighboring city)
• HistogramTransfer (several iterations)
• HDRWavelets (lots of experimentation on each image here
• ATrousWavelet (Just starting to play with this)
• Repeat DBE through at least HDRWavelets for the Luminance data
• LRGBCombination
• Off to Photoshop for final tweaks

For me, all roads lead to PS. In some ways PixInsight is both shortening and lengthening my overall path.
I've found that many of my tasks that required significant effort in Photoshop are easier (now that I'm starting to understand enough about PI to ask intelligent - I hope - questions). My path is shorter in that I'm spending less time in PS, but more time overall as there is more I can accomplish in PI.

Of course, if I were able to acquire better data my path would be significantly shorter. I once rented time on a really great setup in the Sierra's and processing that data took about 10 minutes.

Dave

[sreilly]

Calibrate in Nebulosity (it just works better for me at this point}
Move to PI

• Align and Integrate color sets
• ChannelCombination to form RGB image
• Background Neutraliztion (maybe)
• Color Calibration (maybe)
• DBE (almost always - thanks to light dome of neighboring city)
• HistogramTransfer (several iterations)
• HDRWavelets (lots of experimentation on each image here
• ATrousWavelet (Just starting to play with this)
• Repeat DBE through at least HDRWavelets for the Luminance data
• LRGBCombination
• Off to Photoshop for final tweaks

For me, all roads lead to PS. In some ways PixInsight is both shortening and lengthening my overall path.
I've found that many of my tasks that required significant effort in Photoshop are easier (now that I'm starting to understand enough about PI to ask intelligent - I hope - questions). My path is shorter in that I'm spending less time in PS, but more time overall as there is more I can accomplish in PI.

Of course, if I were able to acquire better data my path would be significantly shorter. I once rented time on a really great setup in the Sierra's and processing that data took about 10 minutes.

IMHO, the amount of time spent on processing an image should be a minor issue where the quality of the final image should be most important. As for your work flow, Background Neutralization, Color Calibration, and DBE all balance the color so these are redundant. I can't see you getting different results with each of these steps. If you have gradients then DBE, if properly applied, should take care of the gradients as well as balance the color.

The difference I see in the black point between PI and PS is about the only thing short of creating my web JPGs I use PS for unless I have a bit of noise I want to reduce. Then I use a masking routine in PS to selectively reduce color noise. That said, until I learn the proper way to do this in PI, it's an efficiency thing for me as I own both software's already. If I didn't already have PS I certainly wouldn't buy it for this as PI is extremely capable. As for the black point, I need to pay close attention as to where this is in both programs. As PI shows how much you are clipping it should be a simple matter of seeing where this shows on the levels in PS.

[dsnay]

IMHO, the amount of time spent on processing an image should be a minor issue where the quality of the final image should be most important. As for your work flow, Background Neutralization, Color Calibration, and DBE all balance the color so these are redundant. I can't see you getting different results with each of these steps. If you have gradients then DBE, if properly applied, should take care of the gradients as well as balance the color.

The difference I see in the black point between PI and PS is about the only thing short of creating my web JPGs I use PS for unless I have a bit of noise I want to reduce. Then I use a masking routine in PS to selectively reduce color noise. That said, until I learn the proper way to do this in PI, it's an efficiency thing for me as I own both software's already. If I didn't already have PS I certainly wouldn't buy it for this as PI is extremely capable. As for the black point, I need to pay close attention as to where this is in both programs. As PI shows how much you are clipping it should be a simple matter of seeing where this shows on the levels in PS.

I'm not sure I agree that Background Neutralization, Color Calibration and DBE are redundant. I agree that they don't all need to be used on the same image (and probably shouldn't), but they definitely seem to do different things.

My understanding (limited though it may be) is:

Background Neutralization will try to even out an overall color cast to the background, while leaving major objects alone.
Color Calibration will try to adjust colors throughout the image based on the models described elsewhere in these forums.
DBE is best used to eliminate color gradients.

These sound like three different goals which should be used when appropriate. In my case, it actually sounds like the Background Neutralization and DBE will be necessary in most images and color calibration will depend on how I feel about a given image.

As always, I am willing to be shown the error of my logic. After all, it's the only way I learn!

Clear skies!
Dave

[Astrocava]

I usually apply DBE before BackgroundNeutralization and ColorCalibration. Why? I think they will work better with a image without gradients. I usually have heavy chromatic gradients that will cause bad ColorCalibration if I don't apply a DBE first. If you have modeled the background for DBE with care and with enough samples, you don't need to apply BackgroundNeutralization.

So, I usually apply DBE and then ColorCalibration. For me these tools aren't redundant.

Have fun!

Sergio

[sreilly]

I'm not sure I agree that Background Neutralization, Color Calibration and DBE are redundant. I agree that they don't all need to be used on the same image (and probably shouldn't), but they definitely seem to do different things.

I thought you were using all three on the same image for color balance and therefore the redundant remark. Truth be told I'm a long way from understanding the proper use of most of these processes but gradually trying a little something new over time. The ATrouswavelet is something I'd like to try but haven't really looked at yet.