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Topics - alcol

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General / register new images with existing ones
« on: 2018 June 19 11:18:22 »
Hi folks, looking for advice.

If I have a batch of images that I calibrate, register and integrate. Can I save one of the registered images from this batch so that if I take more images at a later date I can simply register them against the saved registered image from the earlier batch?

Thanks for clarification.

General / Gradient Merge Mosaic error message
« on: 2018 February 05 12:26:59 »
Hi Folks help required.

I have been successful in the past with mosaics but I seem to have run into trouble with the 4 part HA Rosette nebula. I have cropped the 4 integrated images and ran through the mosaic process (in fact 2 or 3 times) all seems well until I put the images into the Gradient Merge Mosaic tool and it gives me a message "Error: Current image width differs from first image width.
<* failed *>
Checking the 4 image sizes I get 8445 x 6302  8445 x 6301  8446 x 6301  and 8445 x 6301  before starting the mosaic process all 4 images were identically cropped.

Anyone any idea where the process may have changed the image sizes? I followed Kayron's tutorial at


General / combining images from different scopes and cameras
« on: 2018 January 04 08:34:05 »
Hi folks

Any feedback on the following would be welcome. I have a number of Ha subs taken last year some from an Atik383 camera and some a ASI1600 both on  an ED80 scope (unfortunately the 2 batches rotated by 90 degrees). I recently decided to produce a 4 part mosaic of the Rosette Nebula used the ASI1600 camera on an ED120 scope and wanted to add the data gathered last year.

I read up on how to combine the subs simply using StarAlignment and ImageIntegration.  I have attached the view of the various subs. The 2 images on the left are from the 2 batches subs taken last year with the ED80 scope and the one at top right is a sub of 1 part of the 4 part mosaic taken on the ED120, there are obviously also 3 other sections (not shown). The image, bottom right is the integrated image of all the subs, this is produced using the top right part mosaic sub as the reference image. The other 3 sections of the mosaic would be integrated in the same way.

What I don't quite understand is how to get rid of the various shades of mainly background in the integrated image? It could be cropped out but it would get very close to the nebula in places. Using DBE as the next stage without cropping out the various shades of background would presumably cause some distortions to the image?

Advice on how to progress the mosaic would be appreciated

General / using workspaces
« on: 2017 November 03 14:04:30 »
Just started to put imaging files etc into Projects and decided to split data and processing into a number of Workspaces.
My first project involves a 3 part mosaic so I decided to put images for each part in a separate Workspace and renamed them mosaicpart1, mosaicpart2 and mosaicpart3 plus a 4th workspace renamed "masks". Saved the whole lot as a Project.

However, I then set up another project for an LRGB image and set up 2 Workspaces  "Limage" and "RGBimage" and saved it.

When I open either of the projects all 6 Workspaces set up open in the window, albeit only the data relevant to the project opened appear in the relevant Workspace and the others are empty.

I thought opening a Project would only open the Workspaces relevant to it?

Am I missing something?

General / add more calibrated images?
« on: 2017 September 07 12:17:56 »
A simple question that I am unsure of the answer.

I took 20 of images of M31 a few weeks ago, calibrated them and integrated them into an image (say image A). If I take more images of M31, same setting, and calibrate them, can I register them and integrate these addition images directly with Image A or do I integrate them with the original 20 calibrated images?

Thanks for your help.

General / DynamicPSF problem
« on: 2016 September 06 12:46:52 »
Probably something simple that I am doing wrong.

Selected a good number of stars from my Linear image, sorted them by MAD, A and r, deleted some as per the tutorials. Those that are left I Export, but the PSF image looks to be only 1 pixel in size and does not resemble a star.

Any ideas on what I am doing wrong?



General / Use of SubframeSelector on more than one batch of images
« on: 2016 September 04 10:20:22 »
My query is directed to Mike Schuster who wrote the PI Script:

If you take a batch of images say today, calibrate them and then run them through SubFrameSelector and save them with a weighting for noise, focus etc. If I subsequently did another batch of images at a later date, calibrated them and checked them in SFS would I need to run the earlier batch through at the same time to ensure that the weighting would be set against all the images in the 2 batches? Or do the weighting applied to the individual batches hold up when the two batches are integrated to produce and image?

Thanks for your help


Hi there

Can someone point me in the direction of information on how to use the Linear Mask in the MultiscaleLinearTramsform tool. I have tried and failed to get it to work. Probably very simple but I can't get it to work.



General / bright colour mosaic?
« on: 2015 September 21 05:21:49 »
Hi folks
More advice required.
Have taken 5 images of the Milky Way with a view to producing a mosaic. DSLR camera used.
I have calibrated, debayered, registered and integrated each set of images. Then cropped and ABE each one. Ending up with 5 images.

When attempting to merge the first 2 images using the simple process set out in Steve Allan's tutorial (, the 2 images clearly overlap and I duly end up with a mosaic, however it a brightly coloured mosaic. See attached.

Any advice would be welcome



General / more trouble with flats
« on: 2015 September 17 12:50:24 »
Looking for guidance

I have followed the tutorial regarding pre-processing. Used my super bias and master dark to calibrate my flats (taken by imaging a laptop screen with Notepad filling the screen) Up until a few weeks ago I didn't bother with flats as the DSLR camera was clean, now I have a large dust mote somewhere in the imaging train and I need to remove it with flats.

I have the following problem. When using the super bias, master dark and the master flat produced I get a very red image. The image is still bright red after using the Screen Transfer Function, with a hint of stars showing through. Using the Background extractor shows the image, but it still has lots of reddish gradients which I can't get out using post-processing techniques.

If I calibrate the Lights only using the super bias and master dark and no master flat, I get what looks like normal images. The bright red has all gone. However, with no flats applied the dust mote is in evidence and spoils the image. The Master Flat produced after calibrating with the bias and darks does show up the dust mote, but somewhere it is destroying the calibration of the Lights.

The images are still bright red if I only use the super bias and the master flat. Calibrated the Flats just using the super bias but still end up with the bright red image!

Any assistance, guidance would be very welcome. Please don't be too technical and PI is relatively new to me.


General / integrated image bright red??
« on: 2015 September 15 02:11:02 »
Hi folks

A newbie question

Just calibrated, registered and integrated some images of M45 and the integrated image is bright red with the stars showing through when I stretch it. The image looks rather like a Mask image. Applying DBE produces a more normal image, albeit with a red tinge about it.

Images taken with a DSLR camera ISO 800 Exp 300s

Can someone explain what is going on, why the integrated image is so red?



General / merging images for mosaics
« on: 2015 August 25 08:47:10 »
Hi everyone

Just discovered Steve Allan's superb video to create a seamless supermosaics. As a newbie I have a question.

I assume the individual subs forming the master images that will form the mosaic will have already been calibrated, registered and integrated? My question is this: these master images will still have gradients, will these show up when they are combined as a mosaic, presumably the GBE tool will need to be used on the individual master images before combining them into the mosaic?

Apologies for the newbie question, never produced a mosaic before.


General / RAW (CR2) images rotating
« on: 2015 August 19 07:04:42 »
Hi folks

Grateful for any feedback on the following issue. I am imaging with a Canon 550d DSLR and saving the RAW CR2 files on a laptop. I took 25 300s images in a session and viewing them on the laptop they were all in landscape 5202 x 3465 pixels. As I process them on a desktop, I transferred them via me home network. On opening them with Pixinsight, the last 8 images had been rotated 90 degrees and were now in portrait  3465 x 5202 pixels. I subsequently transferred them on a memory stick as I wondered whether it was the home network changed something. Same result.

As they have rotated I can't get Pixinsight to handle them and combine them with the other "landscape images". Rotating them gets them in the correct orientation but when looking at them with Screentransferfunction they change colour. On rotating they also become much larger files.

If I open the RAW CR2 files after transferring to my desktop using Windows Photo Viewer, they are still in the original Landscape 5202 x 3465 orientation. Why is Pixinsight seeing them rotated?

Anyone any ideas? Should it be possible for Pixinsight to combine images of different orientation and if so how. I normally get the "different geometry" error message

Thanks for help.

Note: All the images were taken in the same session and the same workplan on the Canon and the Canon has auto rotation turned off

Hi folks

Not sure what is happening but.

I have taken light images and have them stored on my laptop. They are orientated in landscape and show up as 5202x3465 pixels.

I transfer the Lights to my desktop for processing on PI and for some reason they get rotated through 90 degrees and appear as 3465x5202 pixels. When i try to calibrate with darks etc I get an incompatible geometry error message. 

Help urgently required



General / Pixinsight can't see xisf files
« on: 2015 July 16 04:43:37 »
Hi folks

I have the trial version and its been behaving itself for the first couple of weeks. I must say it is very impressive.

However, turned PC off last night and turned on this morning and when I go to open an xisf file with PI it can't find any xisf files. They are in the folder because I can see them. xisf is not listed as one of the "All known file formats"

Please don't send me to Q & A because I have been there and can find no answers.

Help please as I am now at dead stop and can do no processing



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