Star Alignment in 1.8.04.1171

[Rex]

Since I updated to the new version star alignment doesn't seem to work any more.

It goes through the process as if it is working, making star matches etc, but when it registers the images and outputs the result they are not registered, and the star positions have not moved to match the reference file to cancel out the effects of dithering.

 Attached is a copy and paste from the process console of the last image stats. As you can see the rotation dx and dy all say zero. This is the same for all 38 images and when you stack them you get a mess.

[Rex]

Hey guys I am not sure it is something to do with my system or not but I just realized when I open a linear image, do a STF on it and save the image it saves the STF to the image. Meaning that once I save the image, if I reopen it, it is no longer linear data, it is as if I have performed a Hist Trans to the image.

My system is an I7 4790 running windows 8.1. I have been running the previous version on this machine for a couple of months without any issue, so I don't think my system is at fault, but I am open to suggestions as to what may be causing these issues.
Thanks.

[jdupton]

Rex,

   I think you may be seeing the XISF format at work. It defaults to saving the "Display function" if an STF is currently applied when the Save takes place. The image is likely still linear.

   Try this - Open the image in question and then from the STF process window, do a Reset. You should see the linear appearance of the image return. It looks like the default for XISF saves is that if an STF is applied at the time of the Save, the display function check-box is active; if an STF is not applied at the time of the Save, then the Display function check-box is not active. You are given the chance to change it either way when you do the save.


John

[Rex]

Thanks for your reply John, however I had the STF window closed when I reopened the image. Unless somehow the STF settings are embedded in the image file I am not sure how it displayed a Screen stretched image when opened. And if this is the case I think it should be rethought. If it displays a screen stretched image while still linear data when first opened, how is the user supposed to know if the image is linear or not? Surely we are not expected to open the STF tool and do a reset on it to check before saving? Are we?

[jdupton]

Rex,

   Yes, the STF information is stored in the saved file. You do not need to have the STF process window open when you open the file. If you simply reset the STF with either the STF Process window or reset from the ToolBar, the stretched image will revert to the raw linear state. It has not been permanently changed by the save. It just defaults to the same level of screen stretch as when you saved it. The linear image was saved -- it was just saved along with the last STF state and that is what it shows when it is opened again.

   You can choose whether to save the STF info or not when you save the image. Just select or deselect the "Display function" check-box on the modal save window that pops up as you save the file.

   If you are ever unsure what state the image is in, just click the Reset button on either the STF ToolBar or the STF Process window. Any STF display stretch will go away.

   If you don't like this option of the XISF format, use the Format Explorer to change the default handling of the Display function state. (I haven't tried that but it should work.)


John

[Rex]

So the answer is yes we are expected to reset every time we open an image. Thanks.

No word on the Star alignment issue? I have a bunch of data that I would like to stack but cannot until this issue is resolved. As stated above it may be something with my set up or a setting that I cannot find but I am lost as to how to resolve it myself.

[mschuster]

No word on the Star alignment issue?

Rex, the developers are hard at work, there might be a bit of delay on any particular issue. I know it can be frustrating. It would help if you placed a zip of your frames and a saved StarAlignment icon xpsm file with your settings in Dropbox. Also you might want to deinstall the new version and reinstall the old one for the time being.

Thanks,
Mike

[Rex]

Hi Mike thanks for the reply. I appologise for the way that last post came accross, it wasn't meant as a dig at you guys. I was hoping for feedback from others (if anyone else has similar issue) so I could work out whether it actually is an issue with the software or something in my system. I just worked out that the batch preprocess works for registering, so although not ideal gets me out of trouble for now. Thanks again.

[Juan Conejero]

Hi Rex,

Since I updated to the new version star alignment doesn't seem to work any more.

StarAlignment works correctly in version 1.8.4 of PixInsight. Actually, the result you've got demonstrates it:

Transformation matrix:
     +1.0000     +0.0000     -0.0010
     -0.0000     +1.0000     -0.0002
     -0.0000     +0.0000     +1.0000
scale       : 1.000
scale-X     : 1.000
scale-Y     : 1.000
rotation    :     +0.00 deg
dx          :     -0.00 px
dy          :     -0.00 px
Generating registered image
Homographic Projection / Lanczos-3 interpolation, c=0.30: done
Registration successful.

Typically this happens when your images are being registered to hot pixels. Are you working with properly calibrated images? Anyway, try increasing the hot pixel removal parameter (Star Detection section) to 2 pixels.

[Rex]

Thanks for the reply Juan. I calibrated the images the same way I always do but anything is possible. I was about to load some images and a star alignment icon up to drop box as suggested by Mike. I will try your suggestion first and hopefully that will fix it. Thanks again for your help.

[Rex]

Hi Juan and Mike.  Thank you both for your help. Juan  i tried what you suggested but it still didn't work for that set of images. However I tried a different set of images and it works perfectly, (don't know why I din't think of trying this before i posted). I feel like an idiot and i appologise for taking up your time at such a busy time for you. I have no idea what is wrong with that set of images but I now know that the problem is with the images not the software. Thanks again for your help.

[Cosmick]

So the answer is yes we are expected to reset every time we open an image.

When there is a Screen Transfer Function active on the image Pixinsight will notify you of this by displaying (by default) a green line on the Identifier tag of the image. You can turn STF on and off from the toolbar without opening the dialog.