Dark lane artifact in reconsttructed image from otherwise normal .ser file

[smart-underworld]

I noticed in the last 2 version (currently 2.5.2), many of my .ser file when processed has a dark band in the reconstructed image. I re-analyzed the exact same file with INIT and got typical reconstructed image as expected. I attached one such result image processed by JSol'ex, and the .ser file and related data can be found in my shared folder:

https://drive.google.com/drive/folders/1peKBQRxkCbCpqkaDw9_pGZdOUB4dBbQV?usp=sharing

[melix]

The issue is that there are simply no 15 pixels to use when reconstructing the image. This can be seen in the spectrum debugger:

One option is to use -15 pixels in your case, instead of 15. I should add a warning in this case and reduce to the maximum usable shift.

Note also that your gain is probably too high, you are loosing a significant part of the dynamics.

[stefanoaz]

Hi Cèdric:

I often use negative pixel shifts to avoid the banding in the continuum. But it wouldn't be a good idea to restrict the pixel shifting to 15, for those with 2µm pixels. 15 pixels is too small an offset from H-alpha to produce a continuum free of H-alpha details. If I see a single band or a bright section of the disk near the edge in the continuum, I immediately look at the pixel offset and adjust it - in the negative direction if necessary.

steve

On Jun 30, 2024, at 08:02, Cédric Champeau @.***> wrote:

The issue is that there are simply no 15 pixels to use when reconstructing the image. This can be seen in the spectrum debugger:

image.png (view on web) https://github.com/melix/astro4j/assets/316357/4840349b-2eb9-4c42-bf09-b3ae9cc77f80 One option is to use -15 pixels in your case, instead of 15. I should add a warning in this case and reduce to the maximum usable shift.

Note also that your gain is probably too high, you are loosing a significant part of the dynamics.

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[melix]

Not sure what this comment means. You can adjust the continuum shift as needed. It is not limited to 15 or -15.

[stefanoaz]

You were saying "reduce to the maximum usable shift." I was concerned that you might go back to the 15 pixels of INTI. But I now suspect you meant that jSolEx would determine this from the spectral frame average and make a software-based decision, which seems like a good idea.

steve

On Jun 30, 2024, at 08:12, Cédric Champeau @.***> wrote:

Not sure what this comment means. You can adjust the continuum shift as needed. It is not limited to 15 or -15.

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