LRGB stacking - auto-detect filters

[Clouzot]

Hi Han,
For the sake of science, I'm trying to stack my first short LRGB capture within ASTAP.

The material I have at hand is
- Lights: 20xL, 10xR, 10xG, 10xB lights. The FITS header contains the "Filter =" tags accordingly
- Individual matching darks
- Individual flats (30 per filter)
- Individual darkflats (60 total) matching the exposure/gain/offset of the flats

...so, normally, everything needed to achieve an LRGB stack, unless I missed something evident.

I added the various frames to their respective tabs, used the "Replace checkmarked with Master***" to get a single master dark and four calibrated master flats (one per filter). That went fine.

Now, I have all the lights analyzed and the worst ones are rejected . All fine, save for one small detail: I don't see the color square in front of the filter tag, contrary to what your screenshots show in the documentation.

The issue is then with LRGB stacking: either I check "classify by image filter", in which case ASTAP will stack the Luminance frames then will stop complaining about the absence of RGB frames, or I uncheck it, in which case ASTAP does a mono stack of all frames, including the color ones. What settings should I use to have ASTAP stacking the four layers as expected?

Thanks!

[Clouzot]

I'll answer my own question: both the "classify by image filter" and "flat filter" had to be checked before stacking.

[han.k]

Hello Clouzot,

Good you have fixed it . Did the rectable coloured boxes appear? Maybe something due to the Mac version

Regards, Han

[han.k]

The coloured indication rectangles are missing in the Mac version. I have to investigate.

[han.k]

These missing rectangle icons are a problem of the compiler and reported. I'm just waiting for somebody who has time to fix it:
https://gitlab.com/freepascal.org/lazarus/lazarus/-/issues/39193

[Clouzot]

Thanks Han, indeed the rectangles do not show in the table that contains the list of frames (under the Lights and Flats tabs), but I don't see that as a serious issue, unless they mean something else than just a visual reminder.

While I have you, if you don't mind: say I have multiple sets of those LRGB frames, each belonging to one pane of a larger mosaic. What could be the best way of stitching them using ASTAP's mosaic feature? Is it better to stitch the combined LRGB, or rather to stitch each channel (R1 --- R2, L1 --- L2, etc), then combine the four stitched channels into a larger image?
(there are complex things involved, gradients, background levels, channel balancing, etc, so I don't know what order is best)

[han.k]

I assume stitching LRGB will be more efficient but please try it. The image stitching routine is not perfect. It is very difficult to get smooth boundaries especially for colour images. Sometimes it is better to use the Microsoft Image Composite Editor (ICE) program but that is only for Windows available and it is no longer officially available.

I haven't looked to the stitching routine for some time. If your having some problem, please tell me and I will have a look.

[Grimstod]

Yes I to have noticed that the color icon does not show anymore. But I have been using the Designations S H or O for my narrowband stuff. I think it did work in a much older version but that was over a year ago.

[han.k]

Hello Grimstod,

Yes I to have noticed that the color icon does not show anymore

These missing rectangle icons are a problem of the compiler and reported. I'm just waiting for somebody who has time to fix it:
https://gitlab.com/freepascal.org/lazarus/lazarus/-/issues/39193

Maybe it worked a year ago but not currently

Cheers, Han