Histogram Stretch

Image processing, astrometry, photometry, etc.
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Dave_S
Posts: 53
Joined: 11 Oct 2021, 10:09

Histogram Stretch

Post by Dave_S » 26 Feb 2022, 15:23

Can I apply a Histogram Stretch setting to a batch of images, as opposed to applying it to each image individually, and then saving each one before preprocessing (cal, alignment, and stacking etc) to produce a master image with the chosen Histogram Stretch setting?

For example, I have a batch of 30 subs as output from camera, open in AA8. I can adjust the 'stretch' on the first image, to how I want it, using the' scroll wheel' on the 'mouse'.

Can I apply this 'stretch' setting to the other 29 images, automatically as a 'batch', or do I have to apply it manually to to each image in turn.

I'm sure there is a way within AA8 to do this, but as yet, I can't see how.

Iver
Posts: 103
Joined: 08 Jan 2019, 04:32
Location: Monterey county, Ca.

Re: Histogram Stretch

Post by Iver » 26 Feb 2022, 16:51

I've always applied the stretch to the combined image. Would there be anything to gain by stretching the individual subs ?
Iver

Dave_S
Posts: 53
Joined: 11 Oct 2021, 10:09

Re: Histogram Stretch

Post by Dave_S » 26 Feb 2022, 20:24

I tried that Iver, but it didn't work, as once stacked, the data that I can recover from a single sub is lost, and I now find that adjusting the image intensity using the scroll, the resulting image view cannot be saved.

What I am trying to do, as I always did back in the day, is to layer combine two M42 images in photoshop. Once exposed for the core, and the other for the outer areas.

In this case 10s for the core, and 90s for the outer area (IMX 294c Camera.

In 10 sec exposure presents with the core burnt out, but the data is still there, and by using the scroll wheel, I can bring the core data into view, but can't save this 'view'. Save View just saves the unadjusted image.

Two examples of the same image below, one as returned from the camera, and the other with the screen view turned down with the scroll wheel, and that is the one I want to apply to the rest of the image stack, before combining, but there doesn't seem to be a way of doing this in AA8.

The only other answer is to try imaging the M42 core with 5s or less exposure, or backing the camera gain right off. Never had this problem with CCD cameras.

Iver
Posts: 103
Joined: 08 Jan 2019, 04:32
Location: Monterey county, Ca.

Re: Histogram Stretch

Post by Iver » 26 Feb 2022, 21:16

Which stacking method did you use?
Iver

Dave_S
Posts: 53
Joined: 11 Oct 2021, 10:09

Re: Histogram Stretch

Post by Dave_S » 26 Feb 2022, 22:01

Sum.

Dave_S
Posts: 53
Joined: 11 Oct 2021, 10:09

Re: Histogram Stretch

Post by Dave_S » 27 Feb 2022, 13:28

All sorted now :)

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