Select the base image to get the best possible view of the sky and the meteors

Select the base image to get the best possible view of the sky and the meteors

One of the things that traditionally had to be done when processing a meteor shower image was to first choose the base image on which to align the captured meteors.

However, the great disadvantage of this was that before seeing the final result (with all the meteors aligned on the sky of the base image) it was impossible to know which one (among all the captured images) allowed to obtain the best result.

In order to choose the best possible base image, it should first be possible to see the result generated by all of them. So precisely for this reason Nebulb does not allow to select the base image before stacking (the software selects it automatically, because before processing the images it is not possible to know which one will be the best).

But what Nebulb does allow is, after stacking, to select the base image in a very visual way (showing instantly how the meteors are positioned for each moment of the night).


Modify the base image

These are the steps to follow to modify the base image of the sky to get the final image with the best possible composition and visual impact.

1. Initial result

By default Nebulb always selects as initial base image (on which it does the stacking) the one that is chronologically in the middle of the total capture time.

Final image obtained with the base image initially selected by Nebulb (the one right at the middle instant).


2. Activate the rendering of meteors in "line" mode

Rendering the meteors in "line" mode is the most suitable way to visually check how the sky (and therefore the meteors) moves when changing the base image.


3. Select the time of the night when you like the position of the meteors the most

By moving the lower time slider, the rendering of the meteors in the sky shows, immediately, how the meteors would be aligned according to the sky at that precise moment of the night. In this example, by positioning the time slider at 1:10:27h of the night, it is observed that there is a meteor that is aligned just in the upper right corner, so it is decided to select this time of the night as the base (by pressing the yellow arrow button).


4. Select the new base image

By clicking on the button to select a new base image (yellow arrow) the sky displayed matches the sky at that time of the night and, in addition, the position of all meteors has been recalculated to be rendered according to this new base image.

And when you activate the rendering of the meteors in "real image" mode, you get a final image different from the one you had initially. Having selected another base image (the one captured at 1:10:27h) the sky is shown as it was at that time of the night and the meteors also appear aligned according to that instant.


5. Refine stacking to reduce noise (if necessary)

When selecting another base image it is possible that noise appears again in the sky, since, due to a computer resource consumption issue, it is not possible to apply noise reduction by stacking for all the moments of the night (in case an equatorial mount has not been used and the sky has changed a lot).

However, to solve this problem and get a completely noise-free image (for any time of the night) you can perform a stacking refinement, which is nothing more than a small stacking on the image selected as a base to reduce its noise.

In this other article you have more info on how to perform a stacking refinement: https://help.nebulb.com/portal/en/kb/articles/refining-the-stacking


Multiple results for the same session

Once the stacking is finished you can modify the base image as many times as you want, so you can obtain many different results from the same meteor shower session.

Thus, below you have another result obtained from the same meteor shower session of the previous example (just having modified the base image again):

Final image obtained by selecting as a base the image captured at 5:29:03h of the night. At this time of the night the radiant of the 2023 Perseids was just at the upper limit of the frame, giving a different look to the final image.





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