How to save, share and edit STELLINA images

Whether you are a beginner excited to share your exploration of the universe or a more experienced and demanding amateur astronomer, STELLINA‘s got you covered and can satisfy everyone’s expectations.
Three methods are available to save, share, and edit the results of your observations.

ABSTRACT

1. JPEG for instant results: save or share what you see on your screen

2. TIFF for manual image processing: raw images that you can edit by yourself

3. FITS for astrophotography experts: stack and process raw images yourself

The Carina Nebula captured with STELLINA. Image processed from the exported file in 16-bit TIFF. Image credit: Sébastien Aubry

For a better understanding

STELLINA runs a real-time image stacking process. While you are observing a celestial body, STELLINA keeps capturing new images and adds them to a “stack” to build up the final image you are visualizing. This is a commonly used process in astrophotography. Its goal is to improve the quality of the final rendering by reducing noise (a spurious signal generated by the electronics of any sensor that is randomly distributed over the image) and by highlighting the faint areas. For this reason, the longer you observe, the more the image quality improves, as shown in the video below.

fig.1: As your observation keeps progressing, STELLINA improves the image quality in real-time.

In this article, we will call each individual image that is captured and stacked together a “frame”.

Other than the very first image displayed when STELLINA starts capturing, you can’t see the unstacked single frames, but only the image built up from all the pictures that have been added to the previous stack. However, it is possible to retrieve all the single frames for a specific use, as you will see later.

Each single frame refers to an exposure of ten seconds. When STELLINA recommends an observation time of 30 minutes (1800 seconds), this means you will have to collect 180 ten-seconds exposures (1800 divided by 10).

Note: The Moon, the planets, and the stars available via the Stellinapp object index are displayed live. There is no stacking done on these objects.

1. JPEG for instant results: save or share what you see on your screen

Overview

The image displayed on your smartphone or tablet is the result of the stacking process carried out by STELLINA’s software in real-time. Our image processing algorithms automatically improves image quality and help enhance the details.

How to save the file?

Click on the “Image” icon on the top right corner of the Capture tab. You will get several options (figure 2).

fig. 2: The Image menu and its export options

You can:

Share STELLINA images currently displayed right on social networks,
Save the image in Stellinapp,
Save the image into your mobile device’s photo album.

If you plan to edit or share the image later, we recommend that you save your photo in your device.

You can save STELLINA images at any time during your observation. You can also automatically save all generated images by plugging a USB memory stick into the battery compartment prior to beginning your observation. STELLINA will detect your USB stick and will ask you to choose the image format you would like to save (figure 3). Choose the “JPEG” format.

Fig. 3: STELLINA Saving options on a USB stick.

How to use the file?

After your observation, you may be tempted to edit your image to improve the colors or try to bring out more details. Actually, as soon as the image is saved, Stellinapp will offer you some basic settings to adjust the image to your needs.

In case you want to edit the image in a graphics software, please note that the actions you can perform are limited and may degrade the image quality. There are several reasons for this:

STELLINA’s jpeg images have already been processed.
STELLINA images are saved in JPEG format: in order to reduce the weight of this well-known format, a digital digital compression is applied. This compression leads to barely perceptible changes to the pixels of the image. Running a deep processing on a JPEG image will bring out those imperfections (sometimes called “compression artifacts”) and eventually degrade the image quality (Figure 4).

In order to get a better image than what you see on the screen, STELLINA offers a second format you can use to pursue manual image processing: TIFF files.

Fig. 4: Zooming in on the detail of an image. On the left: raw image – On the right: JPEG compression where artifacts appear (for example, around the stars).