Sometimes there’s wind during your observation and your image is good, except for elongated, smeared, or blurry stars. You could try this technique in Photopea.com to try to recover your image.

Here’s an example of an image having smeared stars in it:

The stars throughout this image are not round as a result of movement of the telescope during the observation.

This is the image after performing a simple adjustment that I explain below:

The stars in this image are more round than before and note that some of the stars have diminished as a result of the adjustment, but the image is still quite good.

Correct Elongated, Blurry, or Smeared Stars using Photopea.com

Use the following directions:

  1. Point your browser to Photopea.com
  2. From the menu, select File – Open and open your image
  3. From the bottom-right side of the window, right click the Background layer and select Duplicate Layer


  4. Where it says ‘Normal’, select the dropdown and select ‘Darken’



  5. From the menu, select Filter – Other – Offset



  6. Modify the values in the Horizontal and Vertical boxes by entering a value (do not use the slider) – it’s recommended to select small values (start with 2-4 pixels for each):


  7. Adjust the values until you see that your stars are round and then click Ok to accept the change

    Adjust using the Horizontal and Vertical offsets – take a look at the stars in your image to determine which offset to use – you may have to use a combination of vertical and horizontal offsets.
  8. From the menu, select Layer – Flatten Image
  9. Save your resulting image (from the menu select File – Export As and select a format; your file will appear in your browser’s downloads folder)

This adjustment affects your whole image; there may be cases where you only want to affect some of the stars. In this case, use the elliptical selection tool to select the stars in your image (press Shift while selecting to select multiple stars), as shown here:

Next, copy/paste the stars (use the menu or press CTRL + C and CTRL + V). By pasting the stars, you create a new layer, as shown:

Follow the directions from step four above to complete the process on just the stars you selected.

Conclusion

In this article, you learned how to recover blurry or smeared stars in your astronomical image.