Two or Three Stars Registration (deep-sky)

This method is particularly well-suited for lucky imaging, as it does not require as many stars as Global alignment but can cater for rotations between frames.

Thanks to two or three stars being used, images are aligned using a similarity transformation, i.e. two shifts on X and Y, one rotation and one scale.

Tip

A new sequence is created as an output to this step.

If the initial sequence was a CFA SER opened with Debayered option checked, the resulting SER is a RGB SER.

Screen

  • 1⚓

    Layer on which the registration is done.⚓

    It can only be done on one layer at a time.

    Tip

    The (*) sign appearing after the layer's name means that registration data is already available for this layer.

    Note

    When processing images, registration data is taken from the default layer if available (for RGB images: Green, else fallback to Blue then Red).

  • 2 Pick stars⚓
    Pick stars

    Draw a box around a star and press Pick 1st star. Siril will compute the position of this star along all the images of the sequence (the same process as one star registration is applied when Follow star movement option is selected).

    Once completed, draw a box around another star and press Pick 2nd star.

    After completion, you can optionally select a third star and press Pick 3rd star.

    Tip

    While the process only needs two stars to compute the registration, adding a third star will either increase the accuracy of the transformation computed or compensate for missing stars if a star has gone missing on some frames.

  • 3 Simplified Drizzle x2⚓
    Simplified Drizzle x2

    Use this option to upscale the images by a factor of 2.

    Warning

    With this registration method, a new sequence is created. If this option is selected, the new images will be four times a big as original images, which may take a lot of space and require more time to compute.

  • 4 Go register⚓
    Go register

    Once enough stars have been selected, the Go register button will be enabled (blue-colored) and the new registered sequence can be computed.

    The new sequence name will be prefixed with 'r_' by default. It can be changed by displaying the corresponding text field when selecting the global star registration method.

Extra⚓