===== Tilt =====

//Tilt Geometry//

=== Tilt Geometry [det_tilt] ===
This is a switch, deciding if the tilt angle and tilt axis for this image should be determined, or if the image should instead be considered as non-tilted. It takes some processing time, which is not needed if you already know that the image is from a non-tilted sample. If the switch is set to "No", then the tilt geometry is not determined, and the tilt geometry values are not touched.

=== Which algorithm to use for Tilt Geometry from Defocus? [det_tlt_alg] ===
This allows you to chose which algorithm should be used to determine the tilt geometry from the defocus gradient in the image. The first option uses Niko Grigorieff's program CTFFIND3 on various (7x7) locations in the image, and then fits a tilted plane over all those determined defocus values. The second option uses Niko's CTFTILT program, to fit a tilt geometry that in one step agrees with the defocus gradient accross the images.

=== Apply CTF or TTF correction? [ctf_ttf] ===
This allows to define if the image data should be corrected for the Contrast Transfer Function (CTF), assuming a constand defocus over the entire image, or if instead the image data should be corrected for the Tilted CTF (TTF), assuming a tilted sample with spotsplitting of Fourier spots further away from the tilt axis. The latter requires images of higher resolution, and only brings advantages at higher tilt angles (>40deg).

=== Ignore any potential tilt (process with all tilt values as zero [ignore_tilt] ===
Switch, deciding if the tilt angle and tilt axis for this image should be assumed to be "0", in other words, ignored. This parameter only influences the unbending, which will be done without assuming any tilt. For the merging, the determined tilt is still applied.