====== ArithmeticsOnImage ======
Here, a set of arithmetic operations are described, which all use full images as input. If a stack of images is used, the operation is carried out per-image.

===== Processors =====
==== Absolute ====
Calculates and outputs the absolute value for each pixel of every image.

==== Elliptical rotational average ====
|< 100% 30% >|
^ Parameters                            ^ Description     ^
| Cs                                    | Specifies the spherical aberration of the lens system. |
| End angle                             | Defines the ending angle for the averaging procedure in degree. |
| Tension [kV]                          | High tension (in kV) used during image recording in kilo Volts. |
| Mode                                  | Can be set to either 'notional' or 'direct': The notional mode generates an artificial power spectrum either based on information from the header or stated by the user (see parameter 'Use ctf information from image header' below), that is used while averaging. In direct mode, the power spectrum is calculated directly from the input data. |
| Output format                         | Defines the desired output format. |
| Pixel size                            | Defines the pixel size of the input power spectra. |
| Start angle                           | Defines the starting angle for the averaging procedure in degree. |
| Use ctf information from image header | If the image header contains the necessary information (astigmMag, astigmDir, defocus, amplitudeContrastRatio and bfactor) to calculate a power spectrum, this parameter can be set to 'yes'. Otherwise, 'no' must be selected and to specify the information manually. |
| -> Astigmatism direction              | Specifies the magnitude of the astigmatism used during the computation of the artificial CTF power spectrum. |
| -> Astigmatism magnitude              | Specifies the direction of the astigmatism used during the computation of the artificial CTF power spectrum. |
| -> Defocus                            | Specifies the defocus value used during the computation of the artificial CTF power spectrum. |

==== Logarithm ====
Calculates the logarithms naturals of the absolute pixel values plus 1 of every image and writes this to the output images.

==== Rotational average ====
Calculates an rotational average of an image.

|< 100% 30% >|
^ Parameters                 ^ Description     ^
| Output dimension  | Specify, whether the output shall be a center-point symmetric 2D image, or a 1D line. |

==== Square ====
Squares each pixel value in every image and writes the result into the output image.

==== Square root ====
Calculates the square root of every pixel value of every image and writs it into the output images.