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Revision as of 16:52, 18 March 2022 by Vincent (talk | contribs) (→‎gauss: more details)

This page contains a list of commands available in Siril 1.0.0.

Commands are often added or modified, this means that the version of Siril you are using may not be the same as the version documented here.

# Introduction

Siril has a command line in its graphical user interface and an ability to run scripts that are a list of commands, either from the graphical user interface or from the command line interface. Some commands have an effect on the loaded image or sequence and allow them to be processed in some way without user intervention. With 0.9.9, we introduced commands that helped automating the processing of a sequence, like register and stack. They work on sequences that are not loaded.

The <SPACE> character is the delimiter between arguments. If you need to have spaces inside the arguments, you can use the quote or double quote, just like in a shell.

Commands can be typed in the command line at the bottom of Siril's main window. Another way is to put commands in a file and execute it as a script. To execute the file, use the @ token of the command line like so:

    @file_name

# Command stream (pipe)

Starting with 0.9.10, a new mode has been introduced in which commands can be sent through a named pipe and logs and status can be obtained through another. The mode is activated using the `-p` command line argument.

The protocol is quite simple: Siril receives commands and outputs some updates. Only commands that are marked as scriptable can be used with this system. Whenever the command inputs pipe is closed or the `cancel` command is given, the running command is stopped as if the stop button was clicked on in the GUI. The pipes are named `siril_command.in` and `siril_command.out` and are available in /tmp on Unix-based systems.

Outputs of siril on the pipe is a stream of one line text and formatted as follows:

- `log:` followed by a log message
- `status: verb [subject]`, where verb can be either of `starting`, `success`, `error` or `exit` (exit message is not yet implemented). The subject is the current command name, except for exit that indicates that siril suffered a fatal error and has to exit.
- `progress: value%` is the equivalent of the progress bar, it sends percents periodically, and sometimes 0% at the end of a processing as an idle information.

# Commands history

These lists help you see what has changed in the last version, whether new or modified commands.

- 1.0.0: update of rl, stack, stackall (adding -output_norm and rejection algorithms), preprocess (removing -stretch and -flip and adding -fix_xtrans) and convertraw (adding -start=index, -out=directory and -fitseq -ser). Also, a `-prefix=` option has been added to the sequence commands that build a new sequence.
  New commands subsky, seqsubsky, neg, mtf, seqmtf, linear_match, extract_Ha, extract_HaOIII, seqextract_Ha, set16bits, set32bits, setcompress, seqextract_HaOIII, link, convert, reloadscripts, fix_xtrans, requires, merge, seqstat, setref, seqextract_Green, extract_Green, tilt, boxselect
- 0.9.12: split_cfa, seqsplit_cfa
- 0.9.11: stack, stackall, setmem
- 0.9.10: setfindstar, grey_flat, asinh, rgradient
- 0.9.9: convertraw, preprocess, register, stack, close, clear, setext, @
- 0.9.8: savepng, stackall

# Siril command line functions reference

This is the list of commands available in the development version of Siril. Check the list above, some may not be available in your version.

## addmax

    addmax filename

addmax compute a new image IMG with IMG_1 and IMG_2. The pixel of IMG_1 is replaced by the pixel at the same coordinates of IMG_2 if the intensity of 2 is greater than 1. Do not forget to save the result.

## asinh

    asinh stretch

asinh command stretches the image for show faint objects, while simultaneously, preserve the structure of bright objects of the field.

## bg

    bg

Returns the background level of the image loaded in memory.

## bgnoise

    bgnoise

Returns the background noise level.

## boxselect

    boxselect [x y width height]

Make a selection with the arguments `x`, `y`, `width` and `height`, with `x` and `y` being the coordinates of the top left corner of the selection from the top left corner of the image, and `width` and `height`, the size of the selection.

If no argument is passed and a selection is active, it writes the corresponding `x`, `y`, `width` and `height` in the console.

## cd

    cd directory

Set the new current working directory. `directory` can contain the ~ token, expanded as the home directory, directories with spaces in the name can be protected using single or double quotes. Examples:

- `cd ~/M42`
- `cd '../OIII 2x2/'`

## cdg

    cdg

Return the coordinates of the center of gravity of the image. Only pixels with values above 15.7% of max ADU and having four neighbors filling the same condition are used to compute it, and it is computed only if there are at least 50 of them.

## clahe

    clahe cliplimit tileSize

Equalizes the histogram of an image using Contrast Limited Adaptive Histogram Equalization

## clear

    clear

Clears the graphical output logs

## clearstar

    clearstar

Clear all the stars saved in memory and displayed on the screen.

## close

    close

Properly closes the opened image and the opened sequence, if any.

## convert

    convert basename [-debayer] [-start=index] [-out=directory] [-fitseq] [-ser]

Convert all images of the current working directory that are in a supported format into Siril's sequence of FITS images (several files) or a FITS sequence (single file) if `-fitseq` is provided or a SER sequence (single file) if `-ser` is provided. The argument `basename` is the base name of the new sequence, numbers and the extension will be put behind it.

For FITS images, Siril will try to make a symbolic link; if not possible, files will be copied. The option `-debayer` demosaics the input CFA images, in this case new RGB files are created.

`-start=index` sets the starting index parameter for the converted images (not used with `-fitseq` or `-ser`) useful to continue an existing sequence (make sure you remove the target .seq if it exists in that case, or that you check force .seq recomputation when searching sequences.

The `-out=` option changes the output directory to the provided argument.

## convertraw

    convertraw basename [-debayer] [-start=index] [-out=directory] [-fitseq]

Convert DSLR RAW files into Siril's FITS images or a FITS sequence (single file / FITS cube) if `-fitseq` is provided or a SER sequence (single file) if `-ser` is provided. The basename argument is the base name of the new sequence. The `debayer` option applies demosaicing to images, `-start=index` sets the starting index parameter and `-out=directory` provides a directory for output files inseead of the CWD. For more information on arguments see convert.

## cosme

    cosme filename

Apply the local mean to a set of pixels on the in-memory image (cosmetic correction). The coordinate of this pixels are in an ASCII file [list file]. COSME is adapted to correct residual hot and cold pixels after preprocessing.
The line `P x y type` will fix the pixel at coordinates `(x, y)` `type` is an optional character (`C` or `H`) specifying to Siril if the current pixel is cold or hot. This line is created by the command `find_hot` but you also can add some lines manually.
The line `C x 0 type` will fix the bad column at coordinates `x`.
The line `L y 0 type` will fix the bad line at coordinates `y`.

## cosme_cfa

    cosme_cfa filename

Same function as COSME but applying to RAW CFA images.

## crop

    crop [x, y, width, height]

It can be used with the GUI: if a selection has been made with the mouse, calling the crop command without arguments crops it on this selection. Otherwise, or in scripts, arguments have to be given, with x and y being the coordinates of the top left corner, and width and height the size of the selection.

## ddp

    ddp level coef sigma

Performs a DDP (digital development processing) as described first by Kunihiko Okano. This implementation is the one described in IRIS. It combines a linear distribution on low levels (below level) and a non-linear on high levels. It uses a Gaussian filter of sigma sigma multiplies the resulting image by coef. The typical values for sigma are included between 0.7 and 2

## entropy

    entropy

Computes the entropy of the opened image on the displayed layer, only in the selected area if one has been selected or in the whole image else. The entropy is one way of measuring the noise or the details in an image.

## exit

    exit

Quits the application.

## extract

    extract NbPlane

Extracts NbPlane planes of Wavelet domain. For color extraction, see split.

## extract_Green

    extract_Green

Extracts green signal from the currently loaded CFA image. It reads the Bayer matrix information from the image or the preferences and exports only the averaged green filter data as a new half-sized FITS file. The output file name starts with the prefix "Green_".

See SEQEXTRACT_GREEN for the same operation for sequences.

## extract_Ha

    extract_Ha

Extracts H-alpha signal from the currently loaded CFA image. It reads the Bayer matrix information from the image or the preferences and exports only the red filter data as a new half-sized FITS file. The output file name starts with the prefix "Ha_".

See SEQEXTRACT_HA for the same operation for sequences.

## extract_HaOIII

    extract_HaOIII

Extracts H-alpha and O-III signals from the currently loaded CFA image. It reads the Bayer matrix information from the image or the preferences and exports only the red filter data for H-alpha and an average of the three others as a new half-sized FITS files. The output file name start with the prefixes "Ha_" and "OIII_".

See SEQEXTRACT_HAOII for the same operation for sequences.

## fdiv

    fdiv filename scalar

Divides the image in memory by the image given in argument. The resulting image is multiplied by the value of the scalar argument. Please check that the image is in the working directory.

See also idiv.

## fftd

    fftd modulus phase

Applies a Fast Fourier Transform to the image loaded in memory. Modulus and phase given in argument are saved in FITS files.

## ffti

    ffti modulus phase

This function is used to retrieve corrected image applying an inverse transformation. The modulus and phase used are the files given in argument.

## fill

    fill value x y width height

Fills the whole current image (or selection) with pixels having the value intensity.

## fill2

    fill2 value x y width height

Same command as FILL but this is a symmetric fill of a region defined by the mouse. Used to process an image in the Fourier (FFT) domain.

## find_cosme

    find_cosme cold_sigma hot_sigma

This command applies an automatic detection of cold and hot pixels following the threshold written in arguments.

## find_cosme_cfa

    find_cosme_cfa cold_sigma hot_sigma

Same command as FIND_COSME but for monochromatic CFA images.

## find_hot

    find_hot filename cold_sigma hot_sigma

The command provides a list file `filename` (format text) in the working directory which contains the coordinates of the pixels which have an intensity `hot_sigma` times higher and `cold_sigma` lower than standard deviation. We generally use this command on a master-dark file.

## findstar

    findstar

Detects stars having a level greater than a threshold computed by Siril. The algorithm is based on the publication of Mighell, K. J. 1999, in ASP Conf. Ser., Vol. 172, Astronomical Data Analysis Software and Systems VIII, eds. D. M. Mehringer, R. L. Plante, & D. A. Roberts (San Francisco: ASP), 317.

After that, a PSF is applied and Siril rejects all detected structures that don't fulfill a set of prescribed detection criteria. Finaly, a circle is drawn around detected stars. See also the command CLEARSTAR.

## fix_xtrans

     fix_xtrans

Fixes the Fujifilm X-Trans Auto Focus pixels. Indeed, because of the phase detection auto focus system, the photosites used for auto focus get a little less light than the surrounding photosites. The camera compensates for this and increases the values from these specific photosites giving a visible square in the middle of the dark/bias frames.

## fixbanding

    fixbanding amount sigma

Try to remove the canon banding. Argument `amount` define the amouont of correction. Sigma defines a protection level of the algorithm, higher sigma gives higher protection.

## fmedian

    fmedian ksize modulation

Performs a median filter of size ksize [math]\displaystyle{ \times }[/math]ksize (ksize MUST be odd) to the original image with a modulation parameter modulation. The output pixel is computed as : out [math]\displaystyle{ = }[/math]mod [math]\displaystyle{ \times\ m + (1- }[/math]mod[math]\displaystyle{ ) \times }[/math]in, where m is the median-filtered pixel value. A modulation's value of 1 will apply no modulation.

## fmul

    fmul scalar

Multiplies the loaded image by the scalar given in argument.

## gauss

    gauss sigma

Applies to the working image a Gaussian blur with parameter `sigma`.

See also UNSHARP, the same with a blending parameter.

## grey_flat

    grey_flat

The function equalizes the mean intensity of RGB layers in a CFA images. This is the same process used on flats during preprocessing when the option equalize CFA is used.

## help

    help

Gives the available commands.

## histo

    histo layer

Calculates the histogram of the image layer in memory and produces file histo_[layer name].dat in the working directory.

layer = 0, 1 or 2 with 0=red, 1=green and 2=blue.

## iadd

    iadd filename

Adds the image in memory to the image designed in argument. Please check that the image is in the working directory.

## idiv

    idiv filename

Divides the image in memory by the image given in argument. Please check that the image is in the working directory. See also fdiv.

## imul

    imul filename

Multiplies the image in memory by the image given in argument. Please check that the image is in the working directory.

## isub

    isub filename

Substracts the image in memory by the image given in argument. Please check that the image is in the working directory.

## linear_match

    linear_match reference low high

Computes a linear function between a reference image and a target image already loaded in memory. The function is then applied to the target image to match it to the reference one. The algorithm will ignore all reference pixels whose values are outside of the [low, high] range. The target image is not saved after the call, see the save command.

## link

     link basename [-start=index] [-out=directory]

Create a new sequence from all FITS images found in the current working directory by linking them to a new name starting with the basename given in argument. If no symbolic link could be created, files are copied. The `-out=` option changes the output directory to the provided argument.

## load

    load filename
    load filename.ext

Loads the image filename; it first attempts to load filename, then filename.fit and finally filename.fits and after, all supported format, aborting if none of these are found. These scheme is applicable to every Siril command implying reading files. Fits headers MIPS-HI and MIPS-LO are read and their values given to the current viewing levels. Writing a known extension at the end of filename will load the image filename.ext: this is used when numerous files have the same name but not the same extension.

Extensions supported are :

- *.fit, *.fits, *.fts
- *.bmp / *.jpg, *.jpeg / *.png / *.tif, *.tiff
- *.ppm, *.pgm
- *.pic (IRIS file)

## log

    log

Computes and applies a logarithmic scale to the current image, using the following formula: log(1 - (value - min) / (max - min)), with min and max being the minimum and maximum pixel value for the channel.

## ls

    ls

Lists files and directories in the working directory.

## merge

    merge seq1 seq2 [... seqn] newseq

Merges several sequences of the same type (FITS images, FITS sequence or SER) and same image properties into a new sequence with base name `newseq` created in the current working directory, with the same type. The input sequences can be in different directories, can specified either in absolute or relative path, with the exact .seq name or with only the base name with or without the trailing '_'.

## mirrorx

    mirrorx

Rotates the image around a vertical axis.

## mirrory

    mirrory

Rotates the image around an horizontal axis.

## mtf

    mtf low midtone high

Applies midtone transfer function to the current loaded image. Three parameters are needed, `low`, `midtones` and `high` where midtones balance parameter defines a nonlinear histogram stretch in the [0,1] range

## neg

    neg

Shows the negative view of the current image.

## new

    new width height nb_layers

Creates a new image filled with zeros with a size of `width x height`. The image is in 16-bit format, and it contains `nb_layers` layers, `nb_layers` being 1 or 3. It is not saved, but displayed and can be saved afterwards.

## nozero

    nozero level

Replaces null values by level values. Useful before an idiv or fdiv operation.

## offset

    offset value

Adds the constant value to the current image. This constant can take a negative value. As Siril uses unsigned fit files, if the intensity of the pixel become negative its value is replaced by 0 and by 65535 (for a 16-bit file) if the pixel intensity overflows. To check the minimum and maximum intensities values, click on the Auto level button and note the low and high threshold.

## preprocess

    preprocess sequencename [-bias=filename|value] [-dark=filename] [-flat=filename] [-cfa] [-debayer] [-fix_xtrans] [-equalize_cfa] [-opt] [-prefix=] [-fitseq]

Preprocesses (calibrates) the sequence `sequencename` using any of bias, dark and flat masters given in argument.

The bias master file can be replaced by an integer value or an expression that uses the `OFFSET` entry from the FITS header, in the form `=2048` or `=64*$OFFSET`. See the tutorial on synthetic bias for more information.

If dark is provided, cosmetic correction is enabled too, but only for hot pixels.

Three options apply to color images (in CFA format): `-cfa` for cosmetic correction purposes, `-debayer` to demosaic them before saving and `-equalize_cfa` to equalize the mean intensity of the three R, G and B layers of the CFA flat master to avoid giving a tint to the calibrated image.

The `-fix_xtrans` option is dedicated to X-Trans files by applying a correction on dark and bias images to remove an ugly square pattern caused by autofocus.

It is also possible to optimize (adjust its level to match the offset of the image) the dark subtraction with `-opt`, possible only if both bias and dark masters are provided.

The output sequence name starts with the prefix "pp_" unless otherwise specified with option `-prefix=`. If `-fitseq` is provided, the output sequence will be a FITS sequence (single file).

## psf

    psf

Performs a PSF (Point Spread Function) on the selected star.

Make a selection around a star and call the command PSF. It will give you:

- The centroid coordinates (x0 and y0) in pixel units, which is the position of the center of symmetry of the fitted PSF.
- The FWHM on the X and Y axis.
- The rotation angle of the X axis with respect to the centroid coordinates.
- The average local background.
- The maximal intensity of the star: this is the peak value of the fitted function, located at the centroid coordinates x0 and y0.
- The relative magnitude of the star.
- The RMSE. This is an estimate of fitting quality. The smaller the RMSE is, the better the function is fitted.

To be relevant, the selection MUST be done on a non-saturated star.

## register

    register sequence [-norot] [-drizzle] [-prefix=] [-minpairs=] [-transf=]

Performs geometric transforms on images of the sequence given in argument so that they may be superimposed on the reference image. Using stars for registration, this algorithm only works with deepsky images. The registration is done on the green layer for RGB images.

The output sequence name starts with the prefix `r_` unless otherwise specified with `-prefix=` option. The option `-drizzle` activates the sub-pixel stacking, either by up-scaling by 2 the images created in the rotated sequence or by setting a flag that will proceed to the up-scaling during stacking if `-norot` is passed. The option `-transf=` specifies the use of either `shift`, `affine` or `homography` transformations respectively, homography being the default unless `-norot` is passed, which uses shift as default. The option `-minpairs=` will specify the minimum number of star pairs a frame must have with the reference frame, otherwise the frame will be dropped.")

## reloadscripts

    reloadscripts

Rescans the scripts folders and updates scripts menu.

## requires

    requires x.y.z

This function returns an error if the version of Siril is older than the one passed in argument.

## resample

    resample factor

Resamples image with a factor `factor`. This is generally used to resize images, a factor of 0.5 divides size by 2.

In the graphical user interface, we can see that several interpolation algorithms are proposed. Here, Pixel Area Relation is used and cannot be changed.

## rgradient

    rgradient xc yc dR dalpha

Creates two images, with a radial shift (`dR` in pixels) and a rotational shift (`dalpha` in degrees) with respect to the point (`xc`, `yc`). Between these two images, the shifts have the same amplitude, but an opposite sign. The two images are then added to create the final image. This process is also called Larson Sekanina filter.

## rl

    rl threshold sigma corner_radius_boost iterations

Restores an image using the Richardson-Lucy method. Threshold generates an internal mask based on microcontrast in the image which then is used to blend the deconvoluted with the convoluted image. Sigma is the size of the kernel to be applied, while corner_radius_boost is a value which is added to Gaussian sigma for the tiles in the corners of an image. Iterations is the number of iterations to be performed.

Valid values are 0.4 to 2.0 for sigma and -0.5 to 0.5 for corner_radius_boost.

## rmgreen

    rmgreen type

rmgreen is a chromatic noise reduction filter. It removes green noise in the current image. This filter is based on PixInsight's SCNR Average Neutral algorithm and it is the same filter used by HLVG plugin in Photoshop. In command line, the lightness is always preserved. For image processing without L* preservation use the graphical tool box and uncheck the corresponding button.

Type=1 stands for Average Neutral Protection, while type=2 stands for Maximum Neutral Protection.

## rotate

    rotate degree

Rotates the image of an angle of degree value.

## rotatepi

    rotatepi

Rotates the image of an angle of 180° around its center. This is equivalent to the command `rotate 180` or `rotate -180`.

## satu

    satu coeff

Enhances the global saturation of the image. Try iteratively to obtain best results. For example: satu 0.1

## save

    save filename

Saves current image to filename.fit. Fits headers MIPS-HI and MIPS-LO are added with values corresponding to the current viewing levels.

## savebmp

    savebmp filename

Saves current image under the form of a bitmap file with 8bits per channel: filename.bmp (BMP 24 bits).

## savejpg

    savejpg filename [quality]

Saves current image into a JPG file. You have the possibility to adjust the quality of the compression. A value 100 for quality parameter offers best fidelity while a low value increases the compression ratio. If no value is specified, it holds a value of 100. This command is very usefull to share an image in the jpeg format on the forums for example.

## savepng

    savepng filename

Saves current image as a PNG file, with 16 bits per channel if the loaded image is 16 or 32 bits, and 8 bits per channel if the loaded image is 8 bits.

## savepnm

    savepnm filename

Saves current image under the form of a Netpbm file format with 16bits per channel. The extension of the output will be filename.ppm for RGB image and filename.pgm for gray-level image. More details about the Netpbm format at : http://en.wikipedia.org/wiki/Netpbm_format.

## savetif

    savetif filename

Saves current image under the form of a uncompressed TIFF file with 16bits per channel.

## savetif8

    savetif8 filename

Same command as SAVE_TIF but the output file is saved in 32bits per channel.

## savetif8

    savetif8 filename

Same command as SAVE_TIF but the output file is saved in 8bits per channel.

## select

    select from to

This command allows easy mass selection of images in the loaded sequence (from - to, to included). Examples:

    select 0 0

selects the first.

    select 1000 1200

selects 201 images starting from number 1000

The second number can be greater than the number of images to just go up to the end.

See UNSELECT.

## seqcosme

    seqcosme seqname [filename].lst [-prefix=]

Same command as COSME but for the the sequence `sequencename`.

The output sequence name starts with the prefix "cosme_" unless otherwise specified with option `-prefix=`. Only selected images in the sequence are processed.

## seqcosme_cfa

    seqcosme_cfa seqname [filename].lst [-prefix=]

Same command as COSME_CFA but for the the sequence `sequencename`.

The output sequence name starts with the prefix "cosme_" unless otherwise specified with option `-prefix=`. Only selected images in the sequence are processed.

## seqcrop

    seqcrop seqname x y width height [-prefix=]

Crops the sequence given in the `seqname` argument. The output sequence name starts with the prefix "cropped_" unless otherwise specified with `-prefix=` option. Only selected images in the sequence are processed.

## seqextract_Green

    seqextract_Green seqname [-prefix=]

Same command as EXTRACT_GREEN but for the sequence `seqname`. The output sequence name starts with the prefix "Green_" unless otherwise specified with option `-prefix=`. Only selected images in the sequence are processed.

## seqextract_Ha

    seqextract_Ha seqname [-prefix=]

Same command as EXTRACT_HA but for the sequence `seqname`. The output sequence name starts with the prefix "Ha_" unless otherwise specified with option `-prefix=`. Only selected images in the sequence are processed.

## seqextract_HaOIII

    seqextract_HaOIII seqname

Same command as EXTRACT_HAOIII but for the sequence `seqname`. The output sequences names start with the prefixes "Ha_" and "OIII_". Only selected images in the sequence are processed.

## seqfind_cosme

    seqfind_cosme cold_sigma hot_sigma [-prefix=]

Same command as FIND_COSME but for the loaded sequence. The output sequence name starts with the prefix "cc_" unless otherwise specified with `-prefix=` option. Only selected images in the sequence are processed.

## seqfind_cosme_cfa

    seqfind_cosme_cfa cold_sigma hot_sigma [-prefix=]

Same command as FIND_COSME_CFA but for the loaded sequence. The output sequence name starts with the prefix "cc_" unless otherwise specified with `-prefix=` option. Only selected images in the sequence are processed.

## seqmtf

    seqmtf seqname low midtone high [-prefix=]

Same command as MTF but for the sequence seqname. The output sequence name starts with the prefix "mtf_" unless otherwise specified with `-prefix=` option. Only selected images in the sequence are processed.

## seqpsf

    seqpsf

Same command as PSF but works for sequences. This is similar to the one-star registration, except results can be used for photometry analysis rather than aligning images.

This command is what is called internally by the menu that appears on right click in the image, with the PSF for the sequence entry. By default, it will run with parallelisation activated; if registration data already exists for the sequence, it will be used to shift the search window in each image. If there is no registration data and if there is significant shift between images in the sequence, the default settings will fail to find stars in the initial position of the search area.

The follow star option can then be activated by going in the registration tab, selecting the one-star registration and checking the follow star movement box.

Results will be displayed in the Plot tab, from which they can also be exported to a comma-separated values (CSV) file for external analysis.

When creating a light curve, the first star for which seqpsf has been run, marked 'V' in the display, will be considered as the variable star. All others are averaged to create a reference light curve subtracted to the light curve of the variable star.

## seqsplit_cfa

    seqsplit_cfa seqname [-prefix=]

Same command as SPLIT_CFA but for the sequence `seqname`. The output sequence name starts with the prefix "CFA_" unless otherwise specified with `-prefix=` option. Only selected images in the sequence are processed.

Limitation: the sequence always outputs a sequence of FITS files, no matter the type of input sequence.

## seqstat

    seqstat seqname output [option]

Same command as STAT bit for sequence `sequencename`. Only selected images in the sequence are processed. The output is saved in a csv file given in second argument, the meaning of each value is explained in the statistics documentation page. The optional parameter can be `basic` or `main`. `basic` includes mean, median, sigma, bgnoise, min and max. `main` includes `basic` with the addition of avgDev, MAD and the square root of BWMV.

## seqsubsky

    seqsubsky seqname degree [-prefix=]

Same command as SUBSKY but for the sequence `sequencename`. The output sequence name starts with the prefix "bkg_" unless otherwise specified with `-prefix=` option. Only selected images in the sequence are processed.

## set16bits

    set16bits

Forbid images to be saved with 32 bits per channel on processing, use 16 instead.

## set32bits

    set32bits

Allow images to be saved with 32 bits per channel on processing.

## setcompress

    setcompress 0/1 [-type=] [q] [hscale_factor]

Defines if images are compressed or not: 0 means no compression. If compression is enabled, the type must be explicitly written in the option `-type=` (`rice`, `gzip1`, `gzip2` and `hcompress`). Associated to the compression, the quantization value must follow [0, 256] and in the case of `hcompress`, the hcompress scale factor [0, 256] as well. For example, `setcompress 1 -type=rice 16` set the rice compression with a quantization of 16.

## setcpu

    setcpu number

Defines the number of processing threads used for calculation. Can be as high as the number of virtual threads existing on the system, which is the number of CPU cores or twice this number if hyper-threading (Intel HT) is available. The default value is the maximum number of threads available, so this should mostly be used to limit processing power. See also SETMEM.

Warning: this command does not persist over siril restarts, contrary to SETMEM which is saved in settings.

## setext

     setext extension

Sets the extension used and recognized by sequences. The argument `extension` can be `fit`, `fts` or `fits`.

## setfindstar

    setfindstar ksigma roundness

Defines thresholds above the noise and star roundness for all subsequent stars detection with FINDSTAR and REGISTER commands of the session. Ksigma must be greater or equal to 0.05 and roundness between 0 and 0.9.

The threshold for star detection is computed as the median of the image (which represents in general the background level) plus `Ksigma` times sigma, sigma being the standard deviation of the image (which is a good indication of the noise amplitude). If you have many stars in your images and a good signal/noise ratio, it may be a good idea to increase this value to speed-up the detection and false positives.

The roundness argument is the minimal ratio of the short axis on the long axis of the star Gaussian fit (see PSF). A value of 1 would keep only perfectly round stars, a value of 0.5, the default, means that stars detected twice as big on an axis as on the other will still be used for registration.

It is recommended to test the values used for a sequence with Siril's GUI, available in the dynamic PSF toolbox from the analysis menu. It may improve registration quality to increase the parameters, but it is also important to be able to detect several tens of stars in each image.

## setmag

    setmag magnitude

Calibrates the magnitude by selecting a star and giving the known apparent magnitude. All PSF computations will return the calibrated apparent magnitude afterwards, instead of an apparent magnitude relative to ADU values. To reset the magnitude constant see UNSETMAG.

## setmagseq

    setmagseq magnitude

This command is only valid after having run seqpsf or its graphical counterpart (select the area around a star and launch the psf analysis for the sequence, it will appear in the graphs). This command has the same goal as setmag but recomputes the reference magnitude for each image of the sequence where the reference star has been found. When running the command, the last star that has been analysed will be considered as the reference star. Displaying the magnitude plot before typing the command makes it easy to understand. To reset the reference star and magnitude offset, see unsetmagseq.

## setmem

    setmem ratio

Sets a new ratio of free memory on memory used for stacking. Value should be between 0 and 1, depending on other activities of the machine. A higher ratio should allow siril to stack faster. Introduced in 0.9.11. See also SETCPU.

## setref

    setref sequencename image

Sets the reference image of the sequence given in first argument.

## split

    split r g b

Splits the currently loaded color image into three distincts files (one for each color) and save them in r g and b FITS files.

## split_cfa

    split_cfa

Splits the currently loaded CFA image into four distinct images (one for each filter of the Bayer matrix) and save them in FITS files. See SEQSPLIT_CFA for the same operation on a sequence.

Not supported for XTRANS sensors.

## stack

     stack seqfilename
     stack seqfilename { sum | min | max } [filtering] [-weighted][-output_norm] [-out=filename]
     stack seqfilename { med | median } [-nonorm, norm=] [-filter-incl[uded]] [-weighted] [-out=filename]
     stack seqfilename { rej | mean } [rejection type] sigma_low sigma_high [-nonorm, norm=] [filtering] [-weighted] [-out=filename]

With `filtering` being some of these in no particular order or number:

     [-filter-fwhm=value[%]] [-filter-wfwhm=value[%]] [-filter-round=value[%]]
     [-filter-quality=value[%]] [-filter-incl[uded]]

Stacks the `seqfilename` sequence, using options.

The allowed types are: `sum`, `max`, `min`, `med` or `median`. The rejection type is one of {p[ercentile] | s[igma] | m[edian] | w[insorized] | l[inear] | g[eneralized] | [m]a[d]} for Percentile, Sigma, Median, Winsorized, Linear-Fit, Generalized Extreme Studentized Deviate Test or k-MAD clipping. If omitted, the default (Winsorized) is used. The `sigma low` and `high` parameters of rejection are mandatory.

See the tooltips in the stacking tab for more information about the stacking methods and rejection types, or see the documentation.

Best images from the sequence can be stacked by using the filtering arguments. The filtering uses registration data, either with a value for the last image to take depending on the type of data used (between 0 and 1 for roundness and quality) or a percentage of best images to keep if the number is followed by a `%` sign. It is also possible to use manually selected images, either previously from the GUI or with the select or unselect commands.

If several filters are added to the command, only images that pass all the filters will be stacked. There is consequently no order. If a filter is badly declared, because it has no registration data or a too low threshold, nothing will be stacked.

Normalization is automatically enabled for median and mean with rejection stacking methods. This can be overridden using the `-nonorm` flag or the `-norm=normalization` option. The allowed normalization are: `add`, `addscale`, `mul` or `mulscale`. For other methods, or with the use of the `-nonorm` flag, normalization is disabled.

`-output_norm` applies a normalization at the end of the stacking to rescale result in the [0, 1] range.

Stacked image for the sequence is created with the name provided in the optional argument `-out`, or with the name of the sequence suffixed "_stacked" and the configured FITS file extension. If a file with this name already exists, it will be overwritten without warning.

Note that this command was added in the 0.9.9 release, the filtering and output naming options were added in the 0.9.11 release and the output_norm in the 1.00.

## stackall

     stackall
     stackall { sum | min | max } [filtering] [-weighted]
     stackall { med | median } [-nonorm, norm=] [-filter-incl[uded]] [-weighted]
     stackall { rej | mean } sigma_low sigma_high [-nonorm, norm=] [-output_norm] [filtering] [-weighted]

With `filtering` being some of these in no particular order or number:

     [-filter-fwhm=value[%]] [-filter-wfwhm=value[%]] [-filter-round=value[%]]
     [-filter-quality=value[%]] [-filter-incl[uded]]

Opens all sequences in the current working directory (CWD) and stacks them with the optionally specified stacking type or with sum stacking. See stack commands for options description.

Stacked images for each sequence are created with the suffix "_stacked" and the configured FITS file extension.

Note that most options for this command were introduced in the 0.9.8 release, the filtering options were introduced in the 0.9.11 release and the `output_norm` option in the 1.0.0 release.

## stat

    stat

Returns global statistics of the current image. The meaning of each value is explained on the statistics documentation page. If a selection is made, the command returns global statistics within the selection. To compute the statistics on a sequence, see SEQSTAT.

## subsky

    subsky degree

Computes the level of the local sky background thanks to a polynomial function of an order `degree` and subtracts it from the image. The other parameters, visible in the graphical user interface, are set automatically to 20 samples per line with a tolerance of 1 and dithering enabled.

## threshlo, threshhi, thresh

These are threshold functions:

- `threshlo 40` replaces values below 40 with 40;
- `threshhi 1000` replaces values above 1000 with 1000;
- `thresh 40 1000` does both.

## tilt

    tilt

Computes the Sensor tilt as the fwhm difference between the best and worst corner truncated mean values. The `clear` option allows to clear the drawing.

## unselect

    unselect from to

Allows easy mass unselection of images in the loaded sequence (from - to). See SELECT.

## unsetmag

    unsetmag

Reset the magnitude calibration to 0. See SETMAG.

## unsetmagseq

    unsetmagseq

Resets the magnitude calibration and reference star for the sequence. See SETMAGSEQ.

## unsharp

    unsharp sigma amount

Applies to the working image an unsharp mask, actually a Gaussian filtered image with parameter `sigma` and a blend with the parameter `amount` used as such: `out = in * (1 + amount) + filtered * (-amount)`.

See also GAUSS, the same without the blending.

## visu

    visu low high

Displays an image with low and high as the low and high threshold.

## wavelet

    wavelet plan_number type

Computes the wavelet transform on `nbr_plan` plans using linear (`type=1`) or bspline (`type=2`) version of the 'a trous' algorithm. The result is stored in a file as a structure containing the planes, ready for weighted reconstruction with WRECONS.

## wrecons

    wrecons c1 c2 ... cn

Reconstructs to current image from the planes previously computed with wavelets and weighted with coefficients `c1, c2, ..., cn` according to the number of planes used for wavelet transform.

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