Revision as of 02:52, 19 May 2020 by Vincent (talk | contribs) (Commands history: fitseq)

This page contains a list of commands available in the latest version of Siril. The command line is not widely used and rarely tested in its entirety and may not be considered stable yet, 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.


Siril has a command line in its graphical user interface and an ability to run scripts that are a list of commands. Most 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:


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 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.

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 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 stretch

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



Returns the background level of the image loaded in memory.



Returns the background noise level.


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/'



Return the coordinates of the center of gravity of the image.



Clears the graphical output logs



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



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


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 filename

Same function that COSME but applying to RAW CFA images.


convertraw basename [-debayer] [-start=index]

Convert DSLR RAW files into Siril's FITS images. The basename argument is the base name of the new sequence. The debayer option applies demosaicing to images while \"-start=index\" sets the starting index parameter.


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 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



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.



Quits the application.


extract NbPlane

Extracts NbPlane Planes of Wavelet domain.



Extracts Ha signal from a CFA image. The output file name starts with the prefix "Ha_".



Extracts Ha and OIII signals from a CFA image. The output file name start with the prefix "Ha_" and "OIII_".


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 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 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 value x y width height

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


fill2 value x y width height

Same command than 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 cold_sigma hot_sigma

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


find_cosme_cfa cold_sigma hot_sigma

Same command than FIND_COSME but for monochromatic CFA images.


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.



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.


fmedian ksize modulation

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


fmul scalar

Multiplies the loaded image by the scalar given in argument.


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.


gauss sigma

Performs a Gaussian filter with the given sigma.



The function equalizes the mean intensity of RGB layers in a CFA images.



Gives the available commands.


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 filename

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


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 filename

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


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 reference low high

Computes a linear function between a reference image and a target. 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.


load filename
load filename.ext

Loads the image filename; it first attempts to load filename, then 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)



Computes and applies a logarithmic scale to the current image.



Lists files and directories in the working directory.



Rotates the image around a vertical axis.



Rotates the image around an horizontal axis.


mtf low midtone high

Applies midtone transfer function to the current loaded image.



Shows the negative view of the current image.


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 level

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


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 sequencename [-bias=filename] [-dark=filename] [-flat=filename] [-cfa] [-debayer] [-flip] [-equalize_cfa] [-opt] [-prefix=]

Preprocesses the sequence "sequencename" using bias, dark and flat given in argument. It is possible to specify if images are CFA for cosmetic correction purposes with the option "-cfa" and also to demosaic images at the end of the process with "-debayer". The "-flip" option tells to Siril to read image from up to bottom for demosaicing operation and the "-equalize_cfa" option equalizes the mean intensity of RGB layers of the CFA flat master. It is also possible to optimize the dark subtraction with "-opt". The output sequence name starts with the prefix \"pp_\" unless otherwise specified with option "-prefix=".

Note that only hot pixels are corrected in cosmetic correction process



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 sequence [-norot] [-drizzle] [-prefix=]

Performs geometric transforms on images of the sequence given in argument so that they may be superimposed on the reference image. The output sequence name will start with the prefix "r_" unless otherwise specified with \"-prefix=\" option. Using stars for registration, this algorithm only works with deepsky images. The registration is done on the green layer for RGB images. It may work with CFA (not demosaiced) images, but because of luminance factors between each filter and the star colours, it will not be precise and therefore not recommended.

The option "-norot" performs a translation only registration with no new sequence built. 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.


resample factor

Resamples image with a factor "factor".


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 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")


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 degree

Rotates the image of an angle of degree value.



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


satu coeff

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


save filename

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


savebmp filename

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


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 filename

Saves current image as a PNG file.


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 :


savetif filename

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


savetif8 filename

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


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.



seqcrop [_prefix=]

Crops the loaded sequence. The output sequence name starts with the prefix "cropped_" unless otherwise specified with "-prefix=" option.


seqextract_Ha seqname

Same command than [[#extract_Ha|EXTRACT_HA] but for the sequence "seqname". The output sequence name starts with the prefix "Ha_" unless otherwise specified with option "-prefix=".


seqextract_HaOIII seqname

Same command than EXTRACT_HAOIII but for the sequence "seqname". The output sequence name start with the prefix "Ha_" and "OIII_".


seqfind_cosme cold_sigma hot_sigma [-prefix=]

Same command than FIND_COSME but for the loaded sequence. The output sequence name starts with the prefix "cc_" unless otherwise specified with "-prefix=" option.


seqfind_cosme_cfa cold_sigma hot_sigma [-prefix=]

Same command than FIND_COSME_CFA but for the loaded sequence. The output sequence name starts with the prefix "cc_" unless otherwise specified with "-prefix=" option.


seqmtf seqname low midtone high [-prefix=]

Same command than MTF but for the sequence seqname. The output sequence name starts with the prefix "mtf_" unless otherwise specified with "-prefix=" option.



Same command than PSF but works for sequences. Results are dumped in the console in a form that can be used to produce brightness variation curves.


seqsplit_cfa seqname [-prefix=]

Same command that SPLIT_CFA but for the sequence sequencename. The output sequence name starts with the prefix "CFA_" unless otherwise specified with "-prefix=" option.


seqsubsky seqname degree [-prefix=]

Same command that SUBSKY but for the sequence sequencename. The output sequence name starts with the prefix "bkg_" unless otherwise specified with "-prefix=" option.


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.


 setext extension

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


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 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 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 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.


split r g b

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



Splits the CFA image into four distinct files (one for each channel) and save them in files.


 stack seqfilename
 stack seqfilename { sum | min | max } [filtering] [-output_norm] [-out=filename]
 stack seqfilename { med | median } [-nonorm, norm=] [-filter-incl[uded]] [-out=filename]
 stack seqfilename { rej | mean } sigma_low sigma_high [-nonorm, norm=] [filtering] [-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, and rej or mean that requires the use of additional arguments sigma low and high used for the Winsorized sigma clipping rejection algorithm (cannot be changed from here). If no argument other than the sequence name is provided, sum stacking without filtering is assumed.

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

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.



Returns global statistic of the current image. If a selection is made, the command returns global statistic within the selection.


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. A synthetic image is then created and subtracted from the original one.

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.


unselect from to

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



Reset the magnitude calibration to 0. See SETMAG.



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


unsharp sigma multi

Applies to the working image an unsharp mask with sigma sigma and coefficient multi.


visu low high

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


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 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.