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SIPS version 3.24
 Continuously increasing number of SIPS users ensures a steady flow of feedback. We of course try to sort out which of the proposed new functions would be most useful and at the same time appreciated by most users, and implement these features in every new SIPS version. Check what's new in SIPS v3.24 — some of the newly added functions could help you when observing of processing of acquired images.

Main camera (Imager) tool window

Maybe the single most important new feature of the SIPS v3.24 concerns the main imaging camera control. The layout of controls in the Exposure tab was rearranged to save space for the new option, allowing to repeatedly capture images up to defined date/time (that means the number of images is unknown in forward, and only the observing run end time is known). Also the option to repeat images forever (more precisely until they are stopped by the user either by the Stop Exposure button of by un-checking the Forever option) moved to stand-alone check box.

The saved space from removing of unnecessary text-boxes containing only single GUI control, was also used to move Preflash options back from modal dialog box to the Exposure tab, which resulted into simpler Preflash settings.

New Exposure tab of the v3.24 Imager tool (left), layouts of the v3.15 (center) and v3.11 (right) are shown for comparison


Ending date and time is always entered in local time, valid on the particular computer.

SIPS allows to control main camera exposures not only from the Exposure tab, but also from the Series tab, where rather complex repeated sequences and sub-sequences of various image types (light, flat, dark) with various binnings and various filters can be preprogrammed. The ability to repeat either particular image exposure of whole sub-sequence of images until defined date/time was added also to series description.

Image acquisition of whole sub-series can be repeated either for defined number of iterations or until specified date/time

Image acquisition of whole sub-series can be repeated either for defined number of iterations or until specified date/time


The previous SIPS Series allowed only for predefined number of repeats, but also included the possibility to define period, with which the exposure will be acquired. Period made of course sense if it was longer than the exposure time + overhead (download time, image save time, sensor clear time, possible inter-image guiding time, ...). Otherwise the exposures were repeated as fast as possible, which was typically the case when the Period was left at default value 1 second.

But leaving the whole observing setup idle, waiting for period to expire, brings no sense, because image cadence is valuable. Higher cadence captures faster phenomena and allows for higher measurement precision etc. So, the Period was removed from the Series description as an unnecessary feature.

SIPS configuration files handling

SIPS allows setting of rather great number of parameters (currently over five hundreds), from position and open/close status of individual tool window up astrometry catalogs and field curvature correction parameters etc. SIPS saves all these parameters into sips.ini configuration file, located at the {SystemDisk}:\Users\{UserName}\AppData\Roaming\SIPS folder. So, the configuration is stored independently for every user.

But sometimes even single user may need different configurations, for instance if multiple SIPS instances are launched to control multiple observing setups (telescope mount, imaging and guiding cameras, domes, ...). In such cases the SIPS reads configuration of the last recently closed SIPS instance, as the last closed SIPS overwrites the sips.ini file, previously saved by previous instances. If another SIPS has to use different camera, the only choice was to manually set camera and mount driver etc.

New SIPS version 3.24 accepts command-line parameters, which allows the SIPS instance to use up to ten different configuration files. Also, other command line switches allow SIPS not to use configuration upon launch (run with all parameters runt set at default values), and also not to save configuration upon program exit:

  • /config:N — use "sipsN.ini" instead of default "sips.ini" (N is a number 0 to 9)

  • /clean — do not read "sips.ini" configuration file (clean start)

  • /volatile — do not save configuration to the "sips.ini" file upon exit

Running SIPS with the /? command line parameter shows all available command-line options

Running SIPS with the /? command line parameter shows all available command-line options

RAW file import

SIPS natively works with standard FITS file format. Other image formats (both 8-bits and 16-bits per pixel) are supported only for image export. Version 3.24 allows for importing of the raw image in the form of pixel matrix without any header.


The “raw format” is often used by still camera manufacturers to denote image format containing pixel values read directly from the camera sensor, but without actually reconstructed colors from Bayer color mask and often with higher dynamic range than 8-bits per color per pixel, used by e.g. JPEG format. Such images are then processed on the PC, after they are download from the camera.

Unfortunately the actual format of stored data in “raw” files is proprietary (different camera manufacturers use different formats) and often even single company introduces more, mutually incompatible “raw” formats over time. What's more, such formats are often not documented, particular camera manufacturer does not allow other companies to use it but through supplied libraries etc.

The SIPS “Import RAW” function does not concern above mentioned formats, but only pure data matrices without any header stored in files.

Import RAW image dialog box

Import RAW image dialog box

As the image header is missing, number of parameters have to be defined so the SIPS understands how to interpret data file. First, it is necessary to define matrix width and depth (height). Then it is necessary to define the data format of each pixel — SIPS allows selection from 8, 16 and 32-bit signed and unsigned integers and also 32-bit floating-point numbers. The last option is byte order of individual pixels.


As the expected data type is raw matrix of pixels, the size of imported file must equal to defined width multiplied by depth and byte size of each pixel. The Import dialog box shows the calculated expected number of bytes and also the actual size of the selected file. Until these two number are equal, SIPS does not allow proceed with import.

Handling of large (4k+) zoomed images

Maximum size of Windows USER objects (Windows) as well as GDI (Graphics Device Interface) bitmaps is historically limited to 32767 pixels. This seems large enough even today, as the highest-resolution monitors are far from this dimension. But if you take into account for instance C4-16000 camera, producing 4096 ื 4096 images, and zoom the image 8-times, resulting size is 32768 pixels, 1 pixel more than the above mentioned limit. And new camera with up to 9576 ื 6388 pixels resolution are literally virtually around the corner — images from such cameras exceed the 32767 pixels limit when zoomed only 4-times.


SIPS of course does not allocate the bitmaps that big while zooming images, only the visible portion of the image is actually allocated as displayed bitmap, but the 32767 pixels limit is imposed by using of other internal structures.

The new SIPS v3.24 calculates the maximum zoom value for every image loaded from file or read from camera, depending on image dimensions. So, while maximal available zoom is limited (less than 8-times) for large images such images are always displayed correctly.

Photometry tool

SIPS means Scientific Image Processing System and photometry is a fundamental image data analysis performed by researchers, allowing to learn tremendous amount of information about observed objects. So, significant attention is paid to the enhancements of the SIPS Photometry tool.

Photometry Task

Photometry Task dialog box was redesigned, individual blocks of optional parameters were moved to separate Tabs. This allowed to lower the dialog box height (users with the 768p display laptops experienced problems fitting the dialog box on screen).

Another change is the semantics of the Field Curvature definition within the task — now the explicit defined/not defined states can be selected by check-box. Previous versions used only (possibly empty) path to field curvature description file, which was not enough to properly describe all possible variants.

New block of parameters was added to Photometry task, Match Parameters.

This especially allows independent definition of Maximum number of shipped brightest catalog stars parameter to be defined for every task individually (see SIPS v3.22 description for details).

FWHM calculation and display

New SIPS v3.24 calculates FWHM (Full Width at Half Maximum) of all processed stars. FWHM is calculated in 2D cut of star profile, independently in X a Y axes.

FWHM of selected variable star can be displayed within the Light Curve Pane, independently in X and Y axes. As opposed to Air-Mass, FWHM values have own y-direction axis in the chart.

All parts of the Light Curve Pane can be individually turned on and off, so it is possible to examine FWHM changes through the observing run in detail when the variable star magnitude is turned off.

Adding of FWHM also resulted in slight rearrangements of the chart legends, new SIPS v3.24 shows more information in better structured legend.

Limiting the magnitude for the VSX query

Especially for large field of views, captured by short focal length camera lenses, number of variable stars included in VSX can be really big. Displaying of such stars withing the field of view can make it very confusing. This is why SIPS v3.24 added the possibility to limit the magnitude of stars, read form VSX.

This option of course works only if particular star has the magnitude properly defined in the VSX database.

Searching for new variable stars

SIPS Photometry tool allows searching for variable stars within the field of view from the very beginning. New methods of variability detection were added, beside the basic RMS chart, over time. These methods include Variability Detection Index and also sophisticated Neural Network, trained for light curve shapes of all known variable star types.

But searching for new variable stars in a field of view observed for extended period of time means the majority of stars, showing signs of variability, are already known (contained in the Field Description file). But browsing through all known stars when searching if some still unknown variable star appeared in the field only wastes time. This is why new SIPS 3.24 added the possibility to skip all know stars (this means described in the Field Description file) when mowing to another star in the variability index chart.

While the Next or Previous star in the chart hierarchy is still selected by Down/Right and Up/Left arrows, the new function (Next Unknown or Previous Unknown) are selected by the same keys, but when holding the Shift key.

SIPS is a freeware and can be downloaded from the Download section of this web site.

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