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[Closed] Astro Pixel Processor 1.069

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Astro Pixel Processor 1.069

Due to some star analysis and registration issues on some particular datasets, i.e.:

  • widefield data
  • data with dense star fields
  • out-of-focus data
  • data with big stars, (Full Width at Half Maximum larger than 10 pixels)


I decided to do extensive work to rebuild the  3) Analyse Stars module to prevent the problems with these datasets AND with the goal to make Star Analysis easier for robust registration of all datasets.

The result is that module 3) Analyse Stars has been greatly simplified  now 😉

Several settings have been made redundant so that should improve user experience significantly.

The following settings have been made redundant:

  • minimum star size area, APP will now automatically detect this from the data, so the user is no longer bothered with this setting 😉
  • clip star profile, this setting enabled control over how many stars were detected and had influence on which parts of star intensity profiles were used to determine the star FWHM value and the star's location in subpixel coordinates (it's centroid). APP will now simply use the top 95 % of each intensity profile for each detected star to determine the star centroid by Intensity Weighted Centroiding (IWC) and FWHM value by regression.
  • filter star profile, star profiles are filtered automatically now in certain cases were they can and should help in improving the star centroid calculations. The result is that registration will have better and more robust precision, i.e. lower registration RMS error. Star profiles are filtered/convoluted with a 3x3 block kernel in the following cases
    • stars that consist of only 8 pixels or less, in these cases, noise in the star profile can have a clear negative effect on the star centroid calculation. Filtering will make the centroid calculation more reliable. This typically has the effect that star centroid calculation can be improved with 0.05-0.10 pixels, which in turn can give a  registration precision increase of 0.05-0.1 pixel
    • if regression of the star profile is difficult, filtering will make the centroid calculation more reliable in these cases as well.
  • out of focus? FWHM > 12 pixels?, this setting has no use anymore, since APP is now able to detect the average star size in the data and will then automatically adjust for star profiles with large FWHM values or for star profiles that are not in focus.


So for star detection and registration, the user will now only need to simply adjust the minimum and maximum #stars targets. The default values of 500-1000 should be fine for normal integrations. For mosaic integrations, these values need to be a bit larger depending on how much stars there will be in the overlapping mosaic panels.


  • Improved, Star Map Image Viewer Mode, the star map will now be shown more clearly and it will load faster, especially in the case of data with lots of stars. The PSF Contour map drawing has been improved as well (For big FWHM values, the old drawing was incorrect) to better show the star shape and size in the data. The star shapes shown in the star map reflect the calculated size and shape of the stars. The area of data that is shown for each star has a radius of 3x it's FWHM value taking into account a star's elliptical/circular shape. Examples shown are courtesy of the NASA Wide-field Infrared Survey Explorer or WISE telescope.
Data used for starMap
starMap min500 max1000
Data And StarMap
Data Crop
Data And StarMap crop
  • FIXED, BACKGROUND NEUTRALIZATION algorithm, a bug was fixed which caused APP to enter a never ending loop which caused APP to stall. The bug manifested itself only on images with particular image dimensions and was described here: . The Calibrate Background and Remove Light Pollution tools always start with a first preview of the data using Background Neutralization. So on certain light frames/integrations, the tools would have entered a never ending loop.
  • FIXED, OpenGL ImageViewer, I have removed the HiDPI or no HiDPI message above the image viewer, because on screens with small resolutions. The text above the image viewer was too long.
  • FIXED, Star Color Calibration, the blackbody and extinction models have a multiplicative 3x3 color calibration matrix and 3 additive sky background correction factors. This is now shown properly in the small console window in the Star Color Calibration tool. Data shown is M51, the Whirlpool galaxy, courtesy of Dutch
StarColorCalibration parameters
StarColorCalibration parameters shown properly
  • IMPROVED, Star Color Calibration, since the star analysis module has undergone an extensive upgrade, star analysis for Star Color Calibration has changed as well. The selected stars to be used in star color calibration will be an improved selection of the brightest stars in the selected areas. The brightest stars will have better data (better statistics) than very weak stars, so we will have better intensities, per color channel, per star, as input for the model calculations.
  • ADJUSTED, MetaData panel, at application startup, you will now see the metadata panel partly as well to indicate to everyone that you can move the left side of the image viewer from left to right to show/hide the metadata of the current image.
MetaData visibleAtStart
  • ADJUSTED, Console Panel Registration Results, the console panel used to show messages about calibration frames that APP couldn't register. These messages have been removed since these messages really don't contain usefull information. Calibration frames are never registered so they are never used in registration, they are only used for calibration of the light frames. See this forum post as well:
  • FIXED, Analytical Graph of analytical results of processing, the graph did not show in APP 1.068. This is now fixed.
AnalyticalGraph sortedQuality
  • ADDED, NIKON CAMERA SUPPORT, added full support for the D7500, D850 models
  • ADDED, CANON CAMERA SUPPORT, added full support for the EOS 6D Mark II, 200D (Rebel SL2, KISS X9), 800D (Rebel T7i, KISS X9i), 1500D(Rebel T7, Kiss X90, 2000D), 3000D, M6, M100, 1D C models
  • IMPROVED, IMAGE VIEWER enable/disable OpenGL, at top left of the application, you can now disable/enable the OpenGL image viewer if APP detected that your system has at least OpenGL 2.0 capabilities. OpenGL is turned on by default.  The OpenGL label has been replaced by a switchbox.
    OpenGL button on
    OpenGL button off
  • IMPROVED, OPENGL IMAGE VIEWER, when zooming in, scrollbars appear to scroll in the image. The scrollbar thumbs are now more intuitive, they get smaller if the scrollamount gets larger.
  • IMPROVED, IMAGE VIEWER, the drawing of images to your screen will be disabled if the image viewer window is changing in size for whatever reason. Once the image viewer has a static size again, image drawing will continue. This ensures that the image zoomfactor is preserved better if the image viewer is changed.
  • IMPROVED, AUTO DDP STRETCH OUTLIER REJECTION MAP, the auto-stretch has been improved to give a much better and quicker visual impression of how outlier rejection is working in your integrations.
  • FIXED, LOADING INTEGRATION OUTPUT MAPS, if you loaded an old outlier rejection map, the map was loaded as both a light frame and a Rejection map. This is fixed, the frame will only be loaded as a Rejection Map. Same holds for normalization and weight/Drizzle maps.
  • IMPROVED, APPLICATION MEMORY MANAGEMENT, the total amount of memory that APP will consume will and should be lower now in most processing tasks, which will help with performance as well. This will especially hold if you use more than 4GBs or RAM for APP.
This topic was modified 4 years ago by Mabula-Admin

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