In that thread I reached an impasse with the way files are displayed - it seemed to me that the histogram was all wrong.
That thread has received no replies. so I concluded either that the answer was obvious and people were leaving me to find it, or that it was very unobvious and no-one could help.
So I took a different series of images last night in tiff format, one of which is attached to this thread. No calibration applied.
That also presented a very odd histogram and opened an entirely blue screen in ASTAP.
The same happened when opening the corresponding .fits file. Same screen, same histogram.
However, when opened in CCdCiel, both these files open fine.
Which leads me to wonder whether there is a bug somewhere.
I tried using ASTAP in Windows, which has no probs opening the file. The difference seems to be that the debayer function in the AMD64.deb version does not seem to work as expected in Linux (Ubuntu 20.04.1). When I select Autocorrect Colours, the file opens but the predominant colour is green with some purple.
Best
R
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
and in para 2.2.2 of the .pdf article linked from there:
If you use an OSC camera of make ZWO, caution is advised when the 'native' camera driver is used: the ZW Software Development Kit (SDK) enables the user in the image acquisition software to control settings that influence the white balance of a displayed color image. This is achieved by two parameters, WBR and WBB, data range 1 to 100, the default values are WBR = 52 and WBB = 95. The intensities of the red channel will be multiplied by WBR/50 and the intensities of the blue channel by WBB/50. Unfortunately the results of this multiplication are also written to disk in the FITS file. So it is important to set the values of both parameters to 50 and subsequently apply 'Save Config'; only in this way, the real raw intensities will be saved to disk in the FITS files, see [6]. Since the data coming from the camera are saved in FITS files which usually have the data format '16-bit integer', otherwise rounding errors and clipping of high values will arise. Such a complication is generally avoided when the ASCOM camera driver is used instead of the 'native' camera driver. A related issue with white balance factors also emerges with cameras of make
Svbony [7]
I am using the indi-asi driver, not the native ZWO, but appear to have this problem.
Have adjusted the WB(B) and WB(R) to 50 and saved as recommended.
Next decent night will try again.
Best
R
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Hi Han
This is a fork from my other thread https://sourceforge.net/p/astap-program/discussion/general/thread /b205e65ca0/#570d which asks for help with atmospheric dispersion.
In that thread I reached an impasse with the way files are displayed - it seemed to me that the histogram was all wrong.
That thread has received no replies. so I concluded either that the answer was obvious and people were leaving me to find it, or that it was very unobvious and no-one could help.
So I took a different series of images last night in tiff format, one of which is attached to this thread. No calibration applied.
That also presented a very odd histogram and opened an entirely blue screen in ASTAP.
The same happened when opening the corresponding .fits file. Same screen, same histogram.
However, when opened in CCdCiel, both these files open fine.
Which leads me to wonder whether there is a bug somewhere.
Any ideas?
Best
R
I tried using ASTAP in Windows, which has no probs opening the file. The difference seems to be that the debayer function in the AMD64.deb version does not seem to work as expected in Linux (Ubuntu 20.04.1). When I select Autocorrect Colours, the file opens but the predominant colour is green with some purple.
Best
R
I found the solution to the 'odd histogram'. Posting here in case it helps anyone.
The problem is described here
https://pixinsight.com/forum/index.php?threads/guide-to-preprocessing-of-raw-data-with-pixinsight.11547/
and in para 2.2.2 of the .pdf article linked from there:
If you use an OSC camera of make ZWO, caution is advised when the 'native' camera driver is used: the ZW Software Development Kit (SDK) enables the user in the image acquisition software to control settings that influence the white balance of a displayed color image. This is achieved by two parameters, WBR and WBB, data range 1 to 100, the default values are WBR = 52 and WBB = 95. The intensities of the red channel will be multiplied by WBR/50 and the intensities of the blue channel by WBB/50. Unfortunately the results of this multiplication are also written to disk in the FITS file. So it is important to set the values of both parameters to 50 and subsequently apply 'Save Config'; only in this way, the real raw intensities will be saved to disk in the FITS files, see [6]. Since the data coming from the camera are saved in FITS files which usually have the data format '16-bit integer', otherwise rounding errors and clipping of high values will arise. Such a complication is generally avoided when the ASCOM camera driver is used instead of the 'native' camera driver. A related issue with white balance factors also emerges with cameras of make
Svbony [7]
I am using the indi-asi driver, not the native ZWO, but appear to have this problem.
Have adjusted the WB(B) and WB(R) to 50 and saved as recommended.
Next decent night will try again.
Best
R
Strange however that in Win ASTAP displayed the .fit and .tif files correctly, where in Linux it didn't.
R