Last night I used Sharpcap to take about 30-1 minute pictures of the Veil Nebula using Sharpcap and then turned off Sharpcap and used Nina to do the same. I am using the QHY163C camera. The proper bayer pattern is BGGR for this camera. I processed the pictures separately in Deep Sky Stacker. The Nina pictures process correctly using BGGR but I had to change DSS to GRBG for the Sharpcap pictures to process correctly. Is Sharpcap somehow storing the fits images differently than Nina? Using BGGR with Sharpcap fits files worked properly for years up until a few months ago. Something seems to have changed.
Mike
Bayer Matrix Confusion
-
admin
- Site Admin
- Posts: 13319
- Joined: Sat Feb 11, 2017 3:52 pm
- Location: Vale of the White Horse, UK
- Contact:
Re: Bayer Matrix Confusion
Hi,
I don't think there's been a change in SharpCap that would relate to this, but there is definitely confusion regarding the way that layer patterns are defined and used when processing fits files. The problem starts with the fact that processing software doesn't agree on what the correct Bayer pattern for a file is. For instance you could load the same fits file into pixinsight and AstroArt and you would need to use RGGB in one piece of software and GBRG in the other to get correct results
The confusion is deepened by the fact that strictly speaking the image data in the fits file should start with the pixel in the bottom left corner of the image. However SharpCap has always started with the top left corner of the image and I have been reluctant to change this because it would cause problems of the sort you are describing where people would have to update their processing workflow. SharpCap 3.3 will add a new fits header called ROWORDER which will let compatible processing software know that SharpCap has started with the top left corner of the image. I'm not sure whether this will have a big impact on how the Bayer pattern is interpreted though – that would depend on the implementation in the individual pieces of processing software.
Certainly, looking back over the changes that have made to fits file writing in SharpCap 3.2, there's been nothing changed in the last year that would have affected how the Bayer pattern is interpreted as far as I can tell.
Cheers, Robin
I don't think there's been a change in SharpCap that would relate to this, but there is definitely confusion regarding the way that layer patterns are defined and used when processing fits files. The problem starts with the fact that processing software doesn't agree on what the correct Bayer pattern for a file is. For instance you could load the same fits file into pixinsight and AstroArt and you would need to use RGGB in one piece of software and GBRG in the other to get correct results
The confusion is deepened by the fact that strictly speaking the image data in the fits file should start with the pixel in the bottom left corner of the image. However SharpCap has always started with the top left corner of the image and I have been reluctant to change this because it would cause problems of the sort you are describing where people would have to update their processing workflow. SharpCap 3.3 will add a new fits header called ROWORDER which will let compatible processing software know that SharpCap has started with the top left corner of the image. I'm not sure whether this will have a big impact on how the Bayer pattern is interpreted though – that would depend on the implementation in the individual pieces of processing software.
Certainly, looking back over the changes that have made to fits file writing in SharpCap 3.2, there's been nothing changed in the last year that would have affected how the Bayer pattern is interpreted as far as I can tell.
Cheers, Robin