Histogram with a RAW16 Colour Space

johnpd
Posts: 41
Joined: Fri Jun 01, 2018 8:30 am

Re: Histogram with a RAW16 Colour Space

#11

Post by johnpd »

Well I found a thread here about processing 16-bit Raw files. There was a mention of using PIPP to do the Debayering and convert the file to color. Unfortunately it can't do it with TIFF files as it does not recognize the compression of the SharpCap TIFF files. But it will handle the FITS files so I guess I am stuck with FITS if I want to use 16-bit.

JohnD
User avatar
admin
Site Admin
Posts: 13177
Joined: Sat Feb 11, 2017 3:52 pm
Location: Vale of the White Horse, UK
Contact:

Re: Histogram with a RAW16 Colour Space

#12

Post by admin »

Hi,

you can turn off the TIFF compression in the SharpCap settings (this will obviously not help for existing files, but will for future sessions)

Robin
johnpd
Posts: 41
Joined: Fri Jun 01, 2018 8:30 am

Re: Histogram with a RAW16 Colour Space

#13

Post by johnpd »

Thanks Robin,

I will give that shot when I get a chance. I will try to see how much of a difference it makes in the size of the file.

JohnD
johnpd
Posts: 41
Joined: Fri Jun 01, 2018 8:30 am

Re: Histogram with a RAW16 Colour Space

#14

Post by johnpd »

Robin,

I am getting some strange results with FITS files. No matter what I try as far as the Bayer pattern, the output FITS file is assigned GBRG. I tried Bayer=ON and tried to override the pattern (force RGGB which is what QHY says it should be), but the output FITS file header still says it is GBRG and this is the format PIPP converts to the proper colors. If I save the image as a non-compressed TIFF file, PIPP recognizes the Bayer pattern as RGGB which is the proper one. So I don't know what is going on. TIFF ends up as RGGB and FITS ends up as GBRG, at least that is how PIPP is interpreting the formats.

JohnD
johnpd
Posts: 41
Joined: Fri Jun 01, 2018 8:30 am

Re: Histogram with a RAW16 Colour Space

#15

Post by johnpd »

BTW, I discovered another way to open .TIFF files and convert them to color. Again it requires an "uncompressed" .TIFF image.

1. Change the file extension from .tif to .dng.
2. Open the modified file in RawTherapee.
3. It automatically displays the file in proper color. You do not have to tell it what Bayer pattern you used.

Much easier to use. I tried the compressed version of the file but it did not display anything and gave no message. From what the person who found this said was that the DNG format is based on TIFF.

JohnD
johnpd
Posts: 41
Joined: Fri Jun 01, 2018 8:30 am

Re: Histogram with a RAW16 Colour Space

#16

Post by johnpd »

Hi Robin,

Any response to why RAW16 mode is generating the wrong Bayer pattern in FITS files that I mentioned above?

JohnD
User avatar
admin
Site Admin
Posts: 13177
Joined: Sat Feb 11, 2017 3:52 pm
Location: Vale of the White Horse, UK
Contact:

Re: Histogram with a RAW16 Colour Space

#17

Post by admin »

Hi John,

unfortunately the problem with bayer patterns in FITS headers is that there is no general consensus among image processing applications about what the right value is. Take a saved image and load it into PixInsight and you might find it needs RGGB to debayer correctly. Load exactly the same file into AstroArt and it might need GBRG. This is all to do with whether the image processing application assumes the data in the FITS file starts at the bottom left or the top left of the image.

Sadly this means that it is impossible for SharpCap to put in 'correct' values for those fields, since what is correct in one application is wrong in another. Right now, it puts in one value and a FITS comment to note that in some applications an alternative might be needed. In the future I have plan to have a setting that will let you select which applications your FITS headers should be targeted to.

cheers,

Robin
johnpd
Posts: 41
Joined: Fri Jun 01, 2018 8:30 am

Re: Histogram with a RAW16 Colour Space

#18

Post by johnpd »

Thanks Robin,

Since I am able now to process a 16-bit TIFF file, I will go with that for now.

JohnD
Post Reply