Re: Version 1.8 HDR and SV Decon
Posted: Fri Aug 12, 2022 2:31 pm
Hi,
yes I think the preview issue is not in Guy's notes, but the detailed description is Guy's work!
Regrarding the stars- that seems to be an aesthetic/artistic issue. In a way as Astrophotographers we probably had been spoiled by all the shortcomings of the gear used in the past. We are so used to the "old school" look we assume its actually natural.
Decon tries to remove any dispersion caused by athmosphere and/or optical train. The PSF is called that way, because the star in fact is a point spreaded over multiple pixels. There is no "natural"fade to a point. It's just that we got used to see stars like that.
If You were at ISS or expose Your image using HSS or the like, You would see the stars just as airy disks only limited by the optics. Now SVD is trying to "undo" the way a point has been spread over many pixels,(point spread function = PSF), it offers to undo as many PSFs as needed, varying throughout the image.
Whether or not You like the "unnatural" point look is a matter of taste, just as with color: white color in blown out areas (e.g. M42 center) seems "natural to us, but is simply plain wrong, we just got used to that, by looking at thousands of white-core M42 images, so we believe it is white by nature. Similar is valid e.g. for purple vs red H-II regions.
ST's approach is to enable scientificly "correct" representation as far as possible, but ST does not nail You on that. There are always options to create images in "old-school" look e.g. FilmDev as stretching tool, or "Artistic" mode in Color.
Clear Skies,
Jochen
yes I think the preview issue is not in Guy's notes, but the detailed description is Guy's work!
Regrarding the stars- that seems to be an aesthetic/artistic issue. In a way as Astrophotographers we probably had been spoiled by all the shortcomings of the gear used in the past. We are so used to the "old school" look we assume its actually natural.
Decon tries to remove any dispersion caused by athmosphere and/or optical train. The PSF is called that way, because the star in fact is a point spreaded over multiple pixels. There is no "natural"fade to a point. It's just that we got used to see stars like that.
If You were at ISS or expose Your image using HSS or the like, You would see the stars just as airy disks only limited by the optics. Now SVD is trying to "undo" the way a point has been spread over many pixels,(point spread function = PSF), it offers to undo as many PSFs as needed, varying throughout the image.
Whether or not You like the "unnatural" point look is a matter of taste, just as with color: white color in blown out areas (e.g. M42 center) seems "natural to us, but is simply plain wrong, we just got used to that, by looking at thousands of white-core M42 images, so we believe it is white by nature. Similar is valid e.g. for purple vs red H-II regions.
ST's approach is to enable scientificly "correct" representation as far as possible, but ST does not nail You on that. There are always options to create images in "old-school" look e.g. FilmDev as stretching tool, or "Artistic" mode in Color.
Clear Skies,
Jochen