hi rich
almost totally missed out on this thread. have done the processing for this image already before starting this thread post. but wanted to see how is everyone's approach to digital image processing for this sample image. will upload tonight.
Can you salvage this image??
hi chris and rest of those who tried processing,
Really appreciate everyone's efforts. there are various versions and different intentions, some focused on star colours and nebulosity, others on spectral density, etc. Everyone did very well in bringing up an almost washed out picture, and thanks to Michael for allowing us to process. He has great patience guiding this image for 1.5 hours!
But can't seem to find my previous processed image for this picture. had to do it again. here goes.
Really appreciate everyone's efforts. there are various versions and different intentions, some focused on star colours and nebulosity, others on spectral density, etc. Everyone did very well in bringing up an almost washed out picture, and thanks to Michael for allowing us to process. He has great patience guiding this image for 1.5 hours!
But can't seem to find my previous processed image for this picture. had to do it again. here goes.
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Airconvent
- Super Moderator
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hi chris and rest,
here's what i do and typically for any other deep sky FILM image. techniques will vary for the other mediums.
1) Vignetting removal. there are a variety of methods here, you can use the gradient removal tool in IRIS for example. you can also utilise some of the methods that Jerry Lodriguss advocates in his website, such as through Photoshop via masks and feathering.
Note however, unlike digital images, film images have a logarthmic response, so you must not use subtraction methods, but go in the direction of non-linear division instead.
2) Removal of green pixels. This is normally the result after vignetting removal. simply use colour range tool in PS with a little feathering to remove them.
3) The dynamic range of the resulting film image will now usually be low in contrast and dim. Use PS curves and levels to adjust and histogram stretch the image.
4) After this, it is pretty subjective from here and methods will vary from people to people. You may like to reduce the noise and grain as a result of histogram stretching. There are many noise reduction software out there like Neat Image, Noise Ninja, or even in PS using gaussian bluring but excluding the stars out (via masks)!
5) Don't forget to label your image!
here's what i do and typically for any other deep sky FILM image. techniques will vary for the other mediums.
1) Vignetting removal. there are a variety of methods here, you can use the gradient removal tool in IRIS for example. you can also utilise some of the methods that Jerry Lodriguss advocates in his website, such as through Photoshop via masks and feathering.
Note however, unlike digital images, film images have a logarthmic response, so you must not use subtraction methods, but go in the direction of non-linear division instead.
2) Removal of green pixels. This is normally the result after vignetting removal. simply use colour range tool in PS with a little feathering to remove them.
3) The dynamic range of the resulting film image will now usually be low in contrast and dim. Use PS curves and levels to adjust and histogram stretch the image.
4) After this, it is pretty subjective from here and methods will vary from people to people. You may like to reduce the noise and grain as a result of histogram stretching. There are many noise reduction software out there like Neat Image, Noise Ninja, or even in PS using gaussian bluring but excluding the stars out (via masks)!
5) Don't forget to label your image!
Hi,
I feel like I'm gonna ask a stupid question, but I'll never know if I dun ask. =)
Since the pics are taken with film, and then transferred to digital, won't data be lost? Just like when taken with Digital cameras?
Or does the film capture more detail and the scanner gets more detail than a digital cam?
Just curious.
I feel like I'm gonna ask a stupid question, but I'll never know if I dun ask. =)
Since the pics are taken with film, and then transferred to digital, won't data be lost? Just like when taken with Digital cameras?
Or does the film capture more detail and the scanner gets more detail than a digital cam?
Just curious.
Jeremy Ng
C8, CR-150HD, TMB 80 f/6
Orion SVP Intelliscope, AstroSlew I
Minolta Activa 12x50WA
C8, CR-150HD, TMB 80 f/6
Orion SVP Intelliscope, AstroSlew I
Minolta Activa 12x50WA
hi jeremy,
good question actually! see you never know...
well, you got to make sure you scan the film image properly using a dedicated film scanner. normally film negatives are easy. slide negatives due to their exposure latitude nature is harder, and sometimes it is better to overexpose your slides a little more than the suggested level in order to extract as much data onto the resulting digitally scanned image as possible. But we cannot say that a film image has more information than DSLR image, that is comparing apples to oranges. There are so many other factors at play. nevertheless it is important to make sure that information obtained and processed on the computer should be taken great care for not losing any information unnessarily. Another point to note is it is important to consider a right equipment match as well...in order words, are you having an optimum setup of your imaging device with the right telescope? Are you unsampling or oversampling your system...that is whether your equipment system is capturing images with a potential higher than the limitations of the atmospheric turbulence (oversampling) or vice versa. Ideally, we would want to have a system that is close to the Nyquist sampling limit. All this is important as well.
good question actually! see you never know...
well, you got to make sure you scan the film image properly using a dedicated film scanner. normally film negatives are easy. slide negatives due to their exposure latitude nature is harder, and sometimes it is better to overexpose your slides a little more than the suggested level in order to extract as much data onto the resulting digitally scanned image as possible. But we cannot say that a film image has more information than DSLR image, that is comparing apples to oranges. There are so many other factors at play. nevertheless it is important to make sure that information obtained and processed on the computer should be taken great care for not losing any information unnessarily. Another point to note is it is important to consider a right equipment match as well...in order words, are you having an optimum setup of your imaging device with the right telescope? Are you unsampling or oversampling your system...that is whether your equipment system is capturing images with a potential higher than the limitations of the atmospheric turbulence (oversampling) or vice versa. Ideally, we would want to have a system that is close to the Nyquist sampling limit. All this is important as well.
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universe24
- Posts: 227
- Joined: Thu Oct 02, 2003 12:26 am