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ASTRO: DeepSkyStacker processing



 
 
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  #1  
Old September 20th 08, 12:00 AM posted to alt.binaries.pictures.astro
Robert Price[_2_]
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Posts: 165
Default ASTRO: DeepSkyStacker processing

I recently tried using DeepSkyStacker with my Canon 40D DSLR files.
It took 15.5 minutes just to register and stack three 16 bit TIF
files. I tried using RAW files and it took only 3 minutes, but what a
difference in color. After the register and stack process the rest of
the process was as similar as I could get it to be. I have been using
TIF files because I can use Noise Ninja before stacking to reduce
noise from the Canon camera. Looking through my astro download images
from the web I see several M33 images that have the yellow color to
the center third of the galaxy, but most images people post seem to
show M33 as almost all blue (except for the h alpha nebulae). The
three RAW and 16 bit TIF files (which were converted using the canon
utility from the RAW files) were each 20 minute exposures with a
Hutech modified Canon 40D at 100ASA. Scope was an NP-127.

Robert Price




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  #2  
Old September 20th 08, 04:16 PM posted to alt.binaries.pictures.astro
J McBride
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Posts: 274
Default ASTRO: DeepSkyStacker processing

Hi Robert, You don't really need to pre-process the noise. Deep sky stacker
has a feature that will get rid of hot and cold pixels automatically. This
image was taken with no darks or flats using that feature.







"Robert Price" wrote in message
...
I recently tried using DeepSkyStacker with my Canon 40D DSLR files.
It took 15.5 minutes just to register and stack three 16 bit TIF
files. I tried using RAW files and it took only 3 minutes, but what a
difference in color. After the register and stack process the rest of
the process was as similar as I could get it to be. I have been using
TIF files because I can use Noise Ninja before stacking to reduce
noise from the Canon camera. Looking through my astro download images
from the web I see several M33 images that have the yellow color to
the center third of the galaxy, but most images people post seem to
show M33 as almost all blue (except for the h alpha nebulae). The
three RAW and 16 bit TIF files (which were converted using the canon
utility from the RAW files) were each 20 minute exposures with a
Hutech modified Canon 40D at 100ASA. Scope was an NP-127.

Robert Price






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ID:	2188  
  #3  
Old September 20th 08, 04:55 PM posted to alt.binaries.pictures.astro
Robert Price[_2_]
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Posts: 165
Default ASTRO: DeepSkyStacker processing

J

There is another type of noise in my Canon 40D images that is not
related to hot pixels. What I was trying to illustrate in the two
images was the difference in color. Why should there be any
difference since I am stacking the same files, RAW files and TIF files
converted from those RAW files?

Robert

DeepSkyStacker On Sat, 20 Sep 2008 11:16:29 -0400, "J McBride"
wrote:

Hi Robert, You don't really need to pre-process the noise. Deep sky stacker
has a feature that will get rid of hot and cold pixels automatically. This
image was taken with no darks or flats using that feature.







"Robert Price" wrote in message
.. .
I recently tried using DeepSkyStacker with my Canon 40D DSLR files.
It took 15.5 minutes just to register and stack three 16 bit TIF
files. I tried using RAW files and it took only 3 minutes, but what a
difference in color. After the register and stack process the rest of
the process was as similar as I could get it to be. I have been using
TIF files because I can use Noise Ninja before stacking to reduce
noise from the Canon camera. Looking through my astro download images
from the web I see several M33 images that have the yellow color to
the center third of the galaxy, but most images people post seem to
show M33 as almost all blue (except for the h alpha nebulae). The
three RAW and 16 bit TIF files (which were converted using the canon
utility from the RAW files) were each 20 minute exposures with a
Hutech modified Canon 40D at 100ASA. Scope was an NP-127.

Robert Price




  #4  
Old September 20th 08, 06:42 PM posted to alt.binaries.pictures.astro
Rick Johnson[_2_]
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Posts: 3,085
Default ASTRO: DeepSkyStacker processing



Robert Price wrote:
I recently tried using DeepSkyStacker with my Canon 40D DSLR files.
It took 15.5 minutes just to register and stack three 16 bit TIF
files. I tried using RAW files and it took only 3 minutes, but what a
difference in color. After the register and stack process the rest of
the process was as similar as I could get it to be. I have been using
TIF files because I can use Noise Ninja before stacking to reduce
noise from the Canon camera. Looking through my astro download images
from the web I see several M33 images that have the yellow color to
the center third of the galaxy, but most images people post seem to
show M33 as almost all blue (except for the h alpha nebulae). The
three RAW and 16 bit TIF files (which were converted using the canon
utility from the RAW files) were each 20 minute exposures with a
Hutech modified Canon 40D at 100ASA. Scope was an NP-127.

Robert Price


Something in the TIFF conversion is screwing up the color. Your RAW
file is close to correct. There is very little color in this galaxy. I
had to really lean on the color saturation to get any at all to come
out. Many imagers I've talked to say the same. Unfortunately, there
are a ton of photos of this one out there in which the processor, so
shook by seeing little color Photoshopped the color to agree with a
typical spiral with a golden core and blue arms. This is totally
artificial except in cases of very low resolution where the few blue
star clouds aren't resolved so when saturation is turned way up you do
get this result. But once you resolve the clouds as you have you see
the spaces between are rather colorless with only a hint of yellow.
Below is my G2 color balanced version with saturation turned up so you
see some color. I did suppress this saturation on the HII regions as
then they'd have looked really awful. So colors are quite accurate I
believe but more saturated than reality. It is a surprisingly blah
galaxy for color but for the HII regions.

G2 color balancing is when you adjust the blue and green channels such
that a G2 star, like our sun, appears pure white whether it is a faint
or bright star. This compensates for blue extinction in the atmosphere
as well as filter and CCD spectral response.

Rick


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  #5  
Old September 20th 08, 09:33 PM posted to alt.binaries.pictures.astro
J McBride
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Posts: 274
Default ASTRO: DeepSkyStacker processing

I get a little color difference when I use TIFF v.s. JPEG v.s. RAW. in
deepsky stacker. I usually take the AUTO image that deep sky stacker makes
and process that one. I save it as a 16bit and process it in PS7 to my own
liking.

Joe


"Robert Price" wrote in message
...
J

There is another type of noise in my Canon 40D images that is not
related to hot pixels. What I was trying to illustrate in the two
images was the difference in color. Why should there be any
difference since I am stacking the same files, RAW files and TIF files
converted from those RAW files?

Robert

DeepSkyStacker On Sat, 20 Sep 2008 11:16:29 -0400, "J McBride"
wrote:

Hi Robert, You don't really need to pre-process the noise. Deep sky

stacker
has a feature that will get rid of hot and cold pixels automatically.

This
image was taken with no darks or flats using that feature.







"Robert Price" wrote in message
.. .
I recently tried using DeepSkyStacker with my Canon 40D DSLR files.
It took 15.5 minutes just to register and stack three 16 bit TIF
files. I tried using RAW files and it took only 3 minutes, but what a
difference in color. After the register and stack process the rest of
the process was as similar as I could get it to be. I have been using
TIF files because I can use Noise Ninja before stacking to reduce
noise from the Canon camera. Looking through my astro download images
from the web I see several M33 images that have the yellow color to
the center third of the galaxy, but most images people post seem to
show M33 as almost all blue (except for the h alpha nebulae). The
three RAW and 16 bit TIF files (which were converted using the canon
utility from the RAW files) were each 20 minute exposures with a
Hutech modified Canon 40D at 100ASA. Scope was an NP-127.

Robert Price






  #6  
Old September 21st 08, 07:23 PM posted to alt.binaries.pictures.astro
Skywise
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Posts: 318
Default ASTRO: DeepSkyStacker processing

Robert Price wrote in
:

There is another type of noise in my Canon 40D images that is not
related to hot pixels. What I was trying to illustrate in the two
images was the difference in color. Why should there be any
difference since I am stacking the same files, RAW files and TIF files
converted from those RAW files?


Although both RAW and TIF are uncompressed, it could be bit depth.

On my Nikon D200, RAW files are 12 bits per color plane rathar
than the usual 8. When you convert them to TIF you may be losing
those extra bits and thus losing dynamic range.

TIF as a format is capable of more than 8 bits per plane. Check
your software to see if you can retain those extra bits when you
convert.

Brian
--
http://www.skywise711.com - Lasers, Seismology, Astronomy, Skepticism
Seismic FAQ: http://www.skywise711.com/SeismicFAQ/SeismicFAQ.html
Quake "predictions": http://www.skywise711.com/quakes/EQDB/index.html
Sed quis custodiet ipsos Custodes?
  #7  
Old September 21st 08, 11:10 PM posted to alt.binaries.pictures.astro
Robert Price[_2_]
external usenet poster
 
Posts: 165
Default ASTRO: DeepSkyStacker processing

Brian,

I always convert to 16 bit TIF files. I have tried using the JPEG
files that are generated with the RAW files in the camera with the
same result as the TIF files.

Robert

On Sun, 21 Sep 2008 18:23:24 GMT, Skywise
wrote:

Robert Price wrote in
:

There is another type of noise in my Canon 40D images that is not
related to hot pixels. What I was trying to illustrate in the two
images was the difference in color. Why should there be any
difference since I am stacking the same files, RAW files and TIF files
converted from those RAW files?


Although both RAW and TIF are uncompressed, it could be bit depth.

On my Nikon D200, RAW files are 12 bits per color plane rathar
than the usual 8. When you convert them to TIF you may be losing
those extra bits and thus losing dynamic range.

TIF as a format is capable of more than 8 bits per plane. Check
your software to see if you can retain those extra bits when you
convert.

Brian


  #8  
Old September 21st 08, 11:32 PM posted to alt.binaries.pictures.astro
Robert Price[_2_]
external usenet poster
 
Posts: 165
Default ASTRO: DeepSkyStacker processing

Rick,

I d not believe the proplem is in the TIF file conversion. I even
tried TIF conversion without "embed ICC profile in image". I always
convert to 16 bit TIF files. I have tried using the JPEG files that
are generated with the RAW files in the camera with the same result as
the TIF files. DeepSkyStacker allows you to superimpose the RGB
channels to get a neutral background. When I do not do this RGB
adjustment in DeepSkyStacker but save the file and use CCDStack set
background feature or adjust the RGB channels in photoshop to get a
neutral background the result in both cases is a blue galaxy with
none of the yellow.

Robert

On Sat, 20 Sep 2008 12:42:47 -0500, Rick Johnson
wrote:



Robert Price wrote:
I recently tried using DeepSkyStacker with my Canon 40D DSLR files.
It took 15.5 minutes just to register and stack three 16 bit TIF
files. I tried using RAW files and it took only 3 minutes, but what a
difference in color. After the register and stack process the rest of
the process was as similar as I could get it to be. I have been using
TIF files because I can use Noise Ninja before stacking to reduce
noise from the Canon camera. Looking through my astro download images
from the web I see several M33 images that have the yellow color to
the center third of the galaxy, but most images people post seem to
show M33 as almost all blue (except for the h alpha nebulae). The
three RAW and 16 bit TIF files (which were converted using the canon
utility from the RAW files) were each 20 minute exposures with a
Hutech modified Canon 40D at 100ASA. Scope was an NP-127.

Robert Price


Something in the TIFF conversion is screwing up the color. Your RAW
file is close to correct. There is very little color in this galaxy. I
had to really lean on the color saturation to get any at all to come
out. Many imagers I've talked to say the same. Unfortunately, there
are a ton of photos of this one out there in which the processor, so
shook by seeing little color Photoshopped the color to agree with a
typical spiral with a golden core and blue arms. This is totally
artificial except in cases of very low resolution where the few blue
star clouds aren't resolved so when saturation is turned way up you do
get this result. But once you resolve the clouds as you have you see
the spaces between are rather colorless with only a hint of yellow.
Below is my G2 color balanced version with saturation turned up so you
see some color. I did suppress this saturation on the HII regions as
then they'd have looked really awful. So colors are quite accurate I
believe but more saturated than reality. It is a surprisingly blah
galaxy for color but for the HII regions.

G2 color balancing is when you adjust the blue and green channels such
that a G2 star, like our sun, appears pure white whether it is a faint
or bright star. This compensates for blue extinction in the atmosphere
as well as filter and CCD spectral response.

Rick


  #9  
Old September 27th 08, 12:54 PM
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