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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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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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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 |
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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 -- Correct domain name is arvig and it is net not com. Prefix is correct. Third character is a zero rather than a capital "Oh". |
#5
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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
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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
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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
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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
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juesting40
Does the dog know the proverb, too? The little boy did not like the look of the barking dog. "It's all right," said a gentleman, "don't be afraid. Don't you know the proverb: Barking dogs don't bite?" Sodium Borohydride"Ah, yes," answered the little boy. "I know the proverb, but does the dog know the proverb, too?" Waste water treatmentWater treatment chemicals
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