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wilsontie
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« on: January 01, 2008, 04:40:51 PM » |
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Date:30.12.2007 Time:8pm Place: Miri, Sarawak Camera: Canon Powershot S3 IS Stacked : 19 frames (15s each) using DSS & NeoImaging  |
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mymoon
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« Reply #1 on: January 01, 2008, 06:15:54 PM » |
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ahem RGB values for black is 0,0,0 and white is 255,255,255 using a 5x5pixel colour sampler your sky is 0,0,2 for some areas and 1,1,3 for others. The night sky appears black to our eye at a dark-sky site, but is not black. The light frames will usually record the sky with some colour, usually an unpleasant red-brown colour. If we want to show the deep-sky objects as they look in their natural state, as if we viewed them from space, we have to neutralize the colour of the sky background. Neutralizing the sky background does not meant to turn it to black. Look at values of skies used by other astronomers. I would go for around 30 to 100. This is a matter of personal taste/perception but the number 88,88,88 is easy to remember and safe to use  My preference is to have slightly more Blue( after all the sky is blue  ) BTW if your original images record the sky background as black, then you need to use longer exposures. Sifu's input is required on this; I stand corrected. My 2 sen. cheers |
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« Last Edit: January 01, 2008, 06:20:32 PM by mymoon »
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wilsontie
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« Reply #2 on: January 01, 2008, 06:20:19 PM » |
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ahem RGB values for black is 0,0,0 and white is 255,255,255 using a 5x5pixel colour sampler your sky is 0,0,2 for some areas and 1,1,3 for others. The night sky appears black to our eye at a dark-sky site, but is not black. The light frames will usually record the sky with some colour, usually an unpleasant red-brown color. If we want to show the deep-sky objects as they look in their natural state, as if we viewed them from space, we have to neutralize the colour of the sky background. Neutralizing the sky background does not meant to turn it to black. Look at values of skies used by other astronomers. I would go for around 30 to 100. This is a matter of personal taste/perception say the number 88,88,88 is safe to use My preference is to have slightly more Blue( after all the sky is blue ) BTW if your original images record the sky background as black, then you need to use longer exposures. Sifu's input is required on this; I stand corrected. My 2 sen. cheers  :?why i don't know what u r saying ?? may be tat r too detail for me? any simpler explanation? thanks? |
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mymoon
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« Reply #3 on: January 01, 2008, 06:30:52 PM » |
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:?why i don't know what u r saying ?? may be tat r too detail for me? any simpler explanation? thanks? maybe this would help http://www.astropix.com/HTML/J_DIGIT/DIGTECHS.HTMassumes familiarity with PhotoShop for post processing but the concensus is the sky is not Black . see samples of work by others. Your image acquisition is great but after image acquisition comes image processing. DSS is only the beginning of the workflow. Keep posting the pictures. cheers |
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kamayok3
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« Reply #4 on: January 01, 2008, 06:48:40 PM » |
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ahem RGB values for black is 0,0,0 and white is 255,255,255 using a 5x5pixel colour sampler your sky is 0,0,2 for some areas and 1,1,3 for others. The night sky appears black to our eye at a dark-sky site, but is not black. The light frames will usually record the sky with some colour, usually an unpleasant red-brown color. If we want to show the deep-sky objects as they look in their natural state, as if we viewed them from space, we have to neutralize the colour of the sky background. Neutralizing the sky background does not meant to turn it to black. Look at values of skies used by other astronomers. I would go for around 30 to 100. This is a matter of personal taste/perception say the number 88,88,88 is safe to use My preference is to have slightly more Blue( after all the sky is blue ) BTW if your original images record the sky background as black, then you need to use longer exposures. Sifu's input is required on this; I stand corrected. My 2 sen. cheers :?why i don't know what u r saying ?? may be tat r too detail for me? any simpler explanation? thanks? Hahaha...slowly you will understand what our sifu talking about. No comment on that!... Different point of view for different person. Nice wide field though. Tommy |
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wilsontie
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« Reply #5 on: January 01, 2008, 07:10:56 PM » |
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:?why i don't know what u r saying ?? may be tat r too detail for me? any simpler explanation? thanks? maybe this would help http://www.astropix.com/HTML/J_DIGIT/DIGTECHS.HTMassumes familiarity with PhotoShop for post processing but the concensus is the sky is not Black . see samples of work by others. Your image acquisition is great but after image acquisition comes image processing. DSS is only the beginning of the workflow. Keep posting the pictures. cheers means that my pics still can be improved using other softwares?? hmm...i try to use lah..haha |
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wilsontie
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« Reply #6 on: January 01, 2008, 07:12:03 PM » |
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ahem RGB values for black is 0,0,0 and white is 255,255,255 using a 5x5pixel colour sampler your sky is 0,0,2 for some areas and 1,1,3 for others. The night sky appears black to our eye at a dark-sky site, but is not black. The light frames will usually record the sky with some colour, usually an unpleasant red-brown color. If we want to show the deep-sky objects as they look in their natural state, as if we viewed them from space, we have to neutralize the colour of the sky background. Neutralizing the sky background does not meant to turn it to black. Look at values of skies used by other astronomers. I would go for around 30 to 100. This is a matter of personal taste/perception say the number 88,88,88 is safe to use My preference is to have slightly more Blue( after all the sky is blue ) BTW if your original images record the sky background as black, then you need to use longer exposures. Sifu's input is required on this; I stand corrected. My 2 sen. cheers :?why i don't know what u r saying ?? may be tat r too detail for me? any simpler explanation? thanks? Hahaha...slowly you will understand what our sifu talking about. No comment on that!... Different point of view for different person. Nice wide field though. Tommy ok..i will try to understand.thanks!!! |
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botok
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« Reply #7 on: January 01, 2008, 09:16:54 PM » |
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Wilsontie, nice pic bro. Langit kat sibu memang menarik. Saya masih ingat ketika saya di bintulu, langit kat sana memang menakjubkan. Saya rasa apa yang abg aziz cakap tu berkenaan dengan gambar anda, background color dia terlampau hitam meaning RGB value bagi background anda hampir kepada 0,0,0. Dengan ini anda akan hilang sedikit sebanyak detail dalam gambar tersebut. Kebanyakkan astrophotographer biasanya tidak akan set RGB value untuk black kepada 0,0,0 tetapi sedikit tinggi supaya lebih banyak detail pada gambar akan kelihatan. Tetapi tidak lah tinggi sangat nanti gambar jadik overexpose pulak (pun akan hilang detail). Kita boleh guna photoshop atau mana2 image processing software (GIMP pun boleh untuk open source) untuk set black value. Link yang abg aziz bagi tu memang spot on. Wilsontie, apa nilai ISO dan bukaan aperture yang kamu guna? |
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nsyahron
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« Reply #8 on: January 01, 2008, 09:39:25 PM » |
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Beautiful wilson!
Betelguese is nice orange, and you can spot just a tiny bit of M42 nebulosity.
Some people also use 15,15,20 for black and 245,245,245 for white
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wilsontie
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« Reply #9 on: January 01, 2008, 11:09:36 PM » |
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Wilsontie, nice pic bro. Langit kat sibu memang menarik. Saya masih ingat ketika saya di bintulu, langit kat sana memang menakjubkan. Saya rasa apa yang abg aziz cakap tu berkenaan dengan gambar anda, background color dia terlampau hitam meaning RGB value bagi background anda hampir kepada 0,0,0. Dengan ini anda akan hilang sedikit sebanyak detail dalam gambar tersebut. Kebanyakkan astrophotographer biasanya tidak akan set RGB value untuk black kepada 0,0,0 tetapi sedikit tinggi supaya lebih banyak detail pada gambar akan kelihatan. Tetapi tidak lah tinggi sangat nanti gambar jadik overexpose pulak (pun akan hilang detail). Kita boleh guna photoshop atau mana2 image processing software (GIMP pun boleh untuk open source) untuk set black value. Link yang abg aziz bagi tu memang spot on. Wilsontie, apa nilai ISO dan bukaan aperture yang kamu guna? i think i need to read a lot first or i will never understand what u all wanna explain to me  sorry because i really don't have any basic about all these....not good in physics things by the way, abg botok pernah kerja dekat Bintulu? takde apa2 gambar yg boleh share kat sini? oh..lupa pulak... all those pics took with ISO 400, f2.7, 15s exposure each. i m very new in processing these kind of photos..really just trial n errors. Beautiful wilson!
Betelguese is nice orange, and you can spot just a tiny bit of M42 nebulosity.
Some people also use 15,15,20 for black and 245,245,245 for white
:?ar....i really don't know what are the no. 15,15,20 Or 245,245,245 means. seemed very complicated to me but any way,thanks for ur comments! |
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« Last Edit: January 01, 2008, 11:12:49 PM by wilsontie »
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universe24
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« Reply #10 on: January 07, 2008, 09:42:46 AM » |
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Maybe I can give you some hints here. The 3 numbers you are looking at are refered to 3 color, red, green & blue, we called RGB channel in short. In digital image world, various kind of color produce through our computer monitor is actually the combination of RGB.
If we have a combination of RGB channel at 128:128:128, this will produce grey color. If we have 0:0:0, we have totally dark color where no information from RGB channel. Each channel have 256 level of intensity. So if 3 color channel have intensity level at 256:256:256, then will produce totally white.
Hope this help.
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To infinity, and beyond
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wilsontie
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« Reply #11 on: January 07, 2008, 12:35:56 PM » |
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Maybe I can give you some hints here. The 3 numbers you are looking at are refered to 3 color, red, green & blue, we called RGB channel in short. In digital image world, various kind of color produce through our computer monitor is actually the combination of RGB.
If we have a combination of RGB channel at 128:128:128, this will produce grey color. If we have 0:0:0, we have totally dark color where no information from RGB channel. Each channel have 256 level of intensity. So if 3 color channel have intensity level at 256:256:256, then will produce totally white.
Hope this help.
oh...i understand..many thanks for ur explaination |
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