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A Welcome Note To Newbies

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  #151  
Old 11-20-2006, 06:21 AM
shahzadmasih shahzadmasih is offline
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Re: A Welcome Note To Newbies

Hi, This post is very informative, however I would like some specific information. If someone can help me then please send me a private message. Best Regards,
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  #152  
Old 11-20-2006, 10:56 AM
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Swampy Swampy is offline
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Re: A Welcome Note To Newbies

shahzadmasih

You're going to have to be more specific. What do you need help with?
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  #153  
Old 12-20-2006, 01:14 PM
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CharlesBell CharlesBell is offline
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Talking Re: A Welcome Note To Newbies

Thanks to all of you. I have just joined in. This is a lot more fun than I expected.

I work mainly on astronomy images and have a lot more to learn. I usually image comets with a 12 inch telescope and a CCD camera, (Lately all the comets are very faint). I am working on an image of a globular cluster called M2.

I have some digitized family album images to work on and share with my relatives.

Plus I have dozens of images taken with a Nikon D50 of the flowers around my house from last spring and summer.

It was quite by accident finding this forum. Already enjoyed Natalie's music
and a few winking avatars.

Hope to hear from you,

Charles
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  #154  
Old 12-20-2006, 02:13 PM
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Craig Walters Craig Walters is offline
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Re: A Welcome Note To Newbies

welcome, charlesbell.

would love to see some of your astronomy photos. every once in a while i'll visit the nasa site(s) and marvel at some of their imagery. and not that i expect you'll get the same thing with a 12 inch as they do with the hubble, but i do find it fascinating.

post them in the photophaphy forum if you just want to show off, or maybe in the art forums if you'd like to see what others might do with them.
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  #155  
Old 12-20-2006, 03:26 PM
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CharlesBell CharlesBell is offline
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Red face Re: A Welcome Note To Newbies

The latest version of the image I am working on today was just posted to:

http://bellsouthpwp2.net/c/h/charbell/M2-09142006.jpg

This is an image of a globular cluster named M2 in the Messier catalog.
Its a glob of over 150,000 stars. Its looks like a fuzz ball when you look at it in the telescope eyepiece.

The sky size of this object fits well with my equipment setup.

I use a 12 inch Meade SCT telescope with an F/6.3 focal reducer, and an SBIG ST-2000XCM single shot color CCD camera guided with an AO-7 adaptive optics unit. This is the same setup I use for doing my comet studies.

This image is a stacked composite made from ten consecutive 120 second exposures. The images were calibrated with dark frame subtraction and flat field correction, and then each R,G,B color channel was extracted and aligned with an image registration program, the aligned color channel images were median combined, then brought into PhotoshopCS2 one color channel at a time via the NASA/ESA Fits Liberator plugin using a log stretch on the intensities. Then it is basic layers processing with Levels, Curves, Color, Saturation, etc.

I would certainly entertain any comments especially critical ones.

That's my story and I'm sticking to it!!!
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  #156  
Old 12-20-2006, 09:32 PM
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Craig Walters Craig Walters is offline
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Re: A Welcome Note To Newbies

that's very cool

you realize, of course, that everything after '12 inch Meade" all went over my head, right? astronomy jargon! he wants me to understand astronomy jargon! hehe, ok, i actually probably understood more than i'm letting on. for us lay folk, i'm guessing that you basically are allowing and correcting for the displacement blur in the image due to the rotation of the planet during the time lapse(es), no?

but why bring them in one channel at a time? red shift?
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  #157  
Old 12-21-2006, 10:42 AM
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CharlesBell CharlesBell is offline
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Smile Re: A Welcome Note To Newbies

First off, the object is a star cluster. Its way way out there. So there's no rotation to worry about. You are right about considerations for planet rotation.

There is a slight image alignment difference between each image that's unavoidable. So all the images have to be aligned though a process called image registration. Then you stack the images which is basically runs a pixel addition process on the images. A median combine is the best overall process to stack astronomical images. There are random cosmic ray hits that get eliminated this way. Sometimes I get satellites tracking through the field of view. The median combine improves the data signal to noise ratio in the combined image.

A CCD camera integrates the incoming light, but there is read noise when the chip pixels are read. If the exposure is too long the pxels get saturated. So the basic technique is to median combine multiple images.

The image files downloaded from the CCD Camera are in a Debayer color matrix format that cannot be aligned and combined directly. Image registration is at the subpixel level. This is over my head.

So I have to separate out the red, blue, and green color components of each image into there own separate sub file, so they can be aligned.

All the red image files are then stacked/median combined. Then the green, then blue. Any order.

I end up with three files (R, G, and B) saved in Fits format. These are actually 16 but grey scale image files for each color.

The NASA/ESA Fits Liberator plugin reads Fits files and provides lots of options for histogram stretching. This is very necessary to see all the detail in bright globular star cluster.

I could use the same programs that I use for image acquisition, registration, etc.. to create an RGB tiff file, but the Fits Liberator seems to do a better job.

I open Photoshop and create a new blank RGB image and bring in the red, green, and blue component images and copy and paste them into the R, B, and G channels.

Then process with Levels, Curves, photoshop tools to bring out the detail and suppress background noise.

Now this last part is why I am here on this site.

Everything up to this point is busy work requiring no special skills as that part of the process is very mechanical.


I think I am going to post a new thread about this because its probably off the jist of the newbie thread.

Thanks for the welcome.
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  #158  
Old 05-21-2007, 05:27 AM
dayananda dayananda is offline
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Re: A Welcome Note To Newbies

Thanks Jak! Happy to find a place as this!

Registered just an hour before. Will utilize all the help available.

Also, will try to be of help!
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  #159  
Old 05-25-2007, 09:32 PM
serna1 serna1 is offline
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Re: A Welcome Note To Newbies

Hi, not sure where to introduce myself, but my name is Patty and I discovered photoshop about 2 years ago. I love working with pictures (actually my children's pictures I started by making small corrections then to creating actual portraits with various backdrops... I'm still learning everyday something new about photoshop and I hope that I will learn even more by being a member of this really cool site Thanks for in advance for all the cool things I know I will learn!

Patty
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  #160  
Old 05-30-2007, 07:48 AM
JackBush JackBush is offline
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Re: A Welcome Note To Newbies

Hi All,

I am a newbie to Retouch Pro. Looks like a great site and I'm looking forward to getting all kinds of tips.

I use Photoshop Elements 3 and found this site via a posting on the Adobe Forums site.

Watch for my questions. (But I promise to search first!)
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