From: Mark Gaffney <markgaffney@me.com>

Date: August 31, 2009 11:07:05 AM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Colour Jupiter from Ray


Hi Milton, 

My problem evidently isn`t darkness of image. I just tried the suggestions you`ve given Ray & I`m not getting a satisfactory result. My Jupiter in the movie is riding right up in the top left & is partly under the red border area. Here`s a jpg version of the stacking result from the other night;

Mail Attachment

I was lucky to get even this on the night I did it. I`d have tried again tonight but I was busy with other things & the moon was rather bright...It`s about to slip behind some trees I have to the west right now..


Mark.

On 01/09/2009, at 2:08 AM, Milton Aupperle wrote:

Hi Ray;


The "Curves" he's referring to is a post capture tool in PhotoShop, very similar to "Curves" in the Image Processing part of Astro IIDC (see page both 58 and 59 of the Astro IIDC Manual). Both are used to stretch the image in a non linear way.


As Allan pointed out, you can use the Gamma to change the brightness / contrast to some degree, butt IMHO your better off adjusting the image brightness (longer exposure,  more Gains / Brightness or binning 2x2) to decent levels (likely the brightest part of the image being 60% or higher of the image brightness).


Achieving proper brightness when your sitting in the dark can be challenging, however there is a live tool in Astro IIDC to determine if your hitting the correct brightness before you take an image. Read the sections for "Saturated Pixel Cutoff Limit: xxx (0 to 255)." on page 71 and then "Show Saturated" on pages 82 and 83.


Quote from page 83:


Note that you can also use this to make sure your targets have sufficient brightness when  imaging. For example, say you were imaging saturn and wanted to make sure that the disk and  rings are at least 50 % brightness. If you set the Cutoff Limit to 128 (128/255 is ~50%) , then as  you adjust your exposure time or gain sliders you will be able to see the rings  and disk will just  start to turn red. Then you know that your getting at least 50% brightness. 


Also for stacking, you can likely improve the stacked images and get something better out of them by using these two things when stacking.


In the "Stacking Options.." window:


1) Check mark "Histogram expand brightness of all frames used for pixel alignment." (explained on page 35 of the manual)


This was specifically designed for cases where you have to under exposes the movie or you need to use the darker portions of the movie for finding good alignment features.


2) Check mark  "Bin Frames 2x2 and auto subtract background before stacking." (explained on page 37 of the manual)


This can be used to amplify faint DSO objects and can be useful If you have really dark planetary images.


Lastly, for darker planetary bodies or if I need to shoot with higher frame rates, you may want to consider using "Binned 2x2 Monochrome" for the ""Camera Display Format" pop up menus (see pages 76 and 77 of the manual). I have used it under poor skies to image Saturn :


http://www.outcastsoft.com/AstroImages/Saturn20090502MJA.jpg


at much higher frame rates than I would have normally and got something out of a bad night:


HTH..


Milton Aupperle


On 31-Aug-09, at 6:33 AM, Ray Byrne wrote:

<*>[Attachment(s) from Ray Byrne included below]


Hi Guys,


On Saturday/Sunday I took some movies of Jupiter in pretty bad seeing  

but actually better than the last few weeks. Out of them I got one OK  

result which I've posted in the photos section on our site. When I  

came to do the colour processing (it was in the small hours) I got  

muddled-up somehow and and kept getting a mono result. Frustrated and  

impatient I sent the LRGB set to my mate Mick Hyde to do the colour  

bit for me which is the result you'll see.


Now he uses the same gear as me but being a PC/Windows guy uses the  

K3CCD Tools/ Registax combo for capture and processing and remarked  

that my LRGB set were very dark. To quote Mick he said " Ray, There  

you go. The images were very dark though, I had stretch them with  

curves in PS. I think you need to check your histogram whilst  

capturing and boost the gain a bit."  Two things about this what would  

be the equivalent in Astro IIDC of the histogram he's referring to?  

and should a fiddle with the gain? As regards the gain I always keep  

that set to 1.00 and use brightness instead, but of course the more  

you increase the brightness the noisier the resultant image is it  

seems, should a adjust the gain? Here are reduced sized files before  

processing in PS:


(actually this is the first time I've seen them in daylight they are  

very dark)




<*>Attachment(s) from Ray Byrne:


<*> 4 of 4 Photo(s) http://groups.yahoo.com/group/Astro_IIDC/attachments/folder/579718618/item/list 

  <*> blue.jpg

  <*> green.jpg

  <*> lumi.jpg

  <*> red.jpg