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Orpington Astronomical Society

Astronomy => Astrophotography => Topic started by: Fay on Oct 11, 2007, 09:49:36

Title: Processing question for the Big Four!
Post by: Fay on Oct 11, 2007, 09:49:36
Please can you tell me, do you all pay a lot of attention to Gradient Removal & Dark & Light points when processing your images?
It seems such a lot of palaver, if it is neccessary, then I will study it in depth. If not, then....................!!!!?????%%****


Fay
Title: Re: Processing question for the Big Four!
Post by: Rocket Pooch on Oct 11, 2007, 12:17:10
If there is not gradient then no,

If there is then yes,

Bit of a chicken and egg question,

Fay, the thing to do is measure the black points in the image, you do this in AA by moving the mouse around, look at the values, if you have a consistantly higher ADU reading from one end of the frame than the other you have a gradient, you can then use a gradient removal tool to get rid of it.  http://www.msb-astroart.com/examples.htm

In AIP there is a measure tool to do this.

The big thing with gradient is they really mess up colour images, have a look at Roberts M27 with and without the gradients on the Gallery, you  will see what I mean.

Chris



P.S. who are the big 4?

Title: Re: Processing question for the Big Four!
Post by: Fay on Oct 11, 2007, 13:42:13
Thanks Chris,

Big 4 = you, John, Chris, Paul


Nothing to do with big game!

Fay
Title: Re: Processing question for the Big Four!
Post by: Fay on Oct 11, 2007, 13:51:08
Yes, Chris, that M27 is a good example.

Thanks
Title: Re: Processing question for the Big Four!
Post by: Rocket Pooch on Oct 11, 2007, 14:53:59
Who is the other Chris?
Title: Re: Processing question for the Big Four!
Post by: Fay on Oct 11, 2007, 14:55:37
Just testing, Space Dog, to see if you were alert, I meant Mike.



Fay
Title: Re: Processing question for the Big Four!
Post by: Mike on Oct 11, 2007, 16:58:15
Oooh i've not only got green stars now but i'm on eof the "Big Four". Cool !!  :)
Title: Re: Processing question for the Big Four!
Post by: Mike on Oct 11, 2007, 16:58:36
Hey what the heck !! Where have my green stars gone ?! Dammit !
Title: Re: Processing question for the Big Four!
Post by: Rick on Oct 11, 2007, 17:11:09
Your stars are green only in sections of the forum where you're a moderator. :)
Title: Re: Processing question for the Big Four!
Post by: JohnP on Oct 11, 2007, 17:21:59
Quick & easy way to see if there is a gradient is to use Threshold tool in PS..... Cheers,  John
Title: Re: Processing question for the Big Four!
Post by: Fay on Oct 11, 2007, 19:18:39
Slapped wrist from Rick there Mike.

Fay
Title: Re: Processing question for the Big Four!
Post by: Fay on Oct 11, 2007, 19:19:22
Thanks John I wil have a look
Title: Re: Processing question for the Big Four!
Post by: Rick on Oct 11, 2007, 19:34:20
Quote from: Fay on Oct 11, 2007, 19:18:39
Slapped wrist from Rick there Mike.
Mike is a moderator in some sections... just not this one (at the moment) ;)
Title: Re: Processing question for the Big Four!
Post by: Fay on Oct 11, 2007, 20:31:21
What does a moderator do, Rick?
Title: Re: Processing question for the Big Four!
Post by: Miriam on Oct 11, 2007, 21:15:20
I'm just joining in this conversation to see if I have managed to get a personal picture on the forum (although maybe I should have used the first picture I took of the moon.)

I'll have to try to get my webcam sorted to bring to Paul's on Saturday  - so much to learn . . . .
Title: Re: Processing question for the Big Four!
Post by: Rick on Oct 11, 2007, 23:42:56
Quote from: Fay on Oct 11, 2007, 20:31:21
What does a moderator do, Rick?
You may well ask... I couldn't possibly comment. ;)

(Though the temptation to slice-n-dice this thread and shuffle a whole bunch of pieces over into Chat is  quite strong...)
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