Re: [APML]: Reducing film grain

[Alfredo Zanazzo <alferd@mbox.lol.it>]

Jerry Lodriguss wrote:
> 
> 
> >As far as I know, photoshop does not have a function to register
> >different images of the same subject unless you use the free rotation
> >option that you can not control visually while you move the image.
> >You should get two identical prints using a register on the easel and
> >repeat the operation while scanning.
> 
> Alfredo, try this method in Photoshop v 3.05:
> 
> Copy one photo, and paste it as a layer into the other one, but select
> DIFFERENCE in the paste layer dialog box.  Click on the top layer in the
> Layers Pallette so that it is active and SELECT ALL.   Now you can rotate
> and move that layer (it has to be selected to rotate separately from the
> background layer) and its really easy to see when they are in register.
> 
> Open three windows on the same composite image, and zoom in on the left top
> corner of one, the center of another, and the lower right corner of the
> third.  When you move the top layer, you will see it move in all three windows.
> 
> Now get the stars in register in the exact center of the photo. Next use the
> ROTATE: ARBITRARY and experiment through trial and error until you get the
> corners in registration.
> 
> Then after they are registered, go to the Layers Pallette, and change the
> method that they are combined to MULTIPLY (or overlay... you get different
> histograms, multiply has a greater range of pixels on the histogram, but it
> depends on the original scan). Then FLATTEN the image to combine the two
> layers (flatten command is under the small right pointing arrow at the top
> right of the layers pallette).
> 
> Beware that LOTS of things can conspire to make two negatives not exactly
> the same, even though they were shot with the same instrument on the same
> night, such as focal length change due to temperature change, emulsion
> swelling due to high humidity, etc.  This can also be a problem with
> tri-color on techpan, you may even have slightly different focal lengths due
> to the different wavelengths of the filters (not totally sure how much
> difference this will make).
> 
> Jerry
> 
> email: jml@astropix.com
> Astrophotography Techniques and
> Digital Enhancement in Photoshop Tips:
> http://www.astropix.comTHIS IS A GOOD ANSWER!!!! tHANKS I will try and let you know the 
>results
I think that you must have been buisy for a while to load my M31....
-- 

--
Regards, Alfredo Zanazzo ( alferd@mbox.lol.it )

Professional home pages:   http://www.lol.it/aziende/music/zanazzo
Astronomy home page (Off/axis guider-camera project): 
http://www.lol.it/~alferd