RE: [APML] Matt, Jeff, Chris, Jerry and stuff like dat dere

[Jerry Lodriguss <jml@astropix.com>]

>To stack, convert each to a negative again and multiply.


Chris,  you can save yourself a step here, you don't need to convert to a 
negative and multiply, you can just use screen on the two original positives.

In Picture Window, "subtractive filter" is the same as screen in Photoshop.

Note that both multiply and screen are non-linear combination methods. 
Shadow area brightness and contrast are boosted, but at the cost of 
contrast and tonal separation in the highlights.


Jerry


Astronomical photography: http://www.astropix.com




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