RE: Art Duplication [OT removing light fall off manually]
RE: Art Duplication [OT removing light fall off manually]
- Subject: RE: Art Duplication [OT removing light fall off manually]
- From: "Miles, Peter" <email@hidden>
- Date: Thu, 24 Sep 2015 20:04:46 +0000
- Thread-topic: Art Duplication [OT removing light fall off manually]
Thanks Ben! That's exactly the sort of feed back I was wanting.
The affinity Photo sounds very interesting. I'll look into that
Best regards
Peter
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Subject: Re: Art Duplication [OT removing light fall off manually]
On Sep 24, 2015, at 12:20 AM, "Miles, Peter" <email@hidden> wrote:
> by using using “linear Dodge (add)" on the folder that contains both these two layers, I can add these offset values to any image.
This is the obvious-but-incorrect operation. What you want instead is division, not addition...and, if you're not sure, do as I did to convince myself and spend some quality time futzing around with a spreadsheet.
Both addition and division will normalize the flat field image itself, but only division will recover the correct original values for arbitrary combinations of illumination falloff and subject reflectivity.
Photoshop does not offer a native division blend mode. It does, however, offer an invert-and-divide operator: Color Dodge. Layer the flat on top of the art. Invert the art. Set the blend mode of the flat to Color Dodge. And...Photoshop is notorious for being completely ignorant of gamma encoding; no matter what method you use, Photoshop is going to give you incorrect results unless your image is in a linear gamma 1.0 space.
Affinity Photo also lacks division but offers Color Dodge. But you can trivially set the blend gamma in Affinity Photo, making it vastly superior for color-critical work. And it beats the pants off Photoshop in lots of other ways, too. Its Wacom support doesn't feel quite as fluid as Photoshop's, but that's literally the only thing I can find where Photoshop still retains an edge...for everything else, Affinity Photo is at least as good, if not significantly better.
Cheers,
b&
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