Re: Core Image in FxPlug example
Re: Core Image in FxPlug example
- Subject: Re: Core Image in FxPlug example
- From: Darrin Cardani <email@hidden>
- Date: Tue, 28 Apr 2009 09:01:24 -0700
Glad it helps! It looks to me like Displacement Distortion is using
the magnitude and direction of edges in the map image to offset pixels
in the source image. I believe it first converts the map image to
grayscale, then finds the difference of each pixel with its neighbors
in the x and y directions. It multiplies the x and y differences by
the scale parameter and uses the resulting vector as an offset from
the current pixel in the source image.
So let's say the grayscale version of your map image looked like this:
0.75 0.89
0.23 0.52
It takes (0.75 - 0.89) = -0.14 as the x offset
It takes (0.75 - 0.23) = .52 as the y offset
It then multiplies those values by the scale parameter. Let's say it's
set to 25, so it comes up with an offset of (-3.5, 13). It adds that
to the current (x,y) coordinate and samples the input image at (x -
3.5, y + 13).
Does that make sense?
Darrin
On Apr 27, 2009, at 5:53 PM, Patrick Sheffield wrote:
Thank you Darrin - this helps a lot.
I wonder if you could shed some light on a specific CoreImage filter
- specifically DisplacementDistortion...
In Shake and in FxScript, the X-Displacement is governed by one
channel in the displace image and the Y-Displacement by another. I
can't find any documentation on the CI filter as to how it handles
this.
Thanks,
Patrick
--
Darrin Cardani
email@hidden
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