P3D Re: the value of keystoning

[Dylan The Hippy Wabbit <spacey@xxxxxxxxxxxxx>]

Dr T. quoted me, and commented:-

>>My method was to zoom in close, and use the status bar of my fave
>>graphics editor to read the pixel positions directly.  I figured that
>>keystoning would show up most where a foreground object approached the
>>four corners.

>I would say the "two edges", not four corners.  Keystone distortion has
>an axial symmetry:  It is zero in a vertical axis that passes from the
>center of the image and it increases as we move away from this axis.
>This makes the two edges the worse possible places for distortion.

Ah but if there is, say, 1% keystoning it is going to be easier to measure
if it nearly fills the height of the frame.  So you want something as tall
as possible as close to the edges as possible.  Hence the four corners.

Dave

______________________________________________________________________________

Walk tall, walk straight,
Spit the world right in the eye.

-Kevin Godley and Lol Creme


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