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Re: Fractional Pixels Origin? [message #47637 is a reply to message #47549]

Fri, 17 February 2006 05:36

mmiller3
Messages: 81
Registered: January 2002

Member

>>>> > "David" == David Fanning <davidf@dfanning.com> writes:

> Then, JD Smith writes:

>> I'd urge those of you making the choice for your programs
>> to save the world confusion, and adopt the "natural"
>> choice: pixels centered on [a.5,b.5].

Here, here! JD - if you were running for office on that platform,
I'd vote for you!

> I'm not sure when (if ever) I am going to *use* fractional
> pixels, but I would like to understand it. :-)

I used to feel the same way, but then I started working on
multimodality medical image registration. In nut shell, I create
registration transformations for each image from pixel
cooridinates to space coordinates. When I want any image
intensity at any point in space, I use the inverse transforms to
take my space coordinates to pixel coordinates and then
interpolate the original data at those pixel coordinates. If I
use integer pixel coordinates, I natually get nearest neighbor
interpolation. If I want to use some other interpolation method,
I need to use fractional pixel coordinates.

Now my main problem is that every time I see a discussion like
this, I have an anxiety attack about whether or not my code
consistently does what I think it does!

Mike

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[Message index]

		Re: Fractional Pixels Origin? By: David Fanning on Thu, 16 February 2006 21:15
		Re: Fractional Pixels Origin? By: Greg Hennessy on Thu, 16 February 2006 20:20
		Re: Fractional Pixels Origin? By: David Fanning on Thu, 16 February 2006 16:02
		Re: Fractional Pixels Origin? By: JD Smith on Thu, 16 February 2006 14:48
		Re: Fractional Pixels Origin? By: rm on Thu, 16 February 2006 06:24
		Re: Fractional Pixels Origin? By: Craig Markwardt on Wed, 15 February 2006 14:28
		Re: Fractional Pixels Origin? By: Wayne Landsman on Wed, 15 February 2006 13:31
		Re: Fractional Pixels Origin? By: David Fanning on Wed, 15 February 2006 13:03
		Re: Fractional Pixels Origin? By: JD Smith on Fri, 17 February 2006 13:25
		Re: Fractional Pixels Origin? By: mmiller3 on Fri, 17 February 2006 05:36
		Re: Fractional Pixels Origin? By: Greg Hennessy on Fri, 17 February 2006 05:06
		Re: Fractional Pixels Origin? By: Wayne Landsman on Thu, 16 February 2006 23:50

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