"Kenneth" <kdw### [at] earthlinknet> wrote:

> ...Test #2 was re-rendered a 8-times the original--5760 x 4320--and NOT blown
> up in P.Shop. (Although I *have* included a blown-up close-up of that.) Again,
> it looks like a full-pixel shift.

Sorry, I was mistaken about that; it *is* a 1/2-pixel-shift, in the context of
what is meant here. (I got confused about what '1 pixel vs. 1/2 pixel' meant.)

For Clipka:
Something else that occurs me to me about my posted image tests (something
obvious, and you probably realized this already) is that the 1/2 shift during
interpolation is a shift *based on the original pixels of the image_map* (NOT a
1/2 shift in the pixels of the *re-rendered* image of the image_map.) To help
explain that more clearly: My 720 X 540 test chart with its single-pixel-lines,
when re-rendered at 8X its size, creates 8-pixel-wide lines; that's perfectly
understandable. But when interpolated, it creates an 8-pixel shift to the left
and down (i.e., not 1/2 or 1 pixel as I would have expected.)  With the
interpolate 'blur' filling an area of 16 pixels--twice the width of the 8-pixel
line. I wonder if this behavior makes sense?  Don't know; I would have expected
far less blur and far less 'movement' in such a case.

What this seems to mean is that the shift that we currently see (and the
'amount' of interpolation) is based on the magnification factor when
re-rendering the image_map's pixels. For example, say the image_map is on a box
that's deep into z, so that it re-renders at a fraction of its real size. (Which
is usually the case.) In such a case, the re-rendered shift would be far less
than 1/2 pixel, to my mind. Which I *guess* is a good thing(?)

I don't quite know what to make of this; but I thought I'd mention it. It may
have a bearing on how you figure out your corrections.

Ken

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