Back to basics: Interpolation teaser

Hi, All,

Here is a question on interpolation and resampling.

I take two images (a white line in the middle of a dark background
image, dimensions 128x128 pixels; and a circle of radius 31 pixel
units centered on a dark background image, dimensions 128x128 pixels).

http://medicalimagingscience.googlegroups.com/web/Original_Line.jpg
http://medicalimagingscience.googlegroups.com/web/Original_Circle.jpg


Now I resample them to double the image size along each dimension
using an appropriate interpolation method.
Here are the results:

http://medicalimagingscience.googlegroups.com/web/Resampled_Line.jpg
http://medicalimagingscience.googlegroups.com/web/Resampled_Circle.jpg

My questions are:

- what can be inferred about the nature of the interpolation method
employed given only the above information?
- on the resample circle image, the circle profile displays some 'saw
tooth' patterns. Is that an artifact/limitation of interpolation
scheme? Or it is expected?
- if you think there are artifacts in the resampled images, what could
be a possible solution or a better way to resample?

This is NOT a home work assignment. It is part of some simple tests on
a library I have been running:-)

Thanks.

Pixel.To.Life.

.

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