BUG: matrix interpolation doesn't work properly
Bug report: Under certain circumstances (one in particular), a
jit.matrix will not interpolate properly.
Max/jitter 4.5.7/1.5.2
OS X 10.4.6
Expected behavior:
When trying to interpolate to a single dimension (e.g. a 1xN matrix),
I expect the result to be a single-column matrix with each cell of
the column containing an average of the entire row it belongs to.
Observed behavior:
When trying to interpolate to a single dimension (e.g. a 1xN matrix),
the result is not an interpolated matrix but rather the 1st column of
the original matrix with no interpolation.
Example patch:
(Read in a movie or image, and observe the results. You should
notice that the jit.submatrix output is conspicuously identical to
the jit.matrix output)
Best,
Evan
Oops, the jit.submatrix should be @dim 1 240, NOT @dim 1 512. But
the result is the same, no need to change it, I just didn't want to
confuse anyone. (Sorry, copied and pasted out of another patch).
Best,
Evan
>
> Expected behavior:
> When trying to interpolate to a single dimension (e.g. a 1xN
> matrix), I expect the result to be a single-column matrix with each
> cell of the column containing an average of the entire row it
> belongs to.
>
> Observed behavior:
> When trying to interpolate to a single dimension (e.g. a 1xN
> matrix), the result is not an interpolated matrix but rather the
> 1st column of the original matrix with no interpolation.
This is not a bug. This is how pointwise linear interpolation works.
It is not an averaging filter. For more on the subject, I'd suggest
searching online.
If you want to average all elements in a column/row, etc, I would
suggest you iterate, downsampling by two and averaging each time.
Below is an example, but it only works exactly right for power of two
matrices.
-Joshua
Sorry, I misunderstood what the effects of interpolation would
actually be - sometimes you don't realize that you have the wrong
impression of something until you've actually tried to code it...
Thanks for the example patch, it's very helpful.
Best,
Evan