"Blurred vision" of Rev newsletter, Apr 21

[Alejandro Tejada]

Hi Wilhelm,

on Tue, 26 Apr 2011
Wilhelm Sanke wrote:

> Hanson presents a series of scripts that are related to each other to
> achieve a "blur filter" effect using sort of a 3x3-convolve matrix. I
> want to add some information and discuss the issue in a somewhat broader
> context. As Hanson did not himself supply a sample stack, I produced one
> that contains his scripts along with a number of alternative "blur"
> scripts and apart from that added some other filters which might be
> interesting for Livecode users that intend to look at image processing.
>
> You can get the stack here:
> <http://www.sanke.org/Software/BlurredVision.zip>.

Many Thanks!! :-)

> To be able to use the convolve matrix with larger images, I made a
> number of changes to Chipp's original script,
>  abandoning among other things the use of arrays in this context or the
> "round" function which speeded up
>  the performance of the filter by a factor of 10.8,

snip

> This raises the question why Hanson's scripts are so much slower - 12
> times - than "matrix blur 3x3"? I did not yet find time for a detailed
> analysis, but I believe that  - even given the special structue of the
> related scripts - the performance could certainly be improved. One
> recommendation would be *not* to use arrays , which against popular
> belief really "slows down" performance in this context of image processing.

Oh well, this explain why a bezier function that uses arrays
(in an older version of my "Import Vector graphics" stack )
was slower than other two arrayless functions.

Ideally, your post, Wilhelm, should be archived in a more visible place,
like the Livecode Lessons or as a "Sticky" message in the Forum.

Al