[Insight-users] Does data type has an influence on filter performance?

[Iván Macía]

Hi,

1) Absolutely, it is not the same to perform operations on double floating
point precision that with signed scalars. However, the input data, the
nature and complexity of the operations performed by the filter and the
desired precision will determine the pixel types to use and the difference
in speed. In this sense, one has to be extremely careful here not lose
information by wrong pixel choices.
2) The <short,short> should be faster, but in some cases not appropriate,
for example if the output is the result of a floating point calculation.
However, in some cases, the speed difference may be negligible compared to
other considerations such as memory. For example if you have to perform
morphological operations on a binary image and you choose the input and
output to be float, your memory consumption will be increased by a factor of
8, and in this case it does not make sense. If you perform Hessian based
calculations on an input image and you choose your output to be a tensor of
doubles instead of floats, you may run into memory problems, and probably
float will be enough for you.

Hope that helps

Iván

-----Mensaje original-----
De: insight-users-bounces at itk.org [mailto:insight-users-bounces at itk.org] En
nombre de Kishore Mosaliganti
Enviado el: miércoles, 28 de octubre de 2009 20:26
Para: Michael Xanadu
CC: insight-users at itk.org
Asunto: Re: [Insight-users] Does data type has an influence on filter
performance?

My 2 cents:

I think if you ensure same datatype for input and output, some ITK
filters are derived from InPlaceFilter and so this can reuse the input
memory. So, you will reduce the memory usage by 1/2.

Kishore

On Wed, Oct 28, 2009 at 12:51 PM, Michael Xanadu
<xanadu.michael at googlemail.com> wrote:
> Hi,
>
> 1. I wonder if the datatype I choose for a filter (e.g. signed short,
float,
> unsigned char etc.) does have an influence on the performance?
>
> 2. Does a filter, which has got a different input & output datattype,
> performs slower than a filter, in which I only use one datatype?
>
> // filter with different types...
> myfilter<short, float>
>
> // ...compared to a filter with same types. is this filter fasterr?
> myfilter<short, short>
>
>
>
> Regards, Michael
>
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