On 08/30/12 06:11, scl wrote:

Hi,

I'm currently working out a GUI brainstorm idea for the Gaussian and Tileable Blur dialogs. Both dialogs let the user choose between the algorithms IIR and RLE. The documentation says, IIR is faster on photographs, RLE faster on drawings. I've never found a difference in computing time between these both algorithms and wondered, whether the choice is still necessary with modern computer environments. What do you think about it?

Thank you,

Sven _____________

It would probably be useful if the doc was clearer about what ti meant by "drawings". It makes sense that RLE would be faster in block graphics where there are large areas with exactly the same colour value.

If the user is "drawing" with rounded brushes with faded edges and softening things with gaussian blurs the drawing will not necessarily fit the criteria where RLE is faster.

"With modern computers" argument is countered by "on modern images". As the hardware gets faster the images also get bigger ( in both x and y) . As gimp progresses to higher bit resolutions any difference may become more relevant not less.

I'd suggest some timings on large photo and similar sized image half black, half white (extreme example of the block graphic case).

I'm also wondering about the IIR label. I have not dug out the code but I was not aware that gaussian could be mode by IIR filter, isn't it rather a kernel ie FIR method?

If it is IIR I should have a look , it may be useful in something else I'm doing.
OK, a quick google reveals I'm correct, the IIR method is just an approximate method that makes the computation complexity independent of sigma. By corollary the approximation must get worse for larger blur radius. Though I don't know whether the eye will detect which is the "better", purer blur.

So IIR label is fine.

/gg .

On 30 August 2012 01:11, scl wrote:

Hi,

I'm currently working out a GUI brainstorm idea for the Gaussian and Tileable Blur dialogs. Both dialogs let the user choose between the algorithms IIR and RLE. The documentation says, IIR is faster on photographs, RLE faster on drawings. I've never found a difference in computing time between these both algorithms and wondered, whether the choice is still necessary with modern computer environments. What do you think about it?

Sven,

You are correct in the sense that some filter choices are obsolete. Most filters had not been touched in a while - and there is the compromise that at least the inner working (i.e. the API calls) stay the same throughout GIMP 2.x.
However, most filters are part of the overhaul taking place in the development version of GIMP. In the case of the more used Gaussian Bluer, the work is already done, and the filter works interactively, with on-canvas live preview, just like any GIMP tool, and the algorithm selection option is gone.

If you are willing to make suggestions and help improving GIMP, you are highly encouraged to have one copy of the development version working, so that you can poke around.

js ->

Thank you,

Sven
___

On Thu, 2012-08-30 at 11:49 +0200, gg wrote:

"With modern computers" argument is countered by "on modern images". As the hardware gets faster the images also get bigger ( in both x and y) . As gimp progresses to higher bit resolutions any difference may become more relevant not less.

I just compared the two methods and found RLE tool about 10 or 11 seconds and IIR took maybe 19 seconds on the same image with the same radius (2.5p I think).

Liam

On 31 August 2012 22:11, Liam R E Quin wrote:

On Thu, 2012-08-30 at 11:49 +0200, gg wrote:

"With modern computers" argument is countered by "on modern images". As the hardware gets faster the images also get bigger ( in both x and y) . As gimp progresses to higher bit resolutions any difference may become more relevant not less.

I just compared the two methods and found RLE tool about 10 or 11 seconds and IIR took maybe 19 seconds on the same image with the same radius (2.5p I think).

So, maybe the disctinction will be still necessary when GIMP 2.10 is out -- however, the existing Gaussian blur GEGL plug-in does not offer any choice in algorithm

js
->

Liam

--
Liam Quin - XML Activity Lead, W3C, http://www.w3.org/People/Quin/ Pictures from old books: http://fromoldbooks.org/ Ankh: irc.sorcery.net irc.gnome.org freenode/#xml Co-author, 5th editoin of "Beginning XML", Wrox, July 2012

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So, maybe the disctinction will be still necessary when GIMP 2.10 is out -- however, the existing Gaussian blur GEGL plug-in does not offer any choice in algorithm

A choice in algorithm is however made internally. The choice depends on the radius of the blur.