Radial blur filters

[AluminumStudios]

Can anyone explain the algorithm used in radial blur filters and why radial blur is so insanely slow to use!

I have an Athlon XP2200 with 512 megs of DDR333 RAM. When I use Radial blur on a video clip in Premiere or AfterEffects and render, I get like 1 frame/sec rendering rate. It's always been like. The strange thing is that my Athlon is about 5x faster than my old PIII system I used to use ... however it renders radial blur filters at about the same rate!

I'm guessing that by nature radial blur is a madly inefficient algorithm which may wind up in a lot of missed branch predictions which kills a CPU's efficiency ... but this is speculation.

I'm just curious to see what people will have to say about this ...

 

[Barnaby W. Füi]

Take a X by Y image, and then do Z amount of operations per pixel, and it's just gonna be slow. I don't think bad algorithms or branch prediction need to be an issue, some things are just intrinsically intensive and thus slow.

 

[notfred]

branch prediction is a function of the processor and has nothing to do with the radial blur algorithm that a programmer somewhere wrote. I've never written a radial blur filter, but even just resizing an image involves reading the values of 9 pixels for each pixel in the image, computing a weighted average of their colors, and then writing the output to a separate storage space. I'm sure a radial blur is reading data from MANY more than 9 pixels for each pixel it processes.

 

[AluminumStudios]

Take a X by Y image, and then do Z amount of operations per pixel, and it's just gonna be slow.

I've written C-code to do operations on images, but there is something about radial blur that makes it orders of magnitude slower than most other filters. I'm curious what that is. I"m curious what the algorithm is for it and why it executes so horribly slowly on modern CPUs ...

 

[Barnaby W. Füi]

Originally posted by: AluminumStudios

Take a X by Y image, and then do Z amount of operations per pixel, and it's just gonna be slow.

I've written C-code to do operations on images, but there is something about radial blur that makes it orders of magnitude slower than most other filters. I'm curious what that is. I"m curious what the algorithm is for it and why it executes so horribly slowly on modern CPUs ...

I just don't think it has anything to do with the processors it's running on. I imagine that it's slow because to do a radial blur you simply _have_ to do a lot of calculations for each pixel, and that takes time..

 

[SlowBo]

does anyone have any example of radial blur algorithm, implemented without any built-in functions? Can you help me please? pls pls