[ANN] Image Filter Demo

Wilhelm Sanke sanke at hrz.uni-kassel.de
Fri Jun 23 17:24:54 EDT 2006


While I am still trying to bring my Image Filter Tool into a presentable 
format - I think I will need another two or three weeks before going 
public -  I  offer a preview  gallery that I have just uploaded to 
<http://www.sanke.org/MetaMedia>: Scroll down at the left until link 
"Image Filter Gallery" or go directly to 
<http://www.sanke.org/MetaMedia/ImageFilterGallery.htm>.

 Some of the applied filters are adapted from 3X3 to 9X9 matrix formats, 
others had to be scripted from scratch (like the Kuwahara filter) for 
Revolution, a number of created filters were transferred from my 
Colorpattern Toolkit and adapted to the handling of imagedata.

Filters greater than 3X3 or such filters that use additional factors 
(like the "bias" or "offset" values needed for instance to create 
reliefs) cannot be used with Derek Bump's or Chipp's Windows DLL, but 
all filters  - including the 3X3 format - can also be used without any 
external, meaning that they can be used on any platform with a number of 
"no-external" routines. I have now streamlined  the no-external scripts 
for applying the filters down to 7 seconds (2 GHz Windows computer) on 
the average. Many of the filters that do not apply matrices at all  can 
be much faster, up to less than 1 second.
 To reduce execution time from the original 90 seconds of the 
no-external script I started with, one of the steps was to abandon the 
intermediate use of arrays, another to take a number of computations out 
of loops.

The latest gain in speed occurred when I substituted
   " #  put binaryEncode("CCCC",255,tRed,tGreen,tBlue) after tconvData"
by
      "put numtochar(tRed) into char (ti + (tj+2)) of tconvdata
      put numtochar(tGreen) into char (ti + (tj+3)) of tconvdata
      put numtochar(tBlue) into char (ti + (tj+4) )of tconvdata".

This caused a speed gain of two seconds alone.

I may also be mentioned that many filters are slower - by 20 to 33 % - 
in the Revolution IDE compared to the Metacard IDE. Standalones show the 
same difference of speed.

There are also many filters not shown in the gallery  that make 
extensive use of mirroring, enlarging, decreasing, stretching, 
duplicating parts of images and many forms of color change.

I has been an interesting and educating exercise for me to gain some 
insights about filters mostly by intensive web searches.

I repeat my query for more and improved externals for faster filter 
handling. I very much doubt I could familiarize myself with the art of 
producing DLLs in the near future, so I hope for support from other list 
members or even from the Revolution crew.

Best regards,

Wilhelm Sanke




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