Legacy ImageMagick Discussions Archive

With regard to some latter posts regarding timing of -fx within viewtopic.php?f=2&t=11601&hilit=fx

I did some tests with command line IM 6.4.2-1 Q16 (non-hdri) and found that indeed -fx is an order of magnitude slower when variable names are more than 2 characters long. I think this is something that needs to be fixed for IM 7 if this is not a bug and can be fixed sooner.

Here are my tests in generating a radial gradient using rad=64

2 characters => 1.66 sec
time convert -size ${rad}x${rad} xc: -monitor \
-fx "xx=i-w/2; yy=j-h/2; rr=hypot(xx,yy); 2*rr/$rad" radius_rr.png

3 characters => 42 sec
time convert -size ${rad}x${rad} xc: -monitor \
-fx "xxx=i-w/2; yyy=j-h/2; rrr=hypot(xxx,yyy); 2*rrr/$rad" radius_rrr.png

4 characters => 42 sec
time convert -size ${rad}x${rad} xc: -monitor \
-fx "xxxx=i-w/2; yyyy=j-h/2; rrrr=hypot(xxxx,yyyy); 2*rrrr/$rad" radius_rrrr.png

10 characters => 43 sec
time convert -size ${rad}x${rad} xc: -monitor \
-fx "xxxxxxxxxx=i-w/2; yyyyyyyyyy=j-h/2; rrrrrrrrrr=hypot(xxxxxxxxxx,yyyyyyyyyy); 2*rrrrrrrrrr/$rad" radius_rrrrrrrrrr.png

Any chance this can be fixed.

I also want to point out that -fx does not allow alphanumeric characters, only alphabetic characters. Having a second numeral following an alphabetic character would allow some better loop scripting to set up variables for -fx.

Another feature that would be handy would be to allow -fx to access unix array elements. I tried this and it does not work.

Thanks for consideration of these enhancements.

Fred

There is a patch for the problem you posted in the ImageMagick subversion trunk.

Thanks

Does the patch include a fix for alphanumeric characters as well as the speed issue? or only the latter?

The speed issue is a bug, the alphanumeric request is an enhancement. Enhancements are a lower priority. Its on our list of things to do with no current ETA.