We could probably borrow some tools from R http://vincebuffalo.org/2012/11/14/learn-visualization.html makes some interesting suggestions.
I particularly liked "color brewer" - I think that that concept could fit well into j's plot. -- Raul On Thu, Apr 25, 2013 at 8:45 AM, Sarah Arnold <[email protected]> wrote: > Many thanks to everybody for your input! J'ers seem to be very well > supported... > > > On 04/25/2013 11:17 AM, Cliff Reiter wrote: >> >> Hi Bob et al, >> In J there is a wonderful conjunction that allows you to apply any >> function to all sorts of tessellations of the data. I used u;._3 apparently. >> I think Sharp APL had a similar thing but I don't know if that is available >> in your compiler. >> >> FVJ3 version is >> >> medianf=: 1 : 0 >> (2#m)"_ (<.-:*:m)&{@:(/:~)@,;._3 ] >> ) >> >> where >> >> 13 medianf g >> >> would apply a 13 by 13 median filter on g. The whole thing is a fork. >> (<.-:*:m)&{@:(/:~)@, ravels the patch, orders the data and takes a datum >> from the middle (lower choice if even size). >> ;._3 distributes to tessellations. ] is the identity (g) and (2#m)"_ gives >> 13 13, the desired size of the tessellation. Very substantial speed ups are >> available for multiplicative filters using moving windows (\ as dyad), but >> median isn't. >> Best, Cliff >> >> On 4/24/2013 2:10 PM, Robert Bernecky wrote: >>> >>> Hi, Cliff, >>> >>> I'm looking to turn your medianf function into APL, but >>> will have to relearn J in order to do so. Can you give me a >>> quick translation into APLish of that? If that's not trivial, >>> or if you're up to your butt in alligators, it's no big deal: >>> I'll dig out the J books and figure it out. >>> >>> What I want to do is to compile the APL code into >>> SAC, then compile that and see how well it works in >>> both serial and parallel environments. >>> >>> Thanks, >>> Bob >>> >>> On 13-04-24 11:01 AM, Cliff Reiter wrote: >>>> >>>> In addition to my visualization book (OK fractals) you might look at >>>> preprints of APL quote quad articles >>>> http://webbox.lafayette.edu/~reiterc/j/withj/withj12_im_proc01_pp.pdf >>>> http://webbox.lafayette.edu/~reiterc/j/withj/withj14_im_proc02_pp.pdf >>>> and the vector paper >>>> http://archive.vector.org.uk/art10500860 >>>> and ask the forum (or me) if you have questions -- I tend to always be a >>>> couple days out of date on the forum, but I do browse it. >>>> Those books and articles are best used with J6 but I hope that in a >>>> semester or two I will transition to J8. >>>> Best, Cliff >>>> >>>> On 4/24/2013 10:32 AM, Sarah Arnold wrote: >>>>> >>>>> Hi Ben >>>>> >>>>> Yes, in mathematica it takes approximately 2 minutes to do the 13x13 >>>>> medianfilter for a 2004 x 2006 picture... I usually use much bigger >>>>> boxsizes >>>>> (about 120x120), so I can pick up a coffee while the program is running. >>>>> >>>>> What you write about your use of J sounds promising to me. I ordered >>>>> the book from Reiter in the library and will have a look at it. The >>>>> tutorials you mentioned: are they somehow available? >>>>> >>>>> Thanks a lot for your answers! >>>>> >>>>> On 04/24/2013 04:14 PM, Ben Gorte - CITG wrote: >>>>>> >>>>>> By the way, Cliff Reiter's median in J isn't slow at all, for example >>>>>> compared to famous software like ImageMagick: >>>>>> >>>>>> $ time convert -median 3x3 p19.pgm m3.pgm >>>>>> >>>>>> real 0m11.961s >>>>>> user 0m22.333s >>>>>> sys 0m0.292s >>>>>> $ >>>>>> $ time convert -median 13x13 p19.pgm m13.pgm >>>>>> >>>>>> real 1m13.204s >>>>>> user 2m22.517s >>>>>> sys 0m0.352s >>>>>> >>>>>> Good old xv uses 10s resp. 5 minutes. >>>>>> >>>>>> Ben >>>>>> >>>>>> ________________________________________ >>>>>> From: [email protected] >>>>>> [[email protected]] on behalf of Ben Gorte - CITG >>>>>> [[email protected]] >>>>>> Sent: Wednesday, April 24, 2013 15:47 >>>>>> To: [email protected] >>>>>> Subject: Re: [Jchat] J for Image Processing >>>>>> >>>>>> 6!:2 'med3 =: 3 medianf p19' >>>>>> 17.9526 >>>>>> 6!:2 'med13 =: 13 medianf p19' >>>>>> 47.2474 >>>>>> $p19 >>>>>> 3072 4608 >>>>>> >>>>>> (A median 3x3 median filter on a 3072x4608 image takes 18s, and a >>>>>> 13x13 median takes 47s). >>>>>> >>>>>> This is on an Intel Core 2 Duo CPU at 2.00GHz , using the median >>>>>> function from the already-mentioned book of Cliff Reiter "Fractals, >>>>>> Visualization and J": >>>>>> >>>>>> medianf =: 1 : '(2#m) "_ (<.-:*:m)&{@:(/:~)@,;._3 ]' >>>>>> >>>>>> I have a C program doing the same in 0.7s resp. 1.2s, but when I >>>>>> consider how much time it took me to write that one, I must compute an >>>>>> awful >>>>>> lot of medians with it before earning back that time. >>>>>> >>>>>> Ben >>>>>> ________________________________________ >>>>>> From: [email protected] >>>>>> [[email protected]] on behalf of Sarah Arnold >>>>>> [[email protected]] >>>>>> Sent: Wednesday, April 24, 2013 15:02 >>>>>> To: [email protected] >>>>>> Subject: Re: [Jchat] J for Image Processing >>>>>> >>>>>> Hi >>>>>> I should have been a bit more precise: I'm into astronomy. I'm mostly >>>>>> interested in noise reduction / signal enhancement and therefore apply >>>>>> different filters to the image. Some of this operations, like for >>>>>> example the MedianFilter[] function, take a lot of computation time. >>>>>> >>>>>> ---------------------------------------------------------------------- >>>>>> For information about J forums see http://www.jsoftware.com/forums.htm >>>>>> ---------------------------------------------------------------------- >>>>>> For information about J forums see http://www.jsoftware.com/forums.htm >>>>> >>>>> >>>>> ---------------------------------------------------------------------- >>>>> For information about J forums see http://www.jsoftware.com/forums.htm >>>>> >>>> >>> >>> ---------------------------------------------------------------------- >>> For information about J forums see http://www.jsoftware.com/forums.htm >>> >> > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
