[IPOL discuss] computing and displaying contours

Wed Mar 16 11:47:19 CET 2011

> Seriously, SVG has real advantages over EPS: more drawing primitives,
> the support of "filters" (blurring, convolutions, ...) and direct
> inclusion in (X)HTML documents. Maybe PostScipt is more exciting for
> programmers because it's a stack-oriented programming language... but
> these considerations are not relevant for IPOL :)
>
> Rafael chose eps because of the bad visual quality of svg-png
> conversion. I think it's worth a benchmark, vith visual comparisons.

There is another advantage of EPS: it can easily be converted to PDF
(Ghostscript can do it, and there are other tools).  Many Windows
users have the Adobe Reader browser plugin installed, so they can view
the PDF directly in the browser.

Pascal

On Wed, Mar 16, 2011 at 11:20, Pascal Monasse <monasse at imagine.enpc.fr> wrote:
> Hi Jose-Luis,
> I do not have time right now to look at your code, but you can still send it
> to me.
> Best,
> Pascal
>
> On Wednesday, March 16, 2011 11:03:14 am José Luis Lisani wrote:
>> Hi Pascal,
>>
>> I think I will have some time to work on the code and demo in 2 weeks.
>> In fact, the code is written, I just have to clean it up
>> and come up with a online demo.
>> If you want to take a look at the code I can send it to you right now.
>>
>> Best,
>> José Luis
>>
>> El 16/03/2011 9:48, Pascal Monasse escribió:
>> > Hi Jose Luis,
>> > Yes, this was also on my todo list when I get some available time (in 10
>> > days). If you have some code for that, it would help jumpstart the
>> > project. This would be an IPOL submission by itself, and it would also
>> > be used in the image curvature microscope.
>> > Best,
>> > Pascal
>> >
>> > On Tuesday, March 15, 2011 06:18:09 pm Jean-Michel Morel wrote:
>> >> José Luis,
>> >>
>> >> This sounds great. Pascal Monasse and Adina Ciomaga also need it
>> >> "urgently".
>> >>
>> >> Best,
>> >> JM
>> >>
>> >> José Luis Lisani a écrit :
>> >>> Dear all,
>> >>>
>> >>> I have a C++ code for computing and drawing level lines from a
>> >>> bilinearly interpolated
>> >>> version of the image:
>> >>> http://www.cmla.ens-cachan.fr/fileadmin/Documentation/Prepublications/2
>> >>> 00 1/CMLA2001-16.ps.gz
>> >>>
>> >>>
>> >>> I had planned to publish the code at IPOL, on an undefined date.
>> >>> But, if there is a real need for the code I can accelerate my plans. I
>> >>> think I can
>> >>> have something running in a month or so.
>> >>> Once the code has been certified by IPOL it could become part of the
>> >>> tools made available to the rest of authors.
>> >>>
>> >>> Best regards,
>> >>> José Luis
>> >>>
>> >>> El 15/03/2011 17:38, Juan Cardelino escribió:
>> >>>> Dear all,
>> >>>>
>> >>>>             I remember that we discussed the topic of visualization in
>> >>>>
>> >>>> the september meeting. I'm not sure if you have advanced in that
>> >>>> direction in January, if that's the case, please update me.
>> >>>> So far I contributed in demos for me and for people that were also in
>> >>>> IPOL. I'm facing the first case of helping a non-member of the crew,
>> >>>> and I have some doubts about were to draw the line of what's
>> >>>> responsibility of the author and what's the task of the editor.
>> >>>>
>> >>>> The case is the following: the author is Mauricio Delbracio and his
>> >>>> algorithm that estimates a PSF, so the output are regular samples of a
>> >>>> 2D function. When thinking about visualization, the wanted to display
>> >>>> the level lines of that function. This involves a couple of tasks:
>> >>>>
>> >>>> 1) actually computing the contours:
>> >>>> a) I think this should be done by the author
>> >>>> b) however, it won't hurt to have a handful of simple functions at
>> >>>> hand, to provide the authors. Maybe we can just reuse the code done by
>> >>>> the first autor interested in doing the task.
>> >>>> c) I think about many cases in which we could be interested in
>> >>>> computing/showing level lines, so maybe the definition of an interface
>> >>>> (how to specify the points of the contour) could be useful.
>> >>>> d) I google'd for a bit to find any clean C implementation of the
>> >>>> marching squares algorithm but without luck. do you know/have any
>> >>>> piece of C code to compute contours? I know implementations in ITK and
>> >>>> VTK, but that's out of the question. I find sad that there is no
>> >>>> reference implementation of such well-know and established algorithms.
>> >>>>
>> >>>> 2) drawing the contours on the web page:
>> >>>> a) the first ugly way to do this is to just ask the author for an
>> >>>> image with white pixels over a black background. I think this is
>> >>>> efortless but poses many problems (low resolution, no scaling, etc).
>> >>>> b) Ask the user to draw in a vectorial format like eps or svg. As far
>> >>>> as I know, svg support varies too much across browsers. (correct me
>> >>>> please if I'm wrong)
>> >>>> c) ask the author for a description of the curve as in 1c) and render
>> >>>> it using javascript of whatever we like. Here we need a precise
>> >>>> definition of the curve, as I guess we don't want to recode that part
>> >>>> for each new demo.
>> >>>> d) I think in general this should be our concern, not the authors.
>> >>>>
>> >>>> Personally, I would go for the svg, but sadly technology is not on our
>> >>>> side yet.
>> >>>> What do you think? Is there any hack to make an svg look the same in
>> >>>> different browsers?
>> >>>>
>> >>>> Thanks in advance.
>> >>>> Best regards,
>> >>>>
>> >>>>                     Juan
>> >>>>
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