fish eye effect


im looking for fish eye effect (sometimes called bulls eye effect or just wide angle effect).

is there any way to achieve that effect in kdenlive?

There is a frei0r based filter that appears in Kdenlive as Lens Correction that might achieve what you are after.

I am working on a Frei0r plugin that will do that, in a more "scientific" way, based on the math functions used in fisheye design.

Actually, I have written the code a few years ago for "defishing", but it can do "fishing" too.

I had written it then for separate color planes, but frei0r uses packed color, so I need to work a bit on it. Should be ready in a few weeks.

BTW, wanted to join the Frei0r developers mailing list to discuss some things, but my Firefox goes up in panic about suspicious certificates etc. Anybody here who went through that?

OK, here it is:

A "readme" file is included with further explanations.
As far I could test it, it seems to work OK, if a bit slow with
high-definition video. (but does SD in realtime without problems)

works really great!

maybe you could add a zoom parameter to avoid a second plugin just to fill black spaces.

good job! :)


A zoom type option is already included: there are three autoscale options, and manual scale. One of the scaling options is to auto set the scale to just eliminate the blank areas.

Try adjusting the "Scaling" parameter. If you set it to max (751...1000), you can also adjust the zoom manually from 1/100 to 100X with the "Manual Scale" slider.

Let me know if scaling does not work on your machine, because then it is a bug and I must fix it!

range numbers for settings is confusing.

i know there are limitations on plugins interface, but i've seen some using just the exact number of steps when the atribute has few options.

for example:

1 = normal
2 = high
3 = low

instead of

1-333 = normal
334-666 = high
667-1000 = low

I was thinking about doing it this way (would be very easy to do it, no problem there...)

However, I wasn't sure if this would work in other host applications that can use Frei0r plugins.

Namely, the Frei0r parameter itself is a floating value between zero and one.

Kdenlive maps this to integer range 0...1000, but do all host applications do the same?
I just don't know.

For example, if another application uses 0...100, setting "2" there would be equivalent to setting "20" in kdenlive.
That is, 2 in Kdenlive translates into 0.002 for the plugin, but in an hypothetical host application with 0...100 sliders, setting "2" would translate into 0.02!

I asked about this on the Frei0r mailing list, but got no answer...

Any suggestion? Or experience with other Frei0r-using host applications?

not really, i just told you what i saw on other plugins.

I have just installed the "Open Movie Editor" to see how it handles Frei0r parameters.

It has only sliders with no numerical value displayed or input. So I guess something other than the "divide in equal subranges" would be even harder on the user in this case.

Actually playing with this, I found out that it is quite easy, if one does not think about number ranges, but just sets the slider to "third quarter" or whatever, visually. The problem is of course, one needs to know the number of choices...

It's a pity that the Frei0r interface only supports float and boolean parameters. Actually I was thinking about using interacting booleans in a radio-button style. Decided against, because I think it would eat too much of the GUI screen area.

BTW I noticed something strange: I assign some defaults in the constructor function, but in Kdenlive the sliders all come up at zero???
I thought it was a bug of mine, but now I see that in Open Movie Editor, they come up with the defaults that I set in constructor.

I found a way to make the "multiple choice" parameters more user friendly in Kdenlive.

You need to put an XML description of the plugin in


(might be different on your system...

I have attached the XML file for Defish0r.

This way, the defish0r.c code stays the same (0...1 range) for compatibility with other host programs, but in Kdenlive, the multichoice parrameters are now 1..N as suggested.

NOTE: I hadd to add _.txt, otherwise the forum engine did not allow me to attach it. Just remove this, the filename must end in .xml