Re: [Gimp-user] Continuos Motion GIF from one Background Image

[Ofnuts <ofnuts laposte net>]

On 10/11/2013 07:18 PM, Jehan Pagès wrote:
> Hi,
>
>
> On Fri, Oct 11, 2013 at 6:15 PM, SevereIdaho <forums gimpusers com> wrote:
> > Hi there everyone.  I am looking to replicate an animation I found.  However, I
> > have no idea where to start.
> >
> > The concept is easy,  you have a picture of a supercell thunderstorm, and the
> > goal is to get the supercell to rotate in the animation and make it look like
> > its continuous motion.  Something that doesn't restart from the beginning.  It
> > basically looks like the storm is rotating and continuing to rotate without
> > restarting.
> Well I looked at the picture. That does not look continuous at all to
> me. :-) There are big jumps in the animation.
>
> My guess is that as typical internet users, we saw a lot of GIF, and
> don't have our expectation very high for animated gif. You know by
> experience that GIF quality is not high and your brain "expects" a
> shitty animation. But really imagine this same animation in a movie:
> you would never say it is a continuous rotation and you would wonder
> if this is a bad joke or very unskilled film-makers. :-)
>
> > I have an example, not sure who the author is, so I haven't been able to contact
> > him/her.  I am hoping this is something you can do with a script or at least
> > have a step by step instructions to replicate.
> The procedure to get continuous looking animations is that the last
> frame must be very close to the first frame, so that you could
> actually say the timeframe is a circle with no start nor end.
>
> In this specific image, the whole storm thingy is kind of fuzzy,
> clearly moving, but the general form of the storm is always more or
> less the same. So that is not perfect continuity, as I said, but close
> enough for your brain to accept the concept of continuity and fill in
> the missing pieces for it to be believable. :-)
>
> Technically in GIMP 2.8, frames are represented by layers. The bottom
> layer is the first frame, the top layer being the last. Once you have
> layers/frames that look ok, you can see a preview in Filters >
> Animation > Playback.
> Finally when it looks all good, you export as GIF, and when the GIF
> options dialog shows up, you check "As animation", and "Loop forever",
> the time between each frame, etc.
>
> And you are done.
>
> Jehan


To add to Jehans's anwer,if you have a sequence of shots, you can fade 
the end into the beginning to avoid a sharp transition:

+---+---+---+---+---+---+---+---+---+---+
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
+---+---+---+---+---+---+---+---+---+---+
                            +---+---+---+---+---+---+---+---+---+---+
                            | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
                            +---+---+---+---+---+---+---+---+---+---+
---------------------------------------------------------------------
             +---+---+---+---+---+---+---+
             | 3 | 4 | 5 | 6 | A | B | C |
             +---+---+---+---+---+---+---+

ImgA=75% Img7 + 25% Img0
ImgB=50% Img8 + 25% Img1
ImgC=25% Img9 + 25% Img2