Just in case, I am directing followups to p.o.t.

"Stephen Bell" <ste### [at] yahoocom> wrote :
>
> I don't understand.  I thought GIF was "lossless compression".  It
obviously
> compresses the file size, because a single frame GIF with the same color
> depth as a BMP of the same image is about a third of the size (I just
> checked).

    Well, .gif 'compresses' over .bmp but animations construct with no
further compression. They are almost the same size as that many .gifs in
separate files... unless you remove unneeded pixels.

> I don't understand what you mean by removing pixels... Please clarify.

    It is one of the most important things in making a compact gif
animation. Your first frame contains the entire image, but subsequent frames
only contain that portion of the image in which there are changes. So if
your switch only changed on the right half of the image, you would only need
to add half of each of the remaining files, IOW, just the right half...

    So if there were 10 frames of 10kb each and the uncropped animation
ended up as 100kb, removing half of 9 frames would leave you with about a
55kb animation with no loss of relevant information.

    In the top half of the following image you see an approximation of the
frames that might be used to construct a gif89a animation. The bottom half
represents the information that is contained in a reduced animation. Only a
rectangle containing the moving ball on the right in all of it's positions
is added to the background image in frame one, covering the first position
ball (and each subsequent position) with the following frame(s).

    If this doesn't explain it I will construct two gif animations to show
the difference. I think I still have the ulead animator somewhere... but
there are other programs that do this.

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