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Why are different results obtained when zoom applied via different methods?

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Michael Leibson
Why are different results obtained when zoom applied via different methods?
on Nov 29, 2017 at 3:24:48 pm

I’m completely new to video and video editing, and need help with what I’m assuming is a basic issue, please.

Instructions for the ‘pan and zoom’ of an effects app I’m trying out seem to have two modes of application: (1) the effect can be applied directly to a clip or image, or, (2) it can be applied to a track to which one should first “add a project-sized clip or solid to the timeline”, and then link the effect to the clip or image as an external file.

I’m using a still image rather than a clip, and have experimented with both methods – but I get different results in each case, and I am trying to understand what’s at play.

The project was set to use the source material’s aspect ratio.
The image is 4,000 x 3,000, and I chose a solid white, via the video editor’s ‘media generator’, for that “project-sized solid”.

In approach (2), I noticed that the ‘solid white’ had a frame size of 352 X 240, and that, indeed, the project’s aspect ratio was 352 X 240. The still image, used as that “external file” had its original 4,000 x 3,000 dimensions. For the very beginning of the clip (of a pan across this still image), I chose a zoom of 480%. The resulting image was very clear and focused – nice and sharp.

As an experiment, I then applied the effect, on a different track, using approach (1). There, too, I set the opening zoom to the same dimension. However, the resulting image there was unclear, and very poorly focused.

I’m trying to understand why, in this same project, the two approaches produced such different results. It would seem that, in approach (2), I am applying a zoom to a large image that is somehow being forced into a small (352 x 240) frame. (Does this perhaps result in a much more dense – and therefore finer – resolution?) In approach (1), I seem to be applying the same zoom to that large image in its original size – yet the aspect ratio for the project is still set to the smaller size.

I’ve spent hours trying to figure this out, so I’d really welcome any enlightening feedback!

Thanks, in advance, for any perspective (no pun intended) you care to share!


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peter mcauley
Re: Why are different results obtained when zoom applied via different methods?
on Dec 4, 2017 at 9:11:03 pm

The results are dependant on where the filter gets the image from. The best results are when the filter pulls the clip directly from the desktop instead of passing through the host transform matrix prior to arriving in the filter's own transform matrix.



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Michael Leibson
Re: Why are different results obtained when zoom applied via different methods?
on Dec 8, 2017 at 11:41:09 am

Thank-you, Peter!


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