Slideshow possible?

[o0Julia0o]

Yes, nothing cuttet out with PreserveAspectRatio=1, but you get black borders.

[balala]

Yes, nothing cuttet out with PreserveAspectRatio=1, but you get black borders.

Depends on the aspect ratio of the image. If it has not the same aspect ration as the Image meter, then there is a part on the skin, which is not filled on by the image. But in such a case this part is transparent, not black, unless you're adding a SolidColor=0,0,0 option to the Image meter (in this case to the [MeterShowPicture] meter).
You have to decide what is best for you, if the shown image has another aspect ratio than the Image meter of the skin, if it is distorted or if you get a part which belongs to the skin, but it's transparent or black.