Scaling filter effect

I am very happy with KDEnlive (especially with the improved stabilty)

I just wanted to point out a filter which could use some improvement.

The scaling filter

Thank you


Is this the scale and tilt filter? Have you tried pan and zoom. It might work better.

Is this the scale and tilt filter? Have you tried pan and zoom. It might work better.

I use the "move and zoom" filter from Charles Yates

There is quite some jumping at the edge of the picture.
especially on the right edge of the picture.

Small text is rendered badly when moving.

The problem you have is aliasing of the higher spatial frequencies in the picture. Sharp edges have high frequency content, and small text is hardly anything but high frequencies - so if you want to bring out aliasing problems, small text is what you need! To get perfect results on small text, you would need a sophisticated resampler, like Lanczos with a steep lowpass response - but that is very S-L-O-W, useful for single images, less so for video.

Luckily "natural" images tend to have much less high frequency components, so one can get away with simpler resampling algorithms.

If you can't avoid small text, maybe a slight blur before rescaling will help a bit.

There we meet again :D
I had the same trouble (see, so using pan&zoom doesn't help. Also, there are quite some natural images that provide tons of high frequency: Tree leaves, grass etc.
Yes, a more sophisticated interpolator would be a great thing - even if it's slow.

For panning of images I now pre-scale the image to the desired dimension and then try to get the panning only do integer-steps. This obviously doesn't help for zoom...

You can try different interpolators in the "corners" effect, should be possible to set the corners to get a pure zoom or pan.

I'm not sure for big zoom down ratios, as there is no additional pre-filtering in "corners".

P.S grass etc, being mostly random, is much less of a problem than small text, which is highly periodic, and produces strong beats.

OK, Pan and Zoom with text on Kdenlive:-

It's an image, twice with pan and zoom and text, 1080p

The text is not being pan/zoomed though.

Ha, laugh, I never even noticed as I was watching the image move. Blind as a bat. I had another go with just the first clip though:-


Last one, promise. Text moves across, up and gets larger:-