PAL image size

[mitchell65]

My experience is that it doesn't make any difference in resolution when e.g. zooming is applied.

It does on my HD TV

[erdna]

I retested on a fullHD TV, and indeed there is a difference. Edges are somewhat sharper, but there is a lot of aliasing, which make e.g. that a text on a banner in the image becomes almost unreadable when VS has to resize the large image. Apparently the oversized image is just being resampled without any Nyquist refiltering. I compaired a 3648x2736 image (straight on the timeline) with its resized (768x560) version on the same timeline. Made a 720x560 MPEG2 video file and played the file on my fullHD monitor through my PowerDVD8 SW player.

[Kenneth Veal]

jpeg ,RGB True colour, 24bit,Width 3071 Height 1838px,Res 28 px/cm,
size 16,537kb

[Trevor Andrew]

Hi Erdna

I compaired a 3648x2736 image (straight on the timeline) with its resized (768x560) version on the same timeline. .

With these images in the timeline, use pan and zoom on each, compare the difference in the timeline.

[erdna]

With pan and zoom it's even worse. an extra strong flicker on the characters becomes visible. Is there a way to post my .jpeg files (the original pic and the presized) so that other people can do a test?

[erdna]

I uploaded the 2 files in http://users.telenet.be/bettydemey/

[erdna]

I now added screenshots of the result ( not yet pan/zoomed) in an mpeg2 file played back with PDVD8.

[erdna]

Finally I found out that if you don't apply pan/scan on an oversized image it is being rendered without the right filtering, thereby causing aliasing. If pan/scan is being applied and the file rendered, the end result is indeed significantly better. (resolution). I now also uploaded the "problem" .mpg file where the pre-sized, and the oversized image clips were rendered without pan/scan applied. My conclusion is thus, to never use oversized image clips if there is no P/S involved.

[Trevor Andrew]

Hi erdna

Sorry for the delay in replying and thanks for the info and sample clips.
Interesting result.
In the past I have always used sizes to match the video frame, only recently increasing (double size) for my slide shows.
I don¡¦t use Pan & Zoom that much so will be taking a good look at the next slide show.

By the way I noticed you used interlaced video, have you try Frame Based for your slide shows.
I realise with video included we would use interlaced. Just a thought.