image shifts depending on background

Jasonh wrote on 2/26/2007, 1:50 PM
I think this may be a problem that deals with the television or display device...so it may not be suited for this forum, but here it goes....

Basically I have an image in front of two separate backgrounds. The image is a transparent gif that is most suited for a white background.

Anyway, when the background behind the image transitions to the next background, the image shifts a little. It gets bigger. This is only a problem on the various television sets that I am using. I don't see, or I don't notice the problem on my LCD screen prior to rendering the DVD.

Comments

MPM wrote on 2/27/2007, 9:28 AM
Someone else will probably have a better answer, but my 1st suggestion would be to drop the gif in favor of png -- that way the background is irrelevant & you get full color spread. Not that that's your prob...

The only thing I've ever seen that sounds a *bit* similar is using interlaced rather than progressive video for DVDA menus & transitions.

If going progressive already &/or that doesn't help, what about rendering your background transition in Vegas?
TLF wrote on 2/27/2007, 12:14 PM
I take it you are using CRT (cathode ray tube) televisions, and that these are consumer devices.

You often find that CRTs suffer from transient line gain - the picture effectively stretched when scenes are bright. You can try adjusting the brightness and contrast to minimise these line gains, but then the image may not be very good.

Really there's not much you can do about it - it's a screen quality issue, not a DVD or DVDA issue.

Worley
jeremyk wrote on 2/27/2007, 12:15 PM
Sounds like a common problem with consumer CRT TVs called "bloom". If the image is bright, sending all those electrons to the phosphor screen drops the high voltage, and the deflection magnets steering the beam have a greater effect and the picture gets a little bigger.

Nothing you can really do about it except avoid abrupt changes from dark to light.

Jeremy

Edit: Dang, Worley, you beat me to it!
TLF wrote on 2/27/2007, 11:18 PM
@Jeremy,

I've never heard it called 'bloom' before, but that's much nicer than 'Transient Line Gains' (that specifically refers to horizontal stretching; I can't recall what the vertical equivalent is called).

My last CRT screen was dreadful - titles scrolling up the screen was enough to turn the picture to jelly. I was astounded when I bought an LCD television and verticals remained vertical and circles remained circles.

Rest assured that the problem is NOT with the picture on the DVD.

Worley